The clinical management of children with achondroplasia in Italy: results of clinician and parent/caregiver surveys

PURPOSE

This study aimed to assess the real-world management of achondroplasia in Italy.

METHODS

Two online surveys addressed to (1) parents/caregivers of individuals with achondroplasia and (2) Italian clinicians managing individuals with achondroplasia were conducted to assess real-world perspectives on achondroplasia management. Both surveys collected data on either patient or clinician demographics, details on diagnoses and referrals, disease complications, and views/experiences with limb lengthening surgery.

RESULTS

In total, 42 parents/caregivers and 19 clinicians (from 18 hospitals) completed the surveys. According to parents/caregivers, achondroplasia diagnosis was most commonly made in the third trimester of gestation (55% of respondents), with a genetic test performed to confirm the diagnosis in all but one case. In contrast, the clinicians indicated that, while achondroplasia was typically suspected during the prenatal period (78%), diagnosis was more frequently confirmed postnatally (72%). Parents/caregivers reported that the greatest impact of achondroplasia-related complications occurred in their children between the ages of 2-5 years. The most significant complications were otitis, sleep apnoea, stenosis of the foramen magnum or pressure on the spinal cord, and hearing difficulties. Lengthening surgery had been presented as a treatment option to 92% of responding parents/caregivers, with 76% of clinicians viewing surgery favourably. Typically, clinicians' reasons for suggesting limb lengthening surgery were to improve patient quality of life, increase patient autonomy and self-acceptance, improve trunk-limb disproportion, short stature and walking, and ensure that all possible treatment options had been presented to the parents/caregivers.

CONCLUSION

This survey provides insight into the real-world management of individuals with achondroplasia in Italy.

Structural brain anomalies in Cri-du-Chat syndrome: MRI findings in 14 patients and possible genotype-phenotype correlations

INTRODUCTION

Cri-du-Chat Syndrome (CdCS) is a genetic condition due to deletions showing different breakpoints encompassing a critical region on the short arm of chromosome 5, located between p15.2 and p15.3, first defined by Niebuhr in 1978. The classic phenotype includes a characteristic cry, peculiar facies, microcephaly, growth retardation, hypotonia, speech and psychomotor delay and intellectual disability. A wide spectrum of clinical manifestations can be attributed to differences in size and localization of the 5p deletion. Several critical regions related to some of the main features (such as cry, peculiar facies, developmental delay) have been identified. The aim of this study is to further define the genotype-phenotype correlations in CdCS with particular regards to the specific neuroradiological findings.

PATIENTS AND METHODS

Fourteen patients with 5p deletions have been included in the present study. Neuroimaging studies were conducted using brain Magnetic Resonance Imaging (MRI). Genetic testing was performed by means of comparative genomic hybridization (CGH) array at 130 kb resolution.

RESULTS

MRI analyses showed that isolated pontine hypoplasia is the most common finding, followed by vermian hypoplasia, ventricular anomalies, abnormal basal angle, widening of cavum sellae, increased signal of white matter, corpus callosum anomalies, and anomalies of cortical development. Chromosomal microarray analysis identified deletions ranging in size from 11,6 to 33,8 Mb on the short arm of chromosome 5. Then, we took into consideration the overlapping and non-overlapping deleted regions. The goal was to establish a correlation between the deleted segments and the neuroradiological features of our patients.

CONCLUSIONS

Performing MRI on all the patients in our cohort, allowed us to expand the neuroradiological phenotype in CdCS. Moreover, possible critical regions associated to characteristic MRI findings have been identified.

Providing high-quality care remotely to patients with rare bone diseases during COVID-19 pandemic

During the COVID-19 outbreak, the European Reference Network on Rare Bone Diseases (ERN BOND) coordination team and Italian rare bone diseases healthcare professionals created the "COVID-19 Helpline for Rare Bone Diseases" in an attempt to provide high-quality information and expertise on rare bone diseases remotely to patients and healthcare professionals. The present position statement describes the key characteristics of the Helpline initiative, along with the main aspects and topics that recurrently emerged as central for rare bone diseases patients and professionals. The main topics highlighted are general recommendations, pulmonary complications, drug treatment, trauma, pregnancy, children and elderly people, and patient associations role. The successful experience of the "COVID-19 Helpline for Rare Bone Diseases" launched in Italy could serve as a primer of gold-standard remote care for rare bone diseases for the other European countries and globally. Furthermore, similar COVID-19 helplines could be considered and applied for other rare diseases in order to implement remote patients' care.

