Turner syndrome and Xp deletions: clinical and molecular studies in 47 patients

Elevated levels of neutrophils with a pro-inflammatory profile in Turner syndrome across karyotypes

Turner syndrome (TS) presents with multiple karyotypes, including 45,X monosomy and variants such as isochromosomes and mosaicism, and is characterized by several co-morbidities, including metabolic conditions and autoimmunity. Here, we investigated the genomic landscapes across a range of karyotypes. We show that TS have a common autosomal methylome and transcriptome, despite distinct karyotypic variations. All TS individuals lacked the X chromosome p-arm, and XIST expression from the q-arm did not affect the autosomal transcriptome or methylome, highlighting the critical role of the missing p-arm with its pseudoautosomal region 1. Furthermore, we show increased levels of neutrophils and increased neutrophil activation. The increase in neutrophils was linked to TS clinical traits and to increased expression of the X-Y homologous gene TBL1X, suggesting a genetic basis, which may lead to neutrophil-driven inflammatory stress in TS. Identifying TS individuals with increased neutrophil activation could potentially mitigate the progression towards more severe metabolic issues.

Approach and Management of Pregnancies with Risk Identified by Non-Invasive Prenatal Testing

This study represents our second investigation into NIPT, involving a more extensive patient cohort with a specific emphasis on the high-risk group. The high-risk group was subsequently divided into two further groups to compare confirmed cases versus unconfirmed via direct methods. The methodology encompassed the analysis of 1400 consecutive cases from a single genetic center in western Romania, where NIPT was used to assess the risk of specific fetal chromosomal abnormalities. All high-risk cases underwent validation through direct analysis of fetal cells obtained via invasive methods, including chorionic villus sampling and amniocentesis. The confirmation process utilized QF-PCR, karyotyping, and SNP-Array methods customized to each case. Results: A high risk of aneuploidy at NIPT was identified in 36 out of 1400 (2.57%) cases and confirmed in 28 cases. The study also detected an increased risk for copy number variations (CNVs) in 1% of cases, confirmed in two instances involving one large microdeletion and one large microduplication. Trisomy 21 was the exclusive anomaly where NIPT confirmed all cases with identified risk. High-risk NIPT results which were not validated by invasive methods, were classified as false positives; parents in these cases determined to continue the pregnancy. In conclusion, NIPT can serve as a screening method for all pregnancies; however, in high-risk cases, an invasive confirmation test is strongly recommended.

The impact of amplification on quality of life in women with Turner syndrome

BACKGROUND

Individuals with Turner syndrome (TS, ORPHA 881) experience barriers in communication throughout life as they navigate both early conductive, and progressive sensorineural hearing loss amid other healthcare needs. Hearing loss is self-identified as one of the largest unmet healthcare needs.

PURPOSE

The purpose of this study was to investigate the impact of treatment for hearing loss on communication confidence and quality of life measures for individuals with TS.

RESEARCH DESIGN

We employed a prospective cross-sectional study design that included both online survey data and audiometric data for a subset of participants.

STUDY SAMPLE

We recruited 179 adults with TS at the Turner Syndrome Society of the United States (TSSUS) Conference, and through a variety of regional TS organizations' social media platforms. Audiological data was collected onsite at the conference for a subset of 67 participants; 8 of which who were followed after receiving subsequent treatment with hearing aids.

DATA COLLECTION AND ANALYSIS

The online survey design included demographic questions, the Communication Confidence Profile (CCP), and the RAND 36-Item Health Survey 1.0. Audiometric data included tympanometry, puretone air, and puretone bone conduction thresholds. Descriptive statistics, parametric, and non-parametric tests were used to analyze both survey and audiometric data.

RESULTS

74% of participants had a self-reported diagnosis of hearing loss, of which 61% were previously recommended amplification. Only 38% of participants reported using hearing aids. For those participants who wore hearing aids, Total CCP Score, 'Confidence in Ability to Hear Under Various Conditions', and 'Energy/Vitality' metrics were significantly greater than those with untreated hearing loss warranting a hearing aid. Collectively, Total CCP Score and 'Confidence in Ability to Hear Under Various Conditions' increased significantly when participants were fit with hearing aids.

CONCLUSION

The results support previous data where hearing loss is a self-identified healthcare concern among women with Turner syndrome, yet many fail to receive appropriate hearing evaluation or treatment. Additionally, the use of hearing aids may improve communication confidence and quality of life in women with Turner syndrome. Furthermore, this study confirms the need for long-term audiological care and monitoring in women with Turner syndrome.

Chromosomal Abnormalities of Interest in Turner Syndrome: An Update

Turner syndrome (TS) is caused by the total or partial loss of the second sex chromosome; it occurs in 1 every 2,500-3,000 live births. The clinical phenotype is highly variable and includes short stature and gonadal dysgenesis. In 1959, the chromosomal origin of the syndrome was recognized; patients had 45 chromosomes with a single X chromosome. TS presents numerical and structural abnormalities in the sex chromosomes, interestingly only 40% have a 45, X karyotype. The rest of the chromosomal abnormalities include mosaics, deletions of the short and long arms of the X chromosome, rings, and isochromosomes. Despite multiple studies to establish a relationship between the clinical characteristics and the different chromosomal variants in TS, a clear association cannot yet be established. Currently, different mechanisms involved in the phenotype have been explored. This review focuses to analyze the different chromosomal abnormalities and phenotypes in TS and discusses the possible mechanisms that lead to these abnormalities.

AMH and other markers of ovarian function in patients with Turner syndrome - a single center experience of transition from pediatric to gynecological follow up

Turner syndrome (TS) is a chromosomal disorder that affects about 1 in 2500 female births and is characterized by the partial or complete absence of the second X chromosome. Depending on karyotype, TS is associated with primary ovarian insufficiency (POI). Approximately 50% of girls with a mosaic 45, X/46, XX karyotype may enter puberty spontaneously, but only 5-10% of women with TS achieve pregnancy without egg donation. In this review, we will evaluate the clinical use of markers of ovarian function in TS patients. Based on longitudinal studies of serum concentrations of reproductive hormones as well as ovarian morphology in healthy females and patients with TS, we will evaluate how they can be applied in a clinical setting. This is important when counseling patients and their families about future ovarian function essential for pubertal development and fertility. Furthermore, we will report on 20 years of experience of transition from pediatric to gynecological and adult endocrinological care in our center at Rigshospitalet, Copenhagen, Denmark.

Ovarian dysfunction in women with Turner syndrome

Ovarian dysfunction is one of the most common features of women with Turner syndrome. In these women, oocyte apoptosis is markedly accelerated from the early stage of fetal life. Reduction in the number of germ cells disturbs primordial follicle development and thereby leads to the formation of streak gonads. There are three possible causes of accelerated germ cell loss in 45,X ovaries. First, chromosomal pairing failure due to X chromosomal aneuploidy is believed to induce meiotic arrest. Indeed, it has been suggested that the dosage of the X chromosome is more critical for the survival of the oocytes than for other cells in the ovary. Second, impaired coupling between oocytes and granulosa cells may also contribute to germ cell apoptosis. Previous studies have shown that 45,X ovaries may tend to lose tight junctions which are essential for intercellular interactions. Lastly, ovarian dysfunction in women with Turner syndrome is partly attributable to the reduced dosage of several genes on the X chromosome. Specifically, BMP15, PGRMC1, and some other genes on the X chromosome have been implicated in ovarian function. Further studies on the mechanisms of ovarian dysfunction are necessary to improve the reproductive outcomes of women with Turner syndrome.

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.

Metabolomic and lipidomic characterization of an X-chromosome deletion disorder in neural progenitor cells by UHPLC-HRMS

INTRODUCTION

Intellectual disorders involving deletions of the X chromosome present a difficult task in the determination of a connection between symptoms and metabolites that could lead to treatment options. One specific disorder of X-chromosomal deletion, Fragile X syndrome, is the most frequently occurring of intellectual disabilities. Previous metabolomic studies have been limited to mouse models that may not have sufficiently revealed the full biochemical diversity of the disease in humans.

OBJECTIVES

The primary objective of this study was to elucidate the human biochemistry in X-chromosomal deletion disorders through metabolomic and lipidomic profiling, using cells from a X-deletion patient as a representative case.

METHODS

Metabolomic and lipidomic analysis was performed by UHPLC-HRMS on neural progenitor (NP) cells isolated from an afflicted female patient versus normal neural progenitor cells.

RESULTS

Results showed perturbations in several metabolic pathways, including those of arginine and proline, that significantly impact both neurotransmitter generation and overall brain function. Coincidently, dysregulation was observed for lipids involved in both cellular structure and membrane integrity. The trends of observed metabolomic changes, as well as lipidomic profiling from identified features, are discussed.

CONCLUSION

The lipidomic and metabolomic profiles of NP cell samples exhibited significant differentiation associated with partial deletion of the X chromosome. These findings suggest that rare X-chromosomal deletion disorders are not only a mental disorder limited to alterations in local neuronal functions, but are also metabolic diseases.

Turner Syndrome Systematic Review: Spontaneous Thelarche and Menarche Stratified by Karyotype

BACKGROUND

Girls with Turner syndrome (TS) have a high incidence of primary ovarian insufficiency. Recent data show rates of spontaneous thelarche (ST) of 38% and spontaneous menarche (SM) of 15-16%, with higher rates in those with mosaicism.

SUMMARY

We systematically reviewed the literature for evidence regarding rates of ST and SM in TS and evaluated rates based on the type of chromosomal mosaicism. We searched MEDLINE via PubMed, Embase, and the Cochrane Database of Controlled Trials. Reference lists were screened. Studies reporting outcomes of ST and SM in girls with TS, diagnosed by genetic analysis, were included. Data was collected regarding study design, cohort type, cohort age, the number of participants with ST and SM, the individual age at diagnosis of ST and SM, the mean age of patients with ST and SM, sample size, the number of participants with secondary amenorrhea, and karyotype. Key Messages: In total 2,699 patients were assessed for ST and 2,890 for SM from 43 articles. Overall the rates of ST were 32% (95% CI 26.4-38.9) and SM 20.8% (95% CI 19.3-22.4). Girls with X monosomy had the lowest rates of ST (i.e., 13%; 95% CI 8.7-19.7) and SM (i.e., 9.1%; 95% CI 7.3-11.3). Girls with 45,X/47,XXX had the highest rates of ST (i.e., 88.1%; 95% CI 62-97.1) and SM (i.e., 66.2%; 95% CI 49.3-79.6).

CONCLUSIONS

Rates of ST and SM differ by karyotype in TS. When counseling patients, the karyotype should strongly influence discussions regarding pubertal development and the future reproductive potential.

Losing maleness: Somatic Y chromosome loss at every stage of a man's life

Mosaic loss of Y chromosome (LOY) is assumed to be among the most common acquired genetic variations in elderly people. Recent studies have linked aging-related mosaic LOY to the risk of Alzheimer's disease, cancer, and early death. Here, we propose that mosaic LOY can present in men at any age. Mosaic LOY appears to be associated with disorders of sex development and Turner syndrome at birth, short stature from childhood, and spermatogenic failure at reproductive age, in addition to shortened survival after 60 years of age.

Detection of mutually exclusive mosaicism in a girl with genotype-phenotype discrepancies

Discordance between clinical phenotype and genotype has multiple causes, including mosaicism. Phenotypes can be modified due to tissue distribution, or the presence of multiple abnormal cell lines with different genomic contributions. We have studied a 20-month-old female whose main phenotypes were failure to thrive, developmental delay, and patchy skin pigmentation. Initial chromosome and SNP microarray analysis of her blood revealed a non-mosaic ∼24 Mb duplication of 15q25.1q26.3 resulting from the unbalanced translocation of terminal 15q to the short arm of chromosome 15. The most common feature associated with distal trisomy 15q is prenatal and postnatal overgrowth, which was not consistent with this patient's phenotype. The phenotypic discordance, in combination with the patchy skin pigmentation, suggested the presence of mosaicism. Further analysis of skin biopsies from both hyper- and hypopigmented regions confirmed the presence of an additional cell line with the short arm of chromosome X deleted and replaced by the entire long arm of chromosome 15. The Xp deletion, consistent with a variant Turner Syndrome diagnosis, better explained the patient's phenotype. Parental studies revealed that the alterations in both cell lines were de novo and the duplicated distal 15q and the deleted Xp were from different parental origins, suggesting a mitotic event. The possible mechanism for the occurrence of two mutually exclusive structural rearrangements with both involving the long arm of chromosome 15 is discussed.

Novel loci for non-syndromic coarctation of the aorta in sporadic and familial cases

BACKGROUND

Coarctation of the aorta (CoA) accounts for 5-8% of all congenital heart defects. CoA can be detected in up to 20% of patients with Ullrich-Turner syndrome (UTS), in which a part or all of one of the X chromosomes is absent. The etiology of non-syndromic CoA is poorly understood. In the present work, we test the hypothesis that rare copy number variation (CNV) especially on the gonosomes, contribute to the etiology of non-syndromic CoA.

METHODS

We performed high-resolution genome-wide CNV analysis using the Affymetrix SNP 6.0 microarray platform for 70 individuals with sporadic CoA, 3 families with inherited CoA (n=13) and 605 controls. Our analysis comprised genome wide association, CNV burden and linkage. CNV was validated by multiplex ligation-dependent probe amplification.

RESULTS

We identified a significant abundance of large (>100 kb) CNVs on the X chromosome in males with CoA (p=0.005). 11 out of 51 (~ 22%) male cases had these large CNVs. Association analysis in the sporadic cohort revealed 14 novel loci for CoA. The locus on 21q22.3 in the sporadic CoA cohort overlapped with a gene locus identified in all familial cases of CoA (candidate gene TRPM2). We identified one CNV locus within a locus with high multipoint LOD score from a linkage analysis of the familial cases (SEPT9); another locus overlapped with a region implicated in Kabuki syndrome. In the familial cases, we identified a total of 7 CNV loci that were exclusively present in cases but not in unaffected family members.

CONCLUSION

Of all candidate loci identified, the TRPM2 locus was the most frequently implicated autosomal locus in sporadic and familial cases. However, the abundance of large CNVs on the X chromosome of affected males suggests that gonosomal aberrations are not only responsible for syndromic CoA but also involved in the development of sporadic and non-syndromic CoA and their male dominance.

Xp21 deletion in female patients with intellectual disability: Two new cases and a review of the literature

Xp21 continuous gene deletion syndrome is characterized by complex glycerol kinase deficiency (GK), adrenal hypoplasia congenital (NROB1), intellectual disability and/or Duchenne muscular dystrophy (DMD). The clinical features depend on the size of the deletion, as well as on the number and the nature of the encompassed genes. More than 100 male patients have been reported so far, while only a few cases of symptomatic female carriers have been described. We report here detailed clinical features and X chromosome inactivation analysis in two unrelated female patients with overlapping Xp21 deletions presenting with intellectual disability and inconstant muscular symptoms.

The lymphatic phenotype in Turner syndrome: an evaluation of nineteen patients and literature review

Turner syndrome is a complex disorder caused by an absent or abnormal sex chromosome. It affects 1/2000-1/3000 live-born females. Congenital lymphoedema of the hands, feet and neck region (present in over 60% of patients) is a common and key diagnostic indicator, although is poorly described in the literature. The aim of this study was to analyse the medical records of a cohort of 19 Turner syndrome patients attending three specialist primary lymphoedema clinics, to elucidate the key features of the lymphatic phenotype and provide vital insights into its diagnosis, natural history and management. The majority of patients presented at birth with four-limb lymphoedema, which often resolved in early childhood, but frequently recurred in later life. The swelling was confined to the legs and hands with no facial or genital swelling. There was only one case of suspected systemic involvement (intestinal lymphangiectasia). The lymphoscintigraphy results suggest that the lymphatic phenotype of Turner syndrome may be due to a failure of initial lymphatic (capillary) function.

The lymphatic phenotype in Turner syndrome: an evaluation of nineteen patients and literature review

Turner syndrome is a complex disorder caused by an absent or abnormal sex chromosome. It affects 1/2000-1/3000 live-born females. Congenital lymphoedema of the hands, feet and neck region (present in over 60% of patients) is a common and key diagnostic indicator, although is poorly described in the literature. The aim of this study was to analyse the medical records of a cohort of 19 Turner syndrome patients attending three specialist primary lymphoedema clinics, to elucidate the key features of the lymphatic phenotype and provide vital insights into its diagnosis, natural history and management. The majority of patients presented at birth with four-limb lymphoedema, which often resolved in early childhood, but frequently recurred in later life. The swelling was confined to the legs and hands with no facial or genital swelling. There was only one case of suspected systemic involvement (intestinal lymphangiectasia). The lymphoscintigraphy results suggest that the lymphatic phenotype of Turner syndrome may be due to a failure of initial lymphatic (capillary) function.

Frequency and types of chromosomal abnormalities in Turkish women with amenorrhea

STUDY OBJECTIVE

To estimate the frequency and the type of chromosomal abnormalities (CA) in patients with primary (PA) and secondary amenorrhea (SA).

DESIGN

This retrospective study was comprised of patients had been referred to our laboratory between 1990 to 2008 and designed as original article.

SETTING

Medical Faculty of Cukurova University in Turkey.

PARTICIPANTS

Chromosomal analysis was carried out on 393 patients with PA and SA that were referred to Cytogenetic laboratory of Medical Biology and Genetic Department, Faculty of Medicine, Çukurova University.

INTERVENTIONS

Lymphocyte culturing depended karyotyping.

MAIN OUTCOME MEASURES

Standard lymphocyte culturing procedure and karyotyping was performed to all samples.

RESULTS

PA and SA were identified in 393 patients. The karyotype was normal in 337 cases (85.8%) and abnormal in 56 (14.2%) patients. CAs were found in 54 (13.7%) and 2 (0.5%) of women with PA and SA, respectively. Females carrying rearrangements between autosomal and sex chromosomes were detected in 2% (8/393). The numerical abnormalities of the X chromosome were detected in 39.3% (22/56) (monosomy and mosaic). Structural abnormalities of the X and the other chromosomes were detected in 25.5% (13 of 56). Structural mosaