Genotypes and phenotypes in children with short stature: clinical indicators of SHOX haploinsufficiency

Clinical practice guidelines for the care of girls and women with Turner syndrome

Turner syndrome (TS) affects 50 per 100 000 females. TS affects multiple organs through all stages of life, necessitating multidisciplinary care. This guideline extends previous ones and includes important new advances, within diagnostics and genetics, estrogen treatment, fertility, co-morbidities, and neurocognition and neuropsychology. Exploratory meetings were held in 2021 in Europe and United States culminating with a consensus meeting in Aarhus, Denmark in June 2023. Prior to this, eight groups addressed important areas in TS care: (1) diagnosis and genetics, (2) growth, (3) puberty and estrogen treatment, (4) cardiovascular health, (5) transition, (6) fertility assessment, monitoring, and counselling, (7) health surveillance for comorbidities throughout the lifespan, and (8) neurocognition and its implications for mental health and well-being. Each group produced proposals for the present guidelines, which were meticulously discussed by the entire group. Four pertinent questions were submitted for formal GRADE (Grading of Recommendations, Assessment, Development and Evaluation) evaluation with systematic review of the literature. The guidelines project was initiated by the European Society for Endocrinology and the Pediatric Endocrine Society, in collaboration with members from the European Society for Pediatric Endocrinology, the European Society of Human Reproduction and Embryology, the European Reference Network on Rare Endocrine Conditions, the Society for Endocrinology, and the European Society of Cardiology, Japanese Society for Pediatric Endocrinology, Australia and New Zealand Society for Pediatric Endocrinology and Diabetes, Latin American Society for Pediatric Endocrinology, Arab Society for Pediatric Endocrinology and Diabetes, and the Asia Pacific Pediatric Endocrine Society. Advocacy groups appointed representatives for pre-meeting discussions and the consensus meeting.

Genotype and phenotype in patients with ACAN gene variants: Three cases and literature review

OBJECTIVE

To characterize the phenotype spectrum, diagnosis, and response to growth-promoting therapy in patients with ACAN variants causing familial short stature.

METHODS

Three families with ACAN variants causing short stature were reported. Similar cases in the literature were summarized, and the genotype and phenotype were analyzed.

RESULTS

Three novel heterozygous variants, c.757+1G>A, (splicing), c.6229delG, p.(Asp2078Tfs*1), and c.6679C>T, p.(Gln2227*) in the ACAN gene were identified. A total of 314 individuals with heterozygous variants from 105 families and 8 individuals with homozygous variants from 4 families were confirmed to have ACAN variants from literature and our 3 cases. Including our 3 cases, the variants reported comprised 33 frameshift, 39 missense, 23 nonsense, 5 splicing, 4 deletion, and 1 translocation variants. Variation points are scattered throughout the gene, while exons 12, 15, and 10 were most common (25/105, 11/105, and 10/105, respectively). Some identical variants existing in different families could be hot variants, c.532A>T, p.(Asn178Tyr), c.1411C>T, p.(Gln471*), c.1608C>A, p.(Tyr536*), c.2026+1G>A, (splicing), and c.7276G>T, p.(Glu2426*). Short stature, early-onset osteoarthritis, brachydactyly, midfacial hypoplasia, and early growth cessation were the common phenotypic features. The 48 children who received rhGH (and GnRHa) treatment had a significant height improvement compared with before (-2.18 ± 1.06 SD vs. -2.69 ± 0.95 SD, p < 0.001). The heights of children who received rhGH (and GnRHa) treatment were significantly improved compared with those of untreated adults (-2.20 ± 1.10 SD vs. -3.24 ± 1.14 SD, p < 0.001).

CONCLUSION

Our study achieves a new understanding of the phenotypic spectrum, diagnosis, and management of individuals with ACAN variants. No clear genotype-phenotype relationship of patients with ACAN variants was found. Gene sequencing is necessary to diagnose ACAN variants that cause short stature. In general, appropriate rhGH and/or GnRHa therapy can improve the adult height of affected pediatric patients caused by ACAN variants.

SHOX Variations in Idiopathic Short Stature in North India and a Review of Cases from Asian Countries

Objective

Short stature homeobox (SHOX) haploinsufficiency underlies idiopathic short stature (ISS) and Leri-Weill dyschondrosteosis. The worldwide prevalence of SHOX variations in ISS varies from 2.5% to 15.0%. The aim of this study was to assess the implication of SHOX variation in ISS in North Indians and compare this with other cases of SHOX variations from Asian population.

Methods

SHOX gene analysis was carried out by multiplex ligation-dependent probe amplification followed by Sanger sequencing in 54 patients with variable phenotypes. Comparison with other reports in a meta-analysis comprising the current study and 11 previous studies (n=979) was performed.

Results

SHOX analysis resulted in 12.9% positivity (7.4% deletions and 5.5% duplications). SHOX association was seen significantly related to gender, with predominance in females (p=0.047). Short arms and forearms were the only significantly associated trait seen in 51.9% of children. The overall prevalence of SHOX variation was 15.2% in Asians with ISS. No significant difference was found in geographical region-specific analysis.

Conclusion

This study summarises findings from the last decade and provides an updated picture of the prevalence of SHOX variations in Asians, emphasizing their potential as therapeutic targets in ISS patients. Further high quality, large investigations including functional validation is warranted to validate this association.

Growth Hormone Treatment to Final Height in Turner Syndrome: Systematic Review

PURPOSE

Turner syndrome (TS) is the most common sex chromosomal abnormality found in female subjects. It is a result of a partial or complete loss of one of the X chromosomes. Short stature is a hallmark of TS. Attainment of adult height (AH) within the normal range for height within the general female population represents the usual long-term goal of growth hormone (GH) treatment. The aim of this systematic review was to understand the efficacy of GH therapy on AH of patients with TS.

METHODS

The literature review yielded for analysis 9 articles published from 2010 to 2021. Using the data from this literature search, the goal was to answer 5 questions: (1) What is the efficacy of GH on AH of girls with TS?; (2) Is AH influenced by the age at initiation of GH treatment?; (3) What is the optimal dose of GH to improve AH?; (4) Can the timing of either spontaneous or induced puberty influence AH?; and (5) Can the karyotype influence AH in patients with TS?

FINDINGS

GH therapy and adequate dose could enable patients with TS to achieve appropriate AH compared with the possible final height without therapy. The greatest increase in height during GH therapy occurs in the prepubertal years, and if therapy is continued to AH, there is no further increase. Furthermore, karyotype did not show a predictive value on height prognosis and did not affect the outcome of GH administration or the height gain in girls with TS.

IMPLICATIONS

Even if GH therapy is safe, close monitoring is indicated and recommended. Further evidence is needed to understand what other parameters may influence AH in patients undergoing GH therapy.

Genetic analysis, ultrasound phenotype, and pregnancy outcomes of fetuses with Xp22.33 or Yp11.32 microdeletions

OBJECTIVES

The phenotypes of Xp22.33 or Yp11.32 microdeletions comprising the short-stature homeobox (SHOX) gene have been extensively described in adults and children. Herein, the prenatal ultrasound phenotype and pregnancy outcomes of fetuses with Xp22.33/Yp11.32 microdeletions were analyzed to improve our understanding, diagnosis, and monitoring of this genetic condition in the fetal stage.

METHODS

A total of 9,100 pregnant women referred to tertiary units for prenatal diagnosis were evaluated by chromosomal microarray analysis(CMA).

RESULTS

Seven (0.08 %) fetuses had Xp22.33/Yp11.32 microdeletions, ranging from 243 kb to 1.1 Mb, that comprised SHOX. The ultrasonic phenotypes differed among these fetuses, with three fetuses presenting abnormal bone development, one had labial-palatal deformity and strawberry head, two had an abnormal ultrasonic soft marker, and one had no abnormalities. After genetic counseling, only one couple underwent pedigree assessment, which confirmed the paternal origin of the microdeletion. This infant presented delayed speech development, whereas other three infants showed a typical postnatal development. In three cases, the parents chose to terminate the pregnancy.

CONCLUSIONS

The ultrasonic phenotype of fetuses with Xp22.33/Yp11.32 microdeletions resulting in SHOX heterozygosity loss is variable. Prenatal CMA can quickly and effectively diagnose Xp22.33/Yp11.32 microdeletions and SHOX loss, which may help prenatal counseling.

Identification of a second genetic alteration in patients with SHOX deficiency individuals: a potential explanation for phenotype variability

OBJECTIVE

Our study aimed to assess the impact of genetic modifiers on the significant variation in phenotype that is observed in individuals with SHOX deficiency, which is the most prevalent monogenic cause of short stature.

DESIGN AND METHODS

We performed a genetic analysis in 98 individuals from 48 families with SHOX deficiency with a target panel designed to capture the entire SHOX genomic region and 114 other genes that modulate growth and/or SHOX action. We prioritized rare potentially deleterious variants.