Bone involvement and mineral metabolism in Williams' syndrome

CONTEXT

The previous studies suggested a possible increased risk of hypercalcaemia and reduced bone mineral density (BMD) in Williams' syndrome (WS). However, an extensive study regarding bone metabolism has never been performed.

OBJECTIVE

To investigate bone health in young adults with WS.

DESIGN

Cross-sectional study.

SETTINGS

Endocrinology and Metabolic Diseases and Medical Genetic Units.

PATIENTS

29 WS young adults and 29 age- and sex-matched controls.

MAIN OUTCOME MEASURES

In all subjects, calcium, phosphorus, bone alkaline phosphatase (bALP), parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHVitD), osteocalcin (OC), carboxyterminal cross-linking telopeptide of type I collagen (CTX), 24-h urinary calcium and phosphorus, femoral-neck (FN) and lumbar-spine (LS) BMD and vertebral fractures (VFx) were assessed. In 19 patients, serum fibroblast growth factor-23 (FGF23) levels were measured.

RESULTS

WS patients showed lower phosphorus (3.1 ± 0.7 vs 3.8 ± 0.5 mg/dL, p = 0.0001) and TmP/GFR (0.81 ± 0.32 vs 1.06 ± 0.25 mmol/L, p = 0.001), and an increased prevalence (p = 0.005) of hypophosphoremia (34.5 vs 3.4%) and reduced TmP/GFR (37.9 vs 3.4%). Moreover, bALP (26.3 ± 8.5 vs 35.0 ± 8.0 U/L), PTH (24.5 ± 12.6 vs 33.7 ± 10.8 pg/mL), OC (19.4 ± 5.3 vs 24.5 ± 8.7 ng/mL), and FN-BMD (- 0.51 ± 0.32 vs 0.36 ± 0.32) were significantly lower (p < 0.05), while CTX significantly higher (401.2 ± 169.3 vs 322.3 ± 122.4 pg/mL, p < 0.05). Serum and urinary calcium and 25OHVitD levels, LS-BMD and VFx prevalence were comparable. No cases of hypercalcemia and suppressed FGF23 were documented. Patients with low vs normal phosphorus and low vs normal TmP/GFR showed comparable FGF23 levels. FGF23 did not correlate with phosphorus and TmP/GFR values.

CONCLUSIONS

Adult WS patients have reduced TmP/GFR, inappropriately normal FGF23 levels and an uncoupled bone turnover with low femoral BMD.

Characterization of multi-locus imprinting disturbances and underlying genetic defects in patients with chromosome 11p15.5 related imprinting disorders

The identification of multilocus imprinting disturbances (MLID) appears fundamental to uncover molecular pathways underlying imprinting disorders (IDs) and to complete clinical diagnosis of patients. However, MLID genetic associated mechanisms remain largely unknown. To characterize MLID in Beckwith-Wiedemann (BWS) and Silver-Russell (SRS) syndromes, we profiled by MassARRAY the methylation of 12 imprinted differentially methylated regions (iDMRs) in 21 BWS and 7 SRS patients with chromosome 11p15.5 epimutations. MLID was identified in 50% of BWS and 29% of SRS patients as a maternal hypomethylation syndrome. By next-generation sequencing, we searched for putative MLID-causative mutations in genes involved in methylation establishment/maintenance and found two novel missense mutations possibly causative of MLID: one in NLRP2, affecting ADP binding and protein activity, and one in ZFP42, likely leading to loss of DNA binding specificity. Both variants were paternally inherited. In silico protein modelling allowed to define the functional effect of these mutations. We found that MLID is very frequent in BWS/SRS. In addition, since MLID-BWS patients in our cohort show a peculiar pattern of BWS-associated clinical signs, MLID test could be important for a comprehensive clinical assessment. Finally, we highlighted the possible involvement of ZFP42 variants in MLID development and confirmed NLRP2 as causative locus in BWS-MLID.

Insight into the Pathology of a COL1A1 Signal Peptide Heterozygous Mutation Leading to Severe Osteogenesis Imperfecta

Osteogenesis imperfecta or "brittle bone disease" is a congenital disorder of connective tissue causing the bone to break easily. Around 85-90% of cases are due to autosomal dominant mutations in the genes encoding type I collagen, the major organic component of bone. Genotype-phenotype correlations have shown that quantitative defects of collagen type I lead to mild OI, whereas structural defects show a wide clinical range from mild to perinatal lethal. This may partially be explained by the type of amino acid substitution and the relative location in the domain structure. To fully understand the variability of the clinical manifestation and the underlying pathomechanisms, further investigations are required. Here we provide the first biochemical characterization of a mutation at the signal peptide cleavage site of COL1A1, a domain not yet characterized. By steady-state analysis, we observed reduced production of collagen type I. Furthermore, by pulse-chase analysis we detected delayed secretion and partial intracellular retention of collagen I. In the cellular fraction, the electrophoretic migration was abnormal; however, secreted type I collagen showed a normal migration pattern. The intracellular retention of collagen I was confirmed by immunofluorescent staining. Moreover, transmission electron microscopy of cultured fibroblasts revealed enlargement of ER cisternae. These results further support the hypothesis that mechanisms interfering with ER integrity play an important role in the pathology of severe OI.

Daily life changes and adaptations investigated in 154 families with a child suffering from a rare disability at a public centre for rare diseases in Northern Italy

BACKGROUND

Living with a disabled child has profound effects on the entire family. With a prevalence of developmental disabilities around 2,5 %, there is a considerable need to promote improvements in the health care system. Little is known about changes and adaptations in the lives of affected families and this paucity of information hinders the improvement of services. This study sought to explore the needs and changes in the everyday life of families with children suffering from rare diseases of varying severity, with and without mental disability. The aim was to measure the socio-demographic characteristics, health care problems and living conditions of a large cohort of families with an affected member.

METHODS

A sample of 154 families was recruited between September 2011 and April 2013 to respond to a 136 item questionnaire that explored different areas of concern (diagnosis and follow-up of clinical specialists, relationship with pediatrician, rehabilitation, school, work, institutional and/or private support, child care needs and family relationships).

RESULTS

All parents answered the questionnaire. They were satisfied with the services provided in particular for diagnosis and follow-up, relationships with the family pediatrician, rehabilitation services and school, regardless of the severity of condition, presence of intellectual disability (ID) or absence of diagnosis. Negative scores were reported for institutional and/or private support and family relationships in severe conditions.

CONCLUSIONS

The Health Care System should maintain a family-centered care and a multi-agency working, improving quality of life of families with disabled child to allow adaptation. At present these services are uncoordinated and financial support is poor, resulting in a heavy burden for these families.

Fetal growth patterns in Beckwith-Wiedemann syndrome

We provide data on fetal growth pattern on the molecular subtypes of Beckwith-Wiedemann syndrome (BWS): IC1 gain of methylation (IC1-GoM), IC2 loss of methylation (IC2-LoM), 11p15.5 paternal uniparental disomy (UPD), and CDKN1C mutation. In this observational study, gestational ages and neonatal growth parameters of 247 BWS patients were compared by calculating gestational age-corrected standard deviation scores (SDS) and proportionality indexes to search for differences among IC1-GoM (n = 21), UPD (n = 87), IC2-LoM (n = 147), and CDKN1C mutation (n = 11) patients. In IC1-GoM subgroup, weight and length are higher than in other subgroups. Body proportionality indexes display the following pattern: highest in IC1-GoM patients, lowest in IC2-LoM/CDKN1C patients, intermediate in UPD ones. Prematurity was significantly more prevalent in the CDKN1C (64%) and IC2-LoM subgroups (37%). Fetal growth patterns are different in the four molecular subtypes of BWS and remarkably consistent with altered gene expression primed by the respective molecular mechanisms. IC1-GoM cases show extreme macrosomia and severe disproportion between weight and length excess. In IC2-LoM/CDKN1C patients, macrosomia is less common and associated with more proportionate weight/length ratios with excess of preterm birth. UPD patients show growth patterns closer to those of IC2-LoM, but manifest a body mass disproportion rather similar to that seen in IC1-GoM cases.

ATRX mutation in two adult brothers with non-specific moderate intellectual disability identified by exome sequencing

In this report, we describe two adult brothers affected by moderate non-specific intellectual disability (ID). They showed minor facial anomalies, not clearly ascribable to any specific syndromic patterns, microcephaly, brachydactyly and broad toes. Both brothers presented seizures. Karyotype, subtelomeric and FMR1 analysis were normal in both cases.

We performed array-CGH analysis that revealed no copy-number variations potentially associated with ID. Subsequent exome sequence analysis allowed the identification of the ATRX c.109C>T (p.R37X) mutation in both the affected brothers. Sanger sequencing confirmed the presence of the mutation in the brothers and showed that the mother is a healthy carrier.

Mutations in the ATRX gene cause the X-linked alpha thalassemia/mental retardation (ATR-X) syndrome (MIM #301040), a severe clinical condition usually associated with profound ID, facial dysmorphism and alpha thalassemia. However, the syndrome is clinically heterogeneous and some mutations, including the c.109C>T, are associated with a broad phenotypic spectrum, with patients displaying a less severe phenotype with only mild-moderate ID. In the case presented here, exome sequencing provided an effective strategy to achieve the molecular diagnosis of ATR-X syndrome, which otherwise would have been difficult to consider due to the mild non-specific phenotype and the absence of a family history with typical severe cases.

De novo deletion of 1q31.1-q32.1 in a patient with developmental delay and behavioral disorders

We describe the case of a 6-year-old boy with a de novo deletion of the long arm of chromosome 1 encompassing band 1q31.1-q32.1, minor facial anomalies, mild developmental delay, and behavioral disorders. His postnatal karyotype was normal. Using array-comparative genomic hybridization, we identified and characterized a de novo 1q interstitial deletion of about 15.6 Mb, which partially overlaps those of other reported cases. We considered the gene content of the deleted region in an attempt to compare the clinical features of our patient with these other cases, even though they were not characterized molecularly in detail. The most remarkable difference was the absence of microcephaly. To the best of our knowledge, this is the first report of a de novo 1q31.1-q32.1 deletion. Moreover, it illustrates how molecular delineation associated with fine clinical characterization can improve the genotype-phenotype correlations of classical cytogenetic abnormalities.

Unmasking of a Recessive SCARF2 Mutation by a 22q11.12 de novo Deletion in a Patient with Van den Ende-Gupta Syndrome

Van den Ende-Gupta syndrome (VDEGS) is a congenital condition characterized by craniofacial and skeletal manifestations, specifically blepharophimosis, malar and maxillary hypoplasia, distinctive nose, arachnocamptodactyly, and long slender bones of the hands and feet. To date, only 24 patients have been described. It is generally thought that the syndrome is transmitted by an autosomal recessive mode of inheritance, although evidence for genetic heterogeneity has recently been presented. We report on a girl followed from birth up to 3 years of life with a set of peculiar minor anomalies, arachnocamptodactyly of hands and feet, characteristic of VDEGS in association with a 22q11.12 deletion. Recently, the VDEGS gene was mapped to the DiGeorge syndrome region on 22q11.2, and homozygous mutations in the SCARF2 gene were identified. We now report the first patient with VDEGS due to compound heterozygosity for the common 22q11.2 microdeletion and a hemizygous SCARF2 splice site mutation.

Phenotype of five cases of prenatally diagnosed campomelic dysplasia harboring novel mutations of the SOX9 gene

OBJECTIVES

Campomelic dysplasia is a rare congenital skeletal disorder characterized by bowing of the long bones and a variety of other skeletal and extraskeletal defects, many of which can now be identified prenatally using advanced ultrasound equipment. The disorder is caused by mutations in SRY-box 9 (SOX9), a gene that is abundantly expressed in chondrocytes as well as in other tissues. However, the correlation between genotype and phenotype is still unclear. We report five cases of prenatally detected campomelic dysplasia in which the diagnosis was confirmed by molecular analysis.

METHODS

Ultrasound examinations were performed between 12 and 32 weeks. Standard fetal biometric measurements were obtained. Fetal sex was determined sonographically and confirmed by chromosomal analysis. Genomic DNA was obtained in four cases before termination of pregnancy from chorionic villi or amniocytes and in one case postnatally from peripheral blood.

RESULTS

Skeletal dysplasia, most often limb shortening and bowed femora, was observed in one case in the first trimester, in three cases in the second trimester and in one case, presenting late for antenatal care, in the third trimester. Four of the pregnancies were terminated and one was carried to term. Postmortem/postnatal physical and radiographic examinations confirmed the presence of anomalies characteristic of campomelic dysplasia. A de novo mutation in the SOX9 gene was detected in all four cases that underwent termination. The father of the proband in the case that went to term was a carrier of a somatic mosaic mutation without clinical or radiographic signs of campomelic dysplasia.

CONCLUSIONS

It is likely that the integrated expertise of ultrasonographers, obstetricians, pediatricians and clinical geneticists will markedly improve the likelihood of accurate prenatal clinical diagnoses of campomelic dysplasia. This will, in turn, encourage more specific molecular testing and facilitate comprehensive genetic counseling.

Nasopharyngeal teratoma and diaphragmatic hernia: a non random association?

We describe a female affected by diaphragmatic hernia and nasopharyngeal teratoma. The case is compared with one already reported and possible diagnoses discussed. These cases appear to represent a new syndrome.

Maternal chromosome 7 hetero/isodisomy in Silver-Russell syndrome and PEG1 biallelic expression

Silver-Russell syndrome (SRS) is characterized by a severe intrauterine and postnatal growth retardation, relative macrocephaly associated with 'mild' facial anomalies. The diagnostic importance of skeletal asymmetry remains controversial. The aetiology of the syndrome is heterogeneous. Maternal uniparental disomy of chromosome 7 (mUPD7) has been reported in approximately 7% of patients, but two carriers of chromosomal abnormalities involving the band 17q25 have also been described. We investigated a clinically selected sample of 20 SRS patients for the presence of mUPD7 using polymorphic microsatellite markers spanning the whole chromosome. Maternal UPD7 was found in only one patient corresponding to an incidence of 5%. The allelic distribution in this patient was consistent with heterodisomy. Segregation analysis of chromosome 14 and 16 showed a biparental contribution in all the 20 patients. Blood RNA from the mUPD7 patient and a normal donor were evaluated for the expression of Paternally Expressed Gene (PEG1), an imprinted gene on chromosome 7q32. Biallelic expression of the gene in adult blood tissues was found in both samples. Our results confirm the causal role of mUPD7 in a minority of SRS patients.

Long-term hormone replacement therapy in two patients with Kabuki syndrome and growth hormone deficiency

The Kabuki syndrome is characterized by mental retardation (mild-to-moderate), skeletal anomalies, typical facial appearance and post-natal growth deficiency. The authors describe two patients with Kabuki syndrome and proven growth hormone deficiency. The first patient has been on GH replacement therapy for 4 years; the second for 11 years. On the basis of a sufficiently long follow-up period the Authors discuss the advisability of replacement therapy with growth hormone in patients with Kabuki syndrome.

Molecular characterization of FRAXE-positive subjects with mental impairement in two unrelated Italian families

The FRAXE fragile site, 600 Kb distal to the more common FRAXA, has been reported to be expressed in subjects with mild nonsyndromal mental retardation. Amplification of more than 200 GCC repeats associated with methylation of the adjacent CpG island at Xq28 is responsible for FRAXE fragility. We describe two unrelated, mentally retarded males identified during a screening for fragile X syndrome. Both index cases underwent FRAXE molecular analysis, following cytogenetic expression of the fra X site and negative FRAXA test. In family 1, we were able to investigate other 13 subjects over three generations, identifying two additional FRAXE-positive males, one with a fully mutated allele and one with a mosaic genotype. Detailed evaluation of physical traits and psychometric tests was performed on three retarded males from family 1 and the propositus from family 2. All of them were found to lack a definite phenotype, and showed different degrees of mental retardation. Slight mental retardation was evident in the mosaic male, suggesting that methylation might be an important determinant of mental impairment.