RESULTS

We did not identify potential deleterious variants in the promoter or intronic regions of the SHOX genomic locus. In contrast, we found eight heterozygous variants in 11 individuals from nine families in genes with a potential role as genetic modifiers. In addition to a previously described likely pathogenic (LP) variant in CYP26C1 observed in two families, we identified LP variants in PTHLH and ACAN, and variants of uncertain significance in NPR2, RUNX2, and TP53 in more affected individuals from families with SHOX deficiency. Families with a SHOX alteration restricted to the regulatory region had a higher prevalence of a second likely pathogenic variant (27%) than families with an alteration compromising the SHOX coding region (2.9%, P = .04).

CONCLUSION

In conclusion, variants in genes related to the growth plate have a potential role as genetic modifiers of the phenotype in individuals with SHOX deficiency. In individuals with SHOX alterations restricted to the regulatory region, a second alteration could be critical to determine the penetrance and expression of the phenotype.

Shortened fetal long bones: A notable intrauterine phenotypic feature in SHOX-associated skeletal dysplasia

OBJECTIVE

To explore the intrauterine phenotypic spectrum of short stature homeobox-containing (SHOX) gene-associated skeletal dysplasia and provide genetic counseling at-risk pregnancies.

METHOD

We analyzed the fetuses with SHOX-microdeletions identified by single nucleotide polymorphism (SNP)-array. The intrauterine phenotypes and outcomes were further elaborated.

RESULTS

Nine fetuses carrying a single SHOX-microdeletion were reported, with deletion sizes ranging from 0.134 to 1.35 Mb. Shortened long bones were observed in all fetuses, varying from -2.0 standard deviation (SD) to -5.3 SD. Moreover, all cases had a femur length/foot ratio less than 0.87 and a femur/abdominal circumference ratio greater than 0.16, suggesting that non-lethal skeletal dysplasia may be involved. Two fetuses showed intrauterine growth restriction, and two had nasal bone hypoplasia. Prenatal ultrasonography did not reveal other obvious anomalies, including the Madelung deformity. Five microdeletions were inherited and one was de novo. Five terminations and four newborns were recorded. Two newborns had normal stature, and two were short-statured (height <3rd percentile), with one having inflexible wrists.

CONCLUSIONS

SHOX haploinsufficiency may manifest with shortened fetal long bones. The combination of history taking, prenatal ultrasonography, and SNP-array can prompt early prenatal diagnosis and timely postnatal treatment of SHOX-associated skeletal dysplasia.

Body proportions in patients with Turner syndrome on growth hormone treatment

BACKGROUND

: In this cross-sectional study, we aimed to evaluate auxological measurements and detailed body proportions of recombinant human growth hormone (GH)-treated patients with Turner syndrome (TS) and compare them with a group of healthy females.

METHODS

We evaluated 42 patients with TS who received GH treatment and 20 healthy controls. Anthropometric measurements were taken and target height, body mass index (BMI), arm span-height difference, extremity-to-trunk ratio, and Manouvrier's skelic index were calculated.

RESULTS

: The median (min-max) age of the patients at the time of evaluation was 13.6 (4.3-20.7) years, and the control group was 12.9 (3.8-23.7) years. Height, sitting height, and arm span of TS patients were significantly lower than those of the control group. Sitting height/height ratio (SHR) was in normal ranges in both groups and BMI was significantly higher in TS patients when compared to the control group. According to Manouvrier's skelic index, TS patients had shorter legs than the control group (p = 0.001). The extremity-trunk ratio was significantly decreased in TS patients compared to healthy controls (p < 0.001). There was no significant difference between the karyotype groups in terms of these indexes.

DISCUSSION

TS patients had short stature, increased BMI and waist circumference, normal head circumference, and decreased extremity-trunk ratio. Sitting height and leg length were short; however, the SHR standard deviation score (SDS) was in the normal range. Despite being treated with GH, TS patients had disproportionate short stature. The disproportion in TS patients was similar to short-stature homeobox-containing gene (SHOX) deficiency, which is considered to be SHOX haploinsufficiency in the etiopathogenesis of short stature.

SHOX Whole Gene Duplications Are Overrepresented in SHOX Haploinsufficiency Phenotype Cohorts

Transcription of SHOX is dependent upon the interaction of the gene with a complex array of flanking regulatory elements. Duplications that contain flanking regulatory elements but not the SHOX gene have been reported in individuals with SHOX haploinsufficiency syndromes, suggesting that alterations to the physical organisation or genomic architecture may affect SHOX transcription. Individuals with tall stature and an additional X or Y chromosome have an extra copy of both the SHOX gene and the entire SHOX regulatory region, so all three copies of SHOX can be expressed fully. However, for a duplication of the SHOX gene that does not include all of the flanking regulatory elements, the potential effect on SHOX expression is difficult to predict. We present nine unpublished individuals with a SHOX whole gene duplication in whom the duplication contains variable amounts of the SHOX regulatory region, and we review 29 similar cases from the literature where phenotypic data were clearly stated. While tall stature was present in a proportion of these cases, we present evidence that SHOX whole gene duplications can also result in a phenotype more typically associated with SHOX haploinsufficiency and are significantly overrepresented in Leri-Weill dyschondrosteosis and idiopathic short stature probands compared to population controls. Although similar-looking duplications do not always produce a consistent phenotype, there may be potential genotype-phenotype correlations regarding the duplication size, regulatory element content, and the breakpoint proximity to the SHOX gene. Although ClinGen does not currently consider SHOX whole gene duplications to be clinically significant, the ClinGen triplosensitivity score does not take into account the context of the duplication, and more is now known about SHOX duplications and the role of flanking elements in SHOX regulation. The evidence presented here suggests that these duplications should not be discounted without considering the extent of the duplication and the patient phenotype, and should be included in diagnostic laboratory reports as variants of uncertain significance. Given the uncertain pathogenicity of these duplications, any reports should encourage the exclusion of all other causes of short stature where possible.

Genetic Analysis and Sonography Characteristics in Fetus with SHOX Haploinsufficiency

OBJECTIVE

SHOX haploinsufficiency have been commonly found in isolated short stature (ISS) and Léri-Weill dyschondrosteosis (LWD) patients. However, few publications have described the genetic analysis and clinical characteristics of fetuses with SHOX haploinsufficiency.

METHODS

Chromosomal microarray (CMA) were applied in 14,051 fetuses and sequentially whole exome sequence (WES) in 1340 fetuses who underwent prenatal diagnosis during 2016-2021. The analysis and summary of molecular genetics, sonographic characteristics, and follow-up results were performed in fetuses with SHOX haploinsufficiency without other genetic etiologies. A comparison was made between three groups according to prenatal diagnostic indications.

RESULTS

8 (0.06%) fetuses of SHOX haploinsufficiency were all detected by CMA, of which 5 (62.5%) were detected with short long bones by ultrasound scan, and 4 were inherited from their previously undiagnosed parents. No pathogenic SHOX variants were found by WES. The detection rate of SHOX haploinsufficiency was obviously higher in the short long bone group (2.6%, 5/191) than the other abnormality group (0.03%, 1/3919) or no ultrasound abnormality group (0.02%, 2/9941). Three of the fetuses were liveborn with normal growth up to the age of four and four were terminated.

CONCLUSION

The phenotype of fetuses with SHOX haploinsufficiency is highly varied. Over 1/3 of the cases exhibited no phenotype and nearly 2/3 with short long bones, in the absence of Madelung deformity during fetal development. SHOX haploinsufficiency should be considered in all antenatal presentations, especially in the case of isolated short long bones. CMA can provide effective detection.

RARE DOSAGE ABNORMALITIES - COPY NUMBER VARIATIONS FLANKING THE SHOX GENE

Background

Molecular defects in the SHOX gene including deletions, duplications or pathogenic point mutations are responsible for well-known pathologies involving short stature as a clinical manifestation: Léri-Weill dyschondrosteosis, Langer mesomelic dysplasia, Turner syndrome or idiopathic short stature. Duplications flanking the SHOX gene (upstream or downstream of the intact SHOX gene involving conserved non-coding cis-regulatory DNA elements - CNEs) have been described but their clinical involvement is still difficult to understand.

Results

We describe two cases with short stature and normal GH-IGF1 status. Multiplex ligation-dependent probe amplification (MLPA) and array comparative genomic hybridization (arrayCGH) identified in both cases heterozygous duplications involving downstream regions of SHOX gene, within CNEs (CNE8, CNE9 and CNE4, CNE5, CNE6, ECR1, CNE8, CNE9 and surrounding areas, respectively). One of the cases showed a maternally inherited duplication. Although every case has several particularities, we consider that duplications in these non-coding regions of SHOX gene may explain the short stature phenotype.

Conclusion

To our knowledge, these are the first Romanian-reported cases of ISS with a large duplication of downstream SHOX enhancers CNEs region. The spectrum of phenotypic consequences and the exact mechanism of the presumed clinical expression of these genetic alterations still needs to be evaluated and described.

SHOX Deletion and Idiopathic Short Stature: What Does the Clinician Need to Know? Case Series Report

Children diagnosticated with idiopathic short stature (ISS) are probably, in most cases, underdiagnosticated. The genetic causes of ISS may be mutations of genes involved in local regulation of the growth plate or genes involved in the GH-IGF1 axis physiology. We present a kindred of five children evaluated for short stature or low normal stature, initially diagnosticated as idiopathic short stature, familial short stature, or being small for gestational age. Clinical signs suggestive of SHOX deletion screening in a child with short stature are low arm span/height ratio, increased sitting height/height ratio, BMI > 50% percentile, Madelung deformity, cubitus valgus, bowing and shortening of the forearm, dislocation of the ulna (at the elbow), and the appearance of muscular hypertrophy. Radiological characteristics suggestive of SHOX deficiency are triangularisation of the distal radial epiphysis, an enlarged diaphysis of the radius plus bowing of the radius, the convexity of the distal radial metaphysis, short fourth and fifth metacarpals, pyramidalization of the carpal row. Treatment with rGH is approved for children with SHOX gene deficiency and short stature. This kindred is an example that familial short stature, idiopathic short stature, and short stature due to a small gestational age are not final diagnoses. Complex investigations are necessary to identify the precise cause, leading to optimal clinical management. Treatment with rGH is an option for some of them; for others, it has no therapeutic response and, in some cases, is even harmful.

Clinical Indications for Growth Hormone Therapy

Growth hormone (GH) is an injectable medication originally used to replace the deficiency of the hormone, but has expanded to treating conditions that may reduce growth and adult height even when the body maintains endogenous GH production. In the United States, there are 8 Food and Drug Administration (FDA)-approved indications for pediatric GH therapy: GH deficiency, Prader-Willi Syndrome, small for gestational age (SGA) without catch-up growth, idiopathic short stature, Turner syndrome, SHOX gene haploinsufficiency, Noonan Syndrome, and chronic renal insufficiency. We characterize the growth patterns and effects of GH treatment in each of these indications. We also review patterns of growth that warrant referral to a pediatric endocrinologist, as well as safety updates. This review is intended to guide practitioners on the initial evaluation and management of patients with short stature, and the indications for GH therapy.

Novel insights in Turner syndrome

PURPOSE OF REVIEW

Turner syndrome is the most common sex chromosome abnormality in female individuals, affecting 1/2000-1/2500 female newborns. Despite the high incidence of this condition, the mechanisms underlying the development of multiorgan dysfunction have not been elucidated.

RECENT FINDINGS

Clinical features involve multiple organ systems and include short stature, dysmorphic facial features, delayed puberty and gonadal failure, cardiac and renal abnormalities, audiologic abnormalities, and a high prevalence of endocrine and autoimmune disorders. Paucity of available genotype/phenotype correlation limits the ability of clinicians to provide accurate guidance and management. Given the advent of robust genetic testing and analysis platforms, developments in the genetic basis of disease are materializing at a rapid pace.

SUMMARY

The objective of this review is to highlight the recent advances in knowledge and to provide a framework with which to apply new data to the foundational understanding of the condition.

Pathogenic Copy Number and Sequence Variants in Children Born SGA With Short Stature Without Imprinting Disorders

CONTEXT

Children born small-for-gestational-age with short stature (SGA-SS) is associated with (epi)genetic defects, including imprinting disorders (IDs), pathogenic copy number variants (PCNVs), and pathogenic variants of genes involved in growth. However, comprehensive studies evaluating these 3 factors are very limited.

OBJECTIVE

To clarify the contribution of PCNVs and candidate pathogenic variants to SGA-SS.

DESIGN

Comprehensive molecular analyses consisting of methylation analysis, copy number analysis, and multigene sequencing.

METHODS

We enrolled 140 patients referred to us for genetic testing for SGA-SS. Among them, we excluded 42 patients meeting Netchine-Harbison clinical scoring system criteria for Silver-Russell syndrome and 4 patients with abnormal methylation levels of the IDs-related differentially methylated regions. Consequently, we conducted copy number analysis and multigene sequencing for 86 SGA-SS patients with sufficient sample volume. We also evaluated clinical phenotypes of patients with PCNVs or candidate pathogenic variants.

RESULTS

We identified 8 (9.3%) and 11 (12.8%) patients with PCNVs and candidate pathogenic variants, respectively. According to the American College of Medical Genetics standards and guidelines, 5 variants were classified as pathogenic and the remaining 6 variants were classified as variants of unknown significance. Genetic diagnosis was made in 12 patients. All patients with PCNVs or candidate pathogenic variants did not correspond perfectly to characteristic clinical features of each specific genetic cause.

CONCLUSION

We clarified the contribution of PCNVs and pathogenic variants to SGA-SS without IDs. Comprehensive molecular analyses, including copy number analysis and multigene sequencing, should be considered for patients with unknown SGA-SS etiology.

Adams-Oliver Syndrome: Vestigial Tail and Genetics Update

Adams-Oliver syndrome is a well-recognized autosomal dominant disorder for which mutations in six genes are etiologic, but account for only one-third of the cases. We report a patient with two genetic disorders; Adams-Oliver and Xp22.33 deletion syndromes, as well as a vestigial pseudotail. The presence of a pseudotail has not previously been reported in either of these genetic conditions. Absence of a molecular etiology underlying Adams-Oliver syndrome confirms that there are additional genetic causes to be identified.

Clinical impact of variants in non-coding regions of SHOX - Current knowledge

The short stature homeobox-containing (SHOX) is the most frequently analysed gene in patients classified as short stature patients (ISS) or diagnosed with Leri-Weill dyschondrosteosis (LWD), Langer mesomelic dysplasia (LMD), or Madelung deformity (MD). However, clinical testing of this gene focuses primarily on single nucleotide variants (SNV) in its coding sequences and copy number variants (CNV) overlapping SHOX gene. This review summarizes the clinical impact of variants in noncoding regions of SHOX. RECENT FINDINGS: CNV extending exclusively into the regulatory elements (i.e., not interrupting the coding sequence) are found more frequently in downstream regulatory elements of SHOX. Further, duplications are more frequent than deletions. Interestingly, downstream duplications are more common than deletions in patients with ISS or LWD but no such differences exist for upstream CNV. Moreover, the presence of specific CNVs in the patient population suggests the involvement of additional unknown factors. Some of its intronic variants, notably NM_000451.3(SHOX):c.-9delG and c.-65C>A in the 5'UTR, have unclear clinical roles. However, these intronic SNV may increase the probability that other CNV will arise de novo in the SHOX gene based on homologous recombination or incorrect splicing of mRNA. SUMMARY: This review highlights the clinical impact of noncoding changes in the SHOX gene and the need to apply new technologies and genotype-phenotype correlation in their analysis.

Pediatric growth hormone treatment in Italy: A systematic review of epidemiology, quality of life, treatment adherence, and economic impact

Objectives

This systematic review aims to describe 1) the epidemiology of the diseases indicated for treatment with growth hormone (GH) in Italy; 2) the adherence to the GH treatment in Italy and factors associated with non-adherence; 3) the economic impact of GH treatment in Italy; 4) the quality of life of patients treated with GH and their caregivers in Italy.

Methods

Systematic literature searches were performed in PubMed, Embase and Web of Science from January 2010 to March 2021. Literature selection process, data extraction and quality assessment were performed by two independent reviewers. Study protocol has been registered in PROSPERO (CRD42021240455).

Results

We included 25 studies in the qualitative synthesis. The estimated prevalence of growth hormone deficiency (GHD) was 1/4,000–10,000 in the general population of children; the prevalence of Short Stature HOmeoboX Containing gene deficiency (SHOX-D) was 1/1,000–2,000 in the general population of children; the birth prevalence of Turner syndrome was 1/2,500; the birth prevalence of Prader-Willi syndrome (PWS) was 1/15,000. Treatment adherence was suboptimal, with a range of non-adherent patients of 10–30%. The main reasons for suboptimal adherence were forgetfulness, being away from home, pain/discomfort caused by the injection. Economic studies reported a total cost for a complete multi-year course of GH treatment of almost 100,000 euros. A study showed that drug wastage can amount up to 15% of consumption, and that in some Italian regions there could be a considerable over- or under-prescribing. In general, patients and caregivers considered the GH treatment acceptable. There was a general satisfaction among patients with regard to social and school life and GH treatment outcomes, while there was a certain level of intolerance to GH treatment among adolescents. Studies on PWS patients and their caregivers showed a lower quality of life compared to the general population, and that social stigma persists.

Conclusion

Growth failure conditions with approved GH treatment in Italy constitute a significant burden of disease in clinical, social, and economic terms. GH treatment is generally considered acceptable by patients and caregivers. The total cost of the GH treatment is considerable; there are margins for improving efficiency, by increasing adherence, reducing drug wastage and promoting prescriptive appropriateness.

Novel Insights Into the Genetic Causes of Short Stature in Children

Short stature is a common reason for consulting a growth specialist during childhood. Normal height is a polygenic trait involving a complex interaction between hormonal, nutritional and psychosocial components. Genetic factors are becoming very important in the understanding of short stature. After exclusion of the most frequent causes of growth failure, clinicians need to evaluate whether a genetic cause might be taken into consideration. In fact, genetic causes of short stature are probably misdiagnosed during clinical practice and the underlying cause of short stature frequently remains unknown, thus classifying children as having idiopathic short stature (ISS). However, over the past decade, novel genetic techniques have led to the discovery of novel genes associated with linear growth and thus to the ability to define new possible aetiologies of short stature. In fact, thanks to the newer genetic advances, it is possible to properly re-classify about 25–40% of children previously diagnosed with ISS. The purpose of this article is to describe the main monogenic causes of short stature, which, thanks to advances in molecular genetics, are assuming an increasingly important role in the clinical approach to short children.

Prevention of Growth Failure in Turner Syndrome: Long-Term Results of Early Growth Hormone Treatment in the "Toddler Turner" Cohort

INTRODUCTION

In the randomized "Toddler Turner" study, girls who received growth hormone (GH) starting at ages 9 months to 4 years (early-treated [ET] group) had marked catch-up growth and were 1.6 ± 0.6 SD taller than untreated (early-untreated [EUT]) control girls after 2 years. However, whether the early catch-up growth would result in greater near-adult height (NAH) was unknown. Therefore, this extension study examined the long-term effects of toddler-age GH treatment on height, pubertal development, and safety parameters.

METHODS

Toddler Turner study participants were invited to enroll in a 10-year observational extension study for annual assessments of growth, pubertal status, and safety during long-term GH treatment to NAH for both ET and EUT groups.

RESULTS

The ET group was taller than the EUT group at all time points from preschool to maturity and was significantly taller at the onset of puberty (p = 0.016), however, the difference was not significant at NAH. For the full cohort (ET + EUT combined, n = 50) mean (± SD) NAH was 151.2 ± 7.1 cm at age 15.0 ± 1.3 years. NAH standard deviation score (SDS) was within the normal range (>-2.0) for 76% of ET and 60% of EUT subjects (68% overall) and correlated strongly with height SDS at GH start (r = 0.78; p < 0.01), which in turn had a modest inverse correlation with age at GH start (i.e., height SDS declined with increasing age in untreated girls [r = -0.30; p = 0.016]). No new safety concerns arose.

CONCLUSION

Although the ET group was taller throughout, height SDS at NAH was not significantly different between groups due to catch-down growth of ET girls during lapses in GH treatment after the Toddler study and similar long-term GH exposure overall. Early initiation of GH by age 6 years, followed by uninterrupted treatment during childhood, can prevent ongoing growth failure and enable attainment of height within the normal range during childhood, adolescence, and adulthood.

Rare dosage abnormalities flanking the SHOX gene

Background

Transcriptional regulation of the SHOX gene is highly complex. Much of our understanding has come from the study of copy number changes of conserved non-coding sequences both upstream and downstream of the gene. Downstream deletions have been frequently reported in patients with Leri–Weill dyschondrosteosis or idiopathic short stature. In contrast, there are only four cases in the literature of upstream deletions that remove regulatory elements. Although duplications flanking the SHOX gene have also been reported, their pathogenicity is more difficult to establish. To further evaluate the role of flanking copy number variants in SHOX-related disorders, we describe nine additional patients from a large SHOX diagnostic cohort.

Results

The nine cases presented here include five with duplications (two upstream of SHOX and three downstream), one with a downstream triplication and three with upstream deletions. Two of the deletions remove a single conserved non-coding element (CNE-3) while the third does not remove any known regulatory element but is just 4 kb upstream of SHOX, and the deleted region may be important in limb bud development. We also describe six families with novel sequence gains flanking SHOX. Three families had increased dosage of a proposed regulatory element approximately 380 kb downstream of SHOX (X:970,000), including one family with the first ever reported triplication of this region. One family had two in cis downstream duplications co-segregating with LWD, and the two others had a duplication of just the upstream SHOX regulatory element CNE-5.

Conclusions

This study further extends our knowledge of the range of variants that may potentially cause SHOX-related phenotypes and may aid in determining the clinical significance of similar variants.

Copy number variations residing outside the SHOX enhancer region are involved in Short Stature and Léri-Weill dyschondrosteosis

Background

SHOX enhancer CNVs, affecting one or more of the seven recognized evolutionary conserved non‐coding elements (CNEs) represent one of the most frequent cause of SHOX‐haploinsufficiency. During the diagnostic workflow deletions/duplications have been identified downstream SHOX not including any of the these CNEs.

Methods

Fine tiling aCGH and breakpoint PCR were used to characterize the critical interval and to search for novel alterations in a cohort of selected patients.

Results

Screening of 252 controls provided evidence that duplications in this area represent likely benign variants whereas none of the deletions were detected. These findings suggested that other alterations relevant for SHOX‐haploinsufficiency might be missed by the standard diagnostic methods. To identify such undisclosed elements, the aCGH was used to reanalyze 52 unresolved cases with clinical features strongly suggestive of SHOX‐haploinsufficiency. This analysis followed by the screening of 210 patients detected two partially overlapping small deletions of ~12 and ~8 kb in four unrelated individuals, approximately 15 kb downstream SHOX, that were absent in 720 normal stature individuals.

Conclusion

Our results strengthen the hypothesis that alterations of yet unidentified cis‐regulatory elements residing outside those investigated through conventional methods, might explain the phenotype in ISS/LWD patients thus enlarging the spectrum of variants contributing to SHOX‐haploinsufficiency.

Turner syndrome with Xp deletions and rare endometrial abnormalities: A case report

RATIONALE

Turner syndrome (TS) is a genetic disorder associated with abnormalities of the X chromosome related to ovarian function, but whether it is associated with endometrial abnormalities is still not clear.

PATIENT CONCERNS

We report the case of a 26-year-old Han Chinese woman with TS and Xp11.2 deletion, presenting with short final stature, ovarian hypofunction, unexplained cystic dilatation of the entire endometrium, and endometrial thickening.

DIAGNOSES

The patient was diagnosed with chromosome Xp11.2 deletion through cytogenetic analysis and ultrasonic and endometrial pathology.

INTERVENTIONS

The patient was treated with conventional in vitro fertilization preimplantation genetic testing for 1 cycle.

OUTCOMES

Cytogenetic examination showed karyotype 45, X, del (X) del (p11, 2). Ultrasonic examination showed uneven endometrium thickness and a full-stage cystic dilation echo. After 1 cycle of in vitro fertilization treatment, 4 eggs were obtained without forming an available embryo.

LESSONS

To our knowledge, the present case is the first report of a patient with TS with Xp deletions and ultrasound imaging endometrial abnormalities. Our findings expand the phenotypic spectrum of TS and may provide a reference for other clinicians.

Clinical and cytogenetic characteristics of patients diagnosed with Turner syndrome in a clinical genetics service: cross-sectional retrospective study

BACKGROUND

Turner syndrome (TS) is a rare genetic disease. Understanding its clinical findings contributes to better management of clinical conditions.

OBJECTIVE

To investigate the clinical and karyotypic characteristics of patients diagnosed with TS at two reference services for clinical genetics in southern Brazil.

DESIGN AND SETTING

Retrospective cross-sectional study conducted in two clinical genetics services in Porto Alegre (RS), Brazil.

METHODS

The sample consisted of 59 patients with TS diagnosed from 1993 to 2019. A review of their medical records was performed and a standard protocol was filled out.

RESULTS

The average age of the patients at diagnosis was 15.9 years, and 40.7% were over 13 years old. The largest proportion of them (42.4%) had been referred from an endocrinology department and their constitution was 45,X (40.7%). The most common clinical findings were short stature (85.7%), hypoplastic/ hyperconvex nails (61.2%), low posterior hairline (52.1%) and cubitus valgus (45.8%). There was no difference regarding the presence of short stature (P = 0.5943), number of dysmorphia (P = 0.143), anatomical regions affected and malformations identified through imaging examinations (P = 1.0000), regarding the presence or absence of 45,X constitution. Only 6% of the patients had used growth hormone and 43%, estrogen.

CONCLUSION

We found that, in general, patients with TS were being diagnosed late. This has important implications for their treatment. In addition, only a small proportion of the patients were undergoing further examination or evaluation, which appeared to be leading to underdiagnosis of many abnormalities.

Arm Span and Its Relation to Height in a 2- to 17-Year-Old Reference Population and Heterozygous Carriers of ACAN Variants

BACKGROUND/OBJECTIVES

In the clinical assessment of a short or tall child, estimating body disproportion is useful to assess the likelihood of a primary growth disorder, e.g., skeletal dysplasia. Our objectives were (1) to use data from the Maastricht study on healthy children (2-17 years) to calculate relative arm span (AS) for height (H) to serve as age references for clinical purposes; (2) to assess its age and sex dependency; and (3) to investigate relative AS adjustment for age and sex in individuals with ACAN haploinsufficiency.

METHODS

The Maastricht study data (2,595 Caucasian children, 52% boys, 48% girls) were re-analysed to produce reference tables and graphs for age and sex of AS - H and AS/H. Published information on AS/H in Europeans was used as reference data for adults. Relative AS from 33 patients with ACAN haploinsufficiency were plotted against reference data and expressed as standard deviation score (SDS) for age and sex.

RESULTS

Mean AS - H from 2 to 17 years increased from -1.2 to +1.5 cm in boys and from -4.8 to +1.6 cm in girls. Mean AS/H increased from 0.9848 to 1.0155 in boys and from 0.9468 to 1.0028 in girls. Mean AS/H in patients with ACAN haploinsufficiency was approximately 1.0, 1.5 and 0.5 SDS in young children, adolescents and 20- to 50-year-olds, respectively, and normal thereafter.

CONCLUSIONS

These reference charts can be used for 2- to 17-year-old children/adolescents. Carriers of ACAN haploinsufficiency have an elevated mean AS/H in childhood and adolescence and a slightly elevated ratio till 50 years.

A Polygenic Risk Score to Predict Future Adult Short Stature Among Children

CONTEXT

Adult height is highly heritable, yet no genetic predictor has demonstrated clinical utility compared to mid-parental height.

OBJECTIVE

To develop a polygenic risk score for adult height and evaluate its clinical utility.

DESIGN

A polygenic risk score was constructed based on meta-analysis of genomewide association studies and evaluated on the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort.

SUBJECTS

Participants included 442 599 genotyped White British individuals in the UK Biobank and 941 genotyped child-parent trios of European ancestry in the ALSPAC cohort.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Standing height was measured using stadiometer; Standing height 2 SDs below the sex-specific population average was considered as short stature.

RESULTS

Combined with sex, a polygenic risk score captured 71.1% of the total variance in adult height in the UK Biobank. In the ALSPAC cohort, the polygenic risk score was able to identify children who developed adulthood short stature with an area under the receiver operating characteristic curve (AUROC) of 0.84, which is close to that of mid-parental height. Combining this polygenic risk score with mid-parental height or only one of the child's parent's height could improve the AUROC to at most 0.90. The polygenic risk score could also substitute mid-parental height in age-specific Khamis-Roche height predictors and achieve an equally strong discriminative power in identifying children with a short stature in adulthood.

CONCLUSIONS

A polygenic risk score could be considered as an alternative or adjunct to mid-parental height to improve screening for children at risk of developing short stature in adulthood in European ancestry populations.

Pubertal boy presenting with mild disproportionate short stature

A boy aged 12 years was referred with short stature. He was born at term, of adequate weight (10-25th centile) and length (10-25th centile), which settled to just below the third centile from 18 months of age, with a growth deceleration in the last 6 months (growth velocity -2.1 standard deviation score, according to Tanner charts). He was otherwise asymptomatic. His mother's height was 155 cm, and father's height 158 cm, and he was growing near his target height centile (-2.26 SDS, <3rd centile).On examination, his height was -2.22 SDS, with normal weight and body mass index (BMI). Pubertal stage corresponded to Tanner 2, with a testicular volume of 4 mL. His legs and forearms appeared shorter, with arm span/height ratio 0.93 (normal value >0.965) and sitting height/height ratio 0.56 (slightly above the normal upper value of 0.55). He resembled his father, whose wrists were abnormally curved (figure 1). The patient's hand X-ray showed that bone age was similar to chronological age.

Coexistence of dyschondrosteosis associated to SHOX deficiency, pseudohypoparathyroidism 1B, and chronic autoimmune thyroiditis: a case report

We present an unusual case of SHOX deficiency associated with Léri-Weill dyschondrosteosis (LWD), Hashimoto's thyroiditis and pseudohypoparathyroidism 1B in a young woman. To our knowledge, this is the first ever report of these disorders coexisting. At the age of nine years, the proband was diagnosed of hypothyroidism due to Hashimoto's thyroiditis, and developed biochemical abnormalities consistent with hyperphosphatemia, mild hypocalcemia and elevated parathyroid hormone without any clinical symptoms except short stature. Replacement therapy with levothyroxine, calcium and alphacalcidol was initiated. The diagnosis of pseudohypoparathyroidism 1B was confirmed at the age of 17.5 years with the demonstration of methylation alteration at the GNAS locus. At the age of 16 years, 3.5 years after her menarche, she presented clear features of LWD. A large deletion of the SHOX gene was confirmed. Family genetic tests were not doable since she was adopted. We discuss the diagnostic challenges of these coexisting rare endocrinopathies.

Diagnostic evaluation of central precocious puberty in girls

BACKGROUND

The gonadotropin-releasing hormone (GnRH) stimulation test is the gold standard for confirming the activation of the hypothalamic-pituitary-gonadal axis in central precocious puberty (CPP). However, it is time-consuming and costly. Our aim was to search for a simpler diagnostic modality for CPP by 1) evaluating the performance of basal serum luteinizing hormone (LH), 2) constructing a practical scoring system, and 3) determining the optimal single sampling time for serum LH in the GnRH stimulation test.

METHODS

Data of girls aged between 3 and 9 years at the time of the GnRH stimulation test, who attended our endocrine clinic at the MacKay Children's Hospital for signs of puberty between July 2014 and June 2019, were analyzed retrospectively. We recorded patients' age, height, weight, breast Tanner stage (BS), bone age, serum LH, and follicle-stimulating hormone (FSH). Receiver operating characteristic (ROC) curves and the Youden index were used to obtain the optimal basal serum LH level. Binary logistic regression was employed to construct a practical scoring system. Cross-sectional, cumulative frequency, and ROC curves were used to simplify the GnRH stimulation test.

RESULTS

Overall, 381 sets of GnRH stimulation tests were performed in 313 patients. Basal serum LH ≥ 0.2 IU/L demonstrated 70% sensitivity and 70% specificity for predicting positive GnRH stimulation test results. The practical scoring system (3 × BS + 3 × LH + 4 × FSH) showed 76% sensitivity and 72% specificity. The serum LH level at 30 min after intravenous gonadorelin exhibited 99% sensitivity and 100% specificity.

CONCLUSION

Single sampling of serum LH at 30th minute post-injection of GnRH demonstrated a diagnostic performance equivalent to the traditional GnRH stimulation test in diagnosing CPP. Therefore, this approach could become the simplest diagnostic modality.

Detection of SHOX Gene Variations in Patients with Skeletal Abnormalities with or without Short Stature

OBJECTIVE

SHOX gene mutations constitute one of the genetic causes of short stature. The clinical phenotype includes variable degrees of growth impairment, such as Langer mesomelic dysplasia (LMD), Léri-Weill dyschondrosteosis (LWD) or idiopathic short stature (ISS). The aim of this study was to describe the clinical features and molecular results of SHOX deficiency in a group of Turkish patients who had skeletal findings with and without short stature.

METHODS

Forty-six patients with ISS, disproportionate short stature or skeletal findings without short stature from 35 different families were included. SHOX gene analysis was performed using Sanger sequencing and multiplex ligation-dependent probe amplification analysis.

RESULTS

Three different point mutations (two nonsense, one frameshift) and one whole SHOX gene deletion were detected in 15 patients from four different families. While 4/15 patients had LMD, the remaining patients had clinical features compatible with LWD. Madelung’s deformity, cubitus valgus, muscular hypertrophy and short forearm were the most common phenotypic features, as well as short stature. Additionally, hearing loss was detected in two patients with LMD.

CONCLUSION

This study has presented the clinical spectrum and molecular findings of 15 patients with SHOX gene mutations or deletions. SHOX deficiency should be especially considered in patients who have disproportionate short stature or forearm anomalies with or without short stature. Although most of the patients had partial or whole gene deletions, SHOX gene sequencing should be performed in suspected cases. Furthermore, conductive hearing loss may rarely accompany these clinical manifestations.

Short stature and SHOX (Short stature homeobox) variants-efficacy of screening using various strategies

Background

SHOX mutations have previously been described as causes of Léri-Weill dyschondrosteosis (LWD), Langer mesomelic dysplasia (LMD), and idiopathic short stature. The loss of X chromosome—Turner syndrome or mosaic 45,X/46,XX or 46,XY—also leads to the heterozygous loss of SHOX in patients with short stature only or with features similar to LWD. The aim of this study was to assess the efficacy of the targeted screening for SHOX variants, which involved different methods in the laboratory analysis of short stature. We determined the significance and positive predictive value of short stature for the detection of SHOX variants.

Methods

Targeted screening for variants in SHOX involving MLPA, sequencing, karyotyping and FISH was performed in the short stature cohort (N = 174) and control cohort (N = 91). The significance of short stature and particular characteristics for the detection of SHOX variants was determined by Fisher’s exact test, and the probability of SHOX mutation occurrence was calculated using a forward/stepwise logistic regression model.

Results

In total, 27 and 15 variants influencing SHOX were detected in the short stature and control cohorts, respectively (p > 0.01). Sex chromosome aberrations and pathogenic CNV resulting in diagnosis were detected in eight (4.6%) and five (2.9%) patients of the short stature group and three (3.3%) and one (1.1%) individuals of the control group. VUS variants were discovered in 14 (8.0%) and 11 (12.1%) individuals of the short stature and control groups, respectively. MLPA demonstrated the detection rate of 13.22%, and it can be used as a frontline method for detection of aberrations involving SHOX. However, only mosaicism of monosomy X with a higher frequency of monosomic cells could be reliably discovered by this method. Karyotyping and FISH can compensate for this limitation; their detection rates in short stature group were 3.55% and 13.46% (N = 52), respectively. FISH proved to be more effective than karyotyping in the study as it could reveal cryptic mosaics in some cases where karyotyping initially failed to detect such a clone. We suggest adding FISH on different tissue than peripheral blood to verify sex-chromosome constitution, especially in cases with karyotypes: 45,X; mosaic 45,X/46,XX or 46,XY; 46,Xidic(Y) detected from blood; in children, where mosaic 45,X was detected prenatally but was not confirmed from peripheral blood. The correlation of short stature with the occurrence of SHOX mutations was insignificant and short stature demonstrates a low positive predictive value-15.5% as unique indicator for SHOX mutations. The typical skeletal signs of LWD, including Madelung deformity and disproportionate growth, positively correlate with the findings of pathogenic SHOX variants (p < 0.01) by Fisher’s exact test but not with the findings of VUS variants in SHOX which are more prevalent in the individuals with idiopathic short stature or in the individuals with normal height.

SHOX deficiency in children with growth impairment: evaluation of known and new auxological and radiological indicators

Background

The phenotypic features of SHOX deficiency (SHOX-D) are highly variable and can be very mild, especially in young children. The aim of this retrospective study was to evaluate auxological and radiological indicators that could be predictive of SHOX-D in children.

Methods

Molecular analysis of the SHOX gene was performed in 296 subjects with growth impairment or skeletal disproportion, without alternative diagnosis. Auxological variables and radiographs of the hand, wrist and forearm were evaluated.

Results

SHOX mutations (88% inherited, 12% de novo) were identified in 52 subjects. The most predictive auxological indicators of SHOX-D were an increased sitting height/height ratio and a decreased arm span/height ratio. The convexity of distal radial metaphysis at X-ray, not yet reported in literature, was also found to be predictive of SHOX-D. In young children, stratification of data by bone age also highlighted ulnar tilt, lucency of the ulnar border of the distal radius and enlarged radius as the radiological signs most related to SHOX-D .

Conclusions

In this study, the analysis of auxological and radiological indicators in SHOX-D children allowed to identify an additional early radiological sign and underlines the importance of family auxological evaluation.

Individuals with common diseases but with a low polygenic risk score could be prioritized for rare variant screening

PURPOSE

Identifying rare genetic causes of common diseases can improve diagnostic and treatment strategies, but incurs high costs. We tested whether individuals with common disease and low polygenic risk score (PRS) for that disease generated from less expensive genome-wide genotyping data are more likely to carry rare pathogenic variants.

METHODS

We identified patients with one of five common complex diseases among 44,550 individuals who underwent exome sequencing in the UK Biobank. We derived PRS for these five diseases, and identified pathogenic rare variant heterozygotes. We tested whether individuals with disease and low PRS were more likely to carry rare pathogenic variants.

RESULTS

While rare pathogenic variants conferred, at most, 5.18-fold (95% confidence interval [CI]: 2.32-10.13) increased odds of disease, a standard deviation increase in PRS, at most, increased the odds of disease by 5.25-fold (95% CI: 5.06-5.45). Among diseased patients, a standard deviation decrease in the PRS was associated with, at most, 2.82-fold (95% CI: 1.14-7.46) increased odds of identifying rare variant heterozygotes.

CONCLUSION

Rare pathogenic variants were more prevalent among affected patients with a low PRS. Therefore, prioritizing individuals for sequencing who have disease but low PRS may increase the yield of sequencing studies to identify rare variant heterozygotes.

Short Stature is Progressive in Patients with Heterozygous NPR2 Mutations

BACKGROUND

NPR2 encodes atrial natriuretic peptide receptor B (ANPRB), a regulator of skeletal growth. Biallelic loss-of-function mutations in NPR2 result in acromesomelic dysplasia Maroteaux type (AMDM; OMIM 602875), while heterozygous mutations may account for 2% to 6% of idiopathic short stature (ISS).

OBJECTIVE

Describe the physical proportions and growth characteristics of an extended family with novel NPR2 mutations including members with AMDM, ISS, or normal stature.

DESIGN AND PARTICIPANTS

We performed whole exome sequencing in 2 healthy parents and 2 children with AMDM. Detailed genotyping and phenotyping were performed on members of a multigenerational family in an academic medical center. We expressed mutant proteins in mammalian cells and characterized expression and function.

RESULTS

The sisters with AMDM were compound heterozygotes for missense mutations in the NPR2 gene, a novel p.P93S (maternal) and the previously reported p.R989L (paternal). Both mutant ANPRB proteins were normally expressed in HEK293T cells and exhibited dominant negative effects on wild-type ANPRB catalytic activity. Heterozygous relatives had proportionate short stature (height z-scores -2.06 ± 0.97, median ± SD) compared with their wild-type siblings (-1.37 ± 0.59). Height z-scores progressively and significantly decreased as NPR2-heterozygous children matured, while remaining constant in their wild-type siblings.

CONCLUSIONS

Biallelic NPR2 mutations cause severe skeletal dysplasia (AMDM), whereas heterozygous mutations lead to a subtler phenotype characterized by progressive short stature with by increasing loss of height potential with age.

Whole-Exome Sequencing in Idiopathic Short Stature: Rare Mutations Affecting Growth

Idiopathic short stature (ISS) is a common diagnosis of exclusion in patients with short stature (SS). In this article, we aimed to identify the genetic causes of SS in patients with ISS and investigate treatment options. Fourteen children with diagnosis of ISS were identified, and whole-exome sequencing (WES) was subsequently conducted on blood-derived DNA. Five patients were correctly diagnosed with ISS and four had rare mutations that have not been previously reported. Four patients had mutations known to cause SS and one had a mutation that was known not to affect height. WES can help identify rare mutations implicated in ISS.

Clinical and Genetic Characteristics of 23 Korean Patients with Haploinsufficiency of the Short-stature Homeobox-containing Gene

BACKGROUND

The short-stature homeobox-containing gene (SHOX) is one of the major growth genes in humans. The clinical spectrum of SHOX haploinsufficiency ranges from Léri-Weill dyschondrosteosis to idiopathic short stature. Herein, we describe the clinical and genetic characteristics of 23 Korean patients with SHOX deficiency disorders.

METHODS

Medical records of 23 patients (19 females and 4 males) from 15 unrelated families who were genetically confirmed to have SHOX deficiency were retrospectively reviewed. SHOX gene deletions or mutations were determined by sequence analyses using multiplex ligation-dependent probe amplification, chromosomal microarray, and/or Sanger sequencing methods.

RESULTS

In the 15 families, 9 probands were de novo cases. All 23 patients showed mesomelia. Madelung deformity and tibia vara were observed in 13 (56.5%) and 3 (13.1%) patients, respectively. Genetically, 11 (73.3%) of the 15 families showed SHOX deletions of various sizes, and the other 4 families harboured SHOX sequence variants. Four patients had undergone orthopaedic surgeries (3 for tibia vara and 1 for Madelung deformity). Among 7 patients who had received growth hormone treatment for ≥1 year, 5 showed good responses, with a median first-year change-in-height standard deviation score of +0.6. There were no significant differences in the clinical characteristics of the deletion and point mutation groups.

CONCLUSIONS

A high index of suspicion and the genetic confirmation of SHOX deficiency are helpful for the timely management of the condition and are needed to provide genetic counselling to the family members of the patients.

Metabolic syndrome coexists with adult Léri-Weill dyschondrosteosis: A case report

Léri-Weill dyschondrosteosis (LWD) is usually caused by haploinsufficiency of the short stature homeobox-containing gene (SHOX). The clinical manifestation of this disease is a classic triad, which are short stature, mesomelia and Madelung deformity. LWD also includes other features, such as high body mass index. Short stature and high body mass index are risk factors of type 2 diabetes mellitus and cardiovascular disease; however, LWD combined with type 2 diabetes mellitus or metabolic syndrome have not been described in the literature. In this article, we report a case of LWD caused by an M1T mutation of the start codon of the SHOX gene. The patient also had type 2 diabetes mellitus, hypertension and dyslipidemia. It is suggested that patients with LWD should be identified promptly, and the prevention and treatment of metabolic diseases and cardiovascular disease should be taken into consideration in patients with LWD.

Novel Clinical Criteria Allow Detection of Short Stature Homeobox-Containing Gene Haploinsufficiency Caused by Either Gene or Enhancer Region Defects

INTRODUCTION

Short stature homeobox-containing gene (SHOX) haploinsufficiency is associated with short stature, Madelung deformity and mesomelia. Current clinical screening tools are based on patients with intragenic variants or deletions. However, recent discoveries showed that deletions of the enhancer elements are quite common. The majority of these patients show less body disproportion and respond better to recombinant human growth hormone treatment. We redefined clinical criteria for genetic analysis to facilitate detection of the full spectrum of SHOX haploinsufficiency.

METHODS

We analyzed 51 children with SHOX variants or deletions and 25 children with a deletion in its enhancer region. Data were compared to 277 children referred for suspicion of growth failure without endocrine or genetic pathology.

RESULTS

Only half of the patients with an enhancer region deletion fulfilled any of the current screening criteria. We propose new clinical criteria based on sitting height to height ratio >1 SDS or arm span ≥3 cm below height, with a sensitivity of 99%. When these criteria are combined with obligatory short stature, the sensitivity to detect SHOX haploinsufficiency is 68.1%, the specificity 80.6%, and the number needed to screen 21 patients.

CONCLUSION

Novel clinical criteria for screening for SHOX haploinsufficiency allow the detection of patients within the full genetic spectrum, that is, intragenic variants and enhancer region deletions.

Variants in the 5'UTR reduce SHOX expression and contribute to SHOX haploinsufficiency

SHOX haploinsufficiency causes 70-90% of Léri-Weill dyschondrosteosis (LWD) and 2-10% of idiopathic short stature (ISS). Deletions removing the entire gene or enhancers and point mutations in the coding region represent a well-established cause of haploinsufficiency. During diagnostic genetic testing on ISS/LWD patients, in addition to classic SHOX defects, five 5'UTR variants (c.-58G > T, c.-55C > T, c.-51G > A, c.-19G > A, and c.-9del), were detected whose pathogenetic role was unclear and were thus classified as VUS (Variants of Uncertain Significance). The purpose of the present study was to investigate the role of these noncoding variations in SHOX haploinsufficiency. The variants were tested for their ability to interfere with correct gene expression of a regulated reporter gene (luciferase assay). The negative effect on the mRNA splicing predicted in silico for c.-19G > A was assayed in vitro through a minigene splicing assay. The luciferase assay showed that c.-51G > A, c.-19G > A, and c.-9del significantly reduce luciferase activity by 60, 35, and 40% at the homozygous state. Quantification of the luciferase mRNA showed that c.-51G > A and c.-9del might interfere with the correct SHOX expression mainly at the post-transcriptional level. The exon trapping assay demonstrated that c.-19G > A determines the creation of a new branch site causing an aberrant mRNA splicing. In conclusion, this study allowed us to reclassify two of the 5'UTR variants identified during SHOX diagnostic screening as likely pathogenic, one remains as a VUS, and two as likely benign variants. This analysis for the first time expands the spectrum of the genetic causes of SHOX haploinsufficiency to noncoding variations in the 5'UTR.

The Challenge of Defining and Investigating the Causes of Idiopathic Short Stature and Finding an Effective Therapy

Idiopathic short stature (ISS) comprises a wide range of conditions associated with short stature that elude the conventional diagnostic work-up and are often caused by still largely unknown genetic variants. In the last decade, the improvement of diagnostic techniques has led to the discovery of causal mutations in genes involved in the function of the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis as well as in growth plate physiology. However, many cases of ISS remain idiopathic. In the future, the more frequent identification of the underlying causes will allow a better stratification of subjects and offer a tailored management. GH therapy has been proposed and approved in some countries for the treatment of children with ISS. To improve the efficacy of GH therapy, trials with GH combined with GnRH agonists, aromatase inhibitors, and even IGF-I have been conducted. This review aims to revise the current definition of ISS and discuss the management of children with ISS on the basis of the most recent evidence.

Pathogenic/likely pathogenic variants in the SHOX, GHR and IGFALS genes among Indian children with idiopathic short stature

Background Our objective was to estimate the prevalence of pathogenic/likely pathogenic variants in the SHOX, GHR, and IGFALS genes among Indian children with idiopathic short stature (ISS), and assess the genotype-phenotype correlation. Methods We recruited 61 children with short stature, who were born appropriate for gestational age, had no obvious dysmorphism or disproportion, and in whom step-wise investigative work-up (including provocative growth hormone test) was normal. Multiplex ligation-dependent probe amplification was undertaken for identifying deletions/duplications in the SHOX gene. Bidirectional sequencing was performed for identifying variants in the SHOX and GHR genes in all, and for the IGFALS gene in those with serum insulin-like growth factor-1 (IGF-1) <-1 standard deviation. The genotype-phenotype correlation was studied. Results Four children (6.5%) had pathogenic heterozygous variants in the SHOX gene, with one child each having duplication of exon 5, splice site point variant c.278-1G > C in exon 3, partial deletion and complete deletion. None of the patients had pathogenic variants in the GHR gene. Of the 39 patients in whom the IGFALS gene was sequenced, novel heterozygous likely pathogenic variants were found in two children. One had the frameshift variant c.764_765insT, p.A265Gfs*114. The second had the missense variant c.1793G > A, p.R598H predicted by MutationTaster as 'disease causing', and indicated by the protein-modelling study as having compromised binding with IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) due to altered conformation of the interacting loop. Conclusions Pathogenic variants in the SHOX and IGFALS genes account for a significant proportion of Indian children with ISS. Further molecular studies using next generation sequencing are needed to gain insight into pathophysiological mechanisms and effective treatment strategies for ISS.

Towards a Rational and Efficient Diagnostic Approach in Children Referred for Growth Failure to the General Paediatrician

Based on a recent Dutch national guideline, we propose a structured stepwise diagnostic approach for children with growth failure (short stature and/or growth faltering), aiming at high sensitivity for pathologic causes at acceptable specificity. The first step is a detailed clinical assessment, aiming at obtaining relevant clinical clues from the medical history (including family history), physical examination (emphasising head circumference, body proportions and dysmorphic features) and assessment of the growth curve. The second step consists of screening: a radiograph of the hand and wrist (for bone age and assessment of anatomical abnormalities suggestive for a skeletal dysplasia) and laboratory tests aiming at detecting disorders that can present as isolated short stature (anaemia, growth hormone deficiency, hypothyroidism, coeliac disease, renal failure, metabolic bone diseases, renal tubular acidosis, inflammatory bowel disease, Turner syndrome [TS]). We advise molecular array analysis rather than conventional karyotyping for short girls because this detects not only TS but also copy number variants and uniparental isodisomy, increasing diagnostic yield at a lower cost. Third, in case of diagnostic clues for primary growth disorders, further specific testing for candidate genes or a hypothesis-free approach is indicated; suspicion of a secondary growth disorder warrants adequate further targeted testing.

GH successful treatment in a female with a de novo 46,XX,add(X)(p36),t(X;Y)(p36.3;p11.2), growth impairment and SHOX-haploinsufficiency

Children with chromosome translocations, concerning X chromosome, have a genetic pattern different from Turner syndrome; however, when a translocation involves the of part of X chromosome including short stature homeobox-containing Sex-determining Region Y gene, growth may be severely compromised.

We describe the clinical case of a 2.2-year-old-female, arrived at our paediatric unit for a decrease of height velocity. The karyotype was 46,XX,add(X)(p36.3). Array comparative genomic hybridization showed a fragment of Y chromosome, extended from 8.803.981 (Yp11.2) to 28.767.604 (Yq11.23). The final karyotype was 46,XX,add(X)(p36),t(X;Y)(p36.3;p11.2). Fluorescence in situ Hybridization analysis using Sex-determining Region Y probe revealed no signal on the derivative Y chromosome.

At the admittance, height was 84.5 cm (− 1.24 SDS); SPAN was 79 cm; sitting height: 72.4 cm; weight was 17.5 kg. Bone age was 1.2 years. Multiplex Ligation Probe Amplification showed a heterozygous deletion of the Short Stature Homeobox-containing gene and of the pseudoautosomal region-1. This result correlated with Leri-Weill Syndrome. She started Growth Hormone treatment, with a good response.

The case described shows a rare translocation, involving the X chromosome and including SHOX gene and the pseudoautosomal region-1. At our knowledge, this is the first case of a patient with a karyotype 46,XX,add(X)(p36),t(X;Y)(p36.3;p11.2) and Short Stature Homeobox-containing gene haploinsufficiency, successfully treated with Growth Hormone.

Heterozygous Deletion of the SHOX Gene Enhancer in two Females With Clinical Heterogeneity Associating With Skewed XCI and Escaping XCI

Skewed X-chromosome inactivation (XCI) plays an important role in the phenotypic heterogeneity of X-linked disorders. However, the role of skewed XCI in XCI-escaping gene SHOX regulation is unclear. Here, we focused on a heterozygous deletion of SHOX gene enhancer with clinical heterogeneity. Using SNP array, we detected that the female proband with Leri-Weill dyschondrosteosis (LWD) carried an 857 kb deletion on Xp22.3 (encompassing SHOX enhancer) and a 5,707 kb large-fragment deletion on Xq25q26. XCI analysis revealed that the X-chromosome with the Xq25q26 large-fragment deletion was completely inactivated, which forced the complete activation of the other X-chromosome carrying SHOX enhancer deletion. While the Xp22.3 deletion locates on the escaping XCI region, under the combined action of skewed XCI and escaping XCI, transcription of SHOX gene was mainly from the activated X-chromosome with SHOX enhancer defect, involving in the formation of LWD phenotype. Interestingly, this SHOX enhancer deletion was inherited from her healthy mother, who also demonstrated completely skewed XCI. However, the X-chromosome with SHOX enhancer deletion was inactivated, and the normal X-chromosome was activated. Combing with escaping XCI, her phenotype was almost normal. In summary, this study was a rare report of SHOX gene enhancer deletion in a family with clinical heterogeneity due to skewed inactivation of different X-chromosomes, which can help in the genetic counseling and prenatal diagnosis of disorders in females with SHOX defect.

SHOX Deficiency in Argentinean Cohort: Long-Term Auxological Follow-Up and a Family's New Mutation

A cohort study on the growth of 19 Argentinean children, aged 0 to 18 years, and 11 of their first-degree relatives with alterations in the SHOX gene or its regulatory regions is reported. Children are born shorter and experience a growth delay during childhood with a stunted pubertal growth spurt. Body disproportion, with a sitting height/height ratio above +2 standard deviation score (SDS), was already present as early as 2 years old. Hand length was normal. Shortening of the radius, with a length below -1.9 SDS, was the earliest and most frequent radiological sign detected as early as 45 days old. We found a previously unreported mutation in a family with a highly variable phenotype, the boy had a severe phenotype with a milder presentation in other affected members of the family. We conclude that body disproportion and a shorter radius length on X-ray are useful tools for selecting children to undergo SHOX molecular studies.

Co-occurrence of genomic imbalances on Xp22.1 in the SHOX region and 15q25.2 in a girl with short stature, precocious puberty, urogenital malformations and bone anomalies

Background

Mutations of SHOX represent the most frequent monogenic cause of short stature and related syndromes. The genetic alterations include point mutations and deletions/duplications spanning both SHOX and its regulatory regions, although microrearrangements are confined to either the downstream or upstream enhancers in many patients. Mutations in the heterozygous state have been identified in up to 60–80% of Leri-Weill Dyschondrosteosis (LWD; MIM #127300) and approximately 4–5% of Idiopathic Short Stature (ISS; MIM#300582) patients. Homozygous or compound heterozygous mutations as well as biallelic deletions of SHOX and/or the enhancer regions result in a more severe phenotype, which is known as Langer Mesomelic Dysplasia (LMD; MIM #249700).

Case presentation

A 17 year old girl, presented with severe short stature, growth hormone deficiency (GHD), precocious puberty, dorsal scoliosis, dysmorphisms and urogenital malformations. She was born with agenesis of the right tibia and fibula, as well as with a supernumerary digit on the left foot. Array comparative genomic hybridization (aCGH) analysis detected the presence of two distinct duplications on Xp22.1 flanking the SHOX coding sequence and involving its regulatory regions. An additional duplication of 1.6–2.5 Mb on 15q25.2 that included 13 genes was also identified. The girl was adopted and the parent’s DNA was not available to establish the origin of the chromosome imbalances.

Conclusions

The complex phenotype observed in our patient is probably the result of the co-occurrence of rearrangements on chromosomes Xp22.1 and 15q25.2. The duplicated region on 15q25.2 region is likely to contain dosage-sensitive genes responsible for some of the clinical features observed in this patient, whereas the extreme short stature and the skeletal anomalies are likely attributable to the comorbidity of GHD and copy number variants in the SHOX region.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0445-8) contains supplementary material, which is available to authorized users.

GH and IGF-1 Replacement in Children

In this chapter, we want to give an overview on what we have learned from more than 30 years ago on the use of recombinant human growth hormone (rhGH) and later recombinant human IGF-1 which was introduced for the treatment of short children and what are the safety issues concerned with this treatment. However, rhGH is used not solely in conditions where short stature is the consequence of GH deficiency but also in various disorders without a proven GH deficiency. In clinical studies, growth responses to various forms of rhGH therapy were analyzed, adding to our concept about the physiology of growth. Most patients under rhGH treatment show a considerable short-term effect; however, the long-term gain of height in a child obtained by a year-long treatment until final height remains controversial in some of the growth disorders that have been treated with rhGH or IGF-1. Today the first studies on the long-term safety of rhGH treatment have been published and raising some questions whether this treatment is similarly safe for all the patient groups treated with rhGH. Although there is a long-standing safety record for these hormone replacement therapies, in the face of the considerable costs involved, the discussion about the risk to benefit ratio is continuing. Newer developments of rhGH treatment include long-term preparations, which have only to be injected once a week. Although some of these drugs already have proven their non-inferiority to conventional rhGH treatment, we have to await further results to see whether they show improvements in treatment adherence of the patients and prove their long-term safety.

Dental and Maxillofacial Signs in Leri-Weill Dyschondrosteosis

One of the most common causes of short stature is a defect of the short stature homeobox-containing (SHOX) gene, which is located in pseudoautosomal region 1 on the distal end of the short arm of chromosomes Xp22.33 and Yp11.32. More than 300 different mutations in the SHOX gene responsible for short stature syndrome have been described. The phenotypic expression of SHOX haploinsufficiency is remarkably varied. The 3 typical clinical presentations, from least to most severe, are idiopathic short stature without skeletal malformations, Leri-Weill dyschondrosteosis (LWD), and Langer mesomelic dysplasia, which is believed to represent the homozygous form of LWD. Despite a higher prevalence in women, suggesting the potentiating action of high estrogen levels on the effects of SHOX deficiency, the syndrome was initially believed to have an autosomal pattern of inheritance. In reality, heterozygous SHOX mutations can be transferred from the Y to the X chromosome and vice versa. This phenomenon is called "the jumping SHOX gene" and corresponds to a pseudoautosomal dominant inheritance. LWD is characterized by mesomelic short stature and Madelung deformity defined by an upward and medial displacement of the radial joint surface, which restricts range of motion. Less specific dysmorphic signs associated with LWD, such as short hands and feet, scoliosis, or muscular hypertrophy, have been described. When reviewing the dental and maxillofacial signs, only limited and summary data (micrognathia and high arched palate) have been published in the literature. This report presents a case of LWD that highlights many other noteworthy dental and maxillofacial signs that are important to clearly identify and appropriately treat.

Children Born Small for Gestational Age: Differential Diagnosis, Molecular Genetic Evaluation, and Implications

Children born small for gestational age (SGA), defined as a birth weight and/or length below -2 SD score (SDS), comprise a heterogeneous group. The causes of SGA are multifactorial and include maternal lifestyle and obstetric factors, placental dysfunction, and numerous fetal (epi)genetic abnormalities. Short-term consequences of SGA include increased risks of hypothermia, polycythemia, and hypoglycemia. Although most SGA infants show catch-up growth by 2 years of age, ∼10% remain short. Short children born SGA are amenable to GH treatment, which increases their adult height by on average 1.25 SD. Add-on treatment with a gonadotropin-releasing hormone agonist may be considered in early pubertal children with an expected adult height below -2.5 SDS. A small birth size increases the risk of later neurodevelopmental problems and cardiometabolic diseases. GH treatment does not pose an additional risk.

SHOX gene deletion screening by FISH in children with short stature and Madelung deformity and their characteristics

Background The short stature homeobox-containing (SHOX) gene strongly affects height. Therefore, a better understanding of SHOX haploinsufficiency could be advantageous to early diagnosis and treatment. We investigated the rate of SHOX haploinsufficiency in patients of short stature and documented their anthropometric measurements. Methods Between 2010 and 2017, we evaluated 86 patients (70 females, 16 males; age 4.3-18 years) with clinical diagnoses of short stature and Madelung deformity (MD). Clinical abnormalities are presented for patients with MD with and without SHOX haploinsufficiency as determined by fluorescence in situ hybridisation (FISH). Results According to our inclusion criteria, 78 of 86 patients (70 females, 16 males) had short stature (height <-2.5 standard deviation [SD]) and a family history suggestive of short stature. Eight patients had short stature, a family history suggestive of short stature and MD. MD was obvious in eight children in radiographic examinations. Although five of these had no deletion of SHOX, three had deletion of this gene. The deletion detection rate was 37.5% in the individuals with short stature and MD, i.e. Leri-Weill dyschondrosteosis syndrome (LWS), whilst no deletions were detected in the individuals with only short stature. One individual responded well to growth hormone (GH) treatment for the first 2 years but then developed an intolerance with persistently elevated insulin-like growth factor-1 (IGF-1) levels. Conclusions As we likely missed cases due to our methodology, the routine analysis for SHOX screening should be firstly multiplex ligation-dependent probe amplification (MLPA). The incidence of MD may have been higher in the cohort if X-rays were performed in all individuals. GH treatment was not well tolerated in one case due to persistently elevated IGF-1 levels, and long-term evaluations of patients with SHOX deficiency are required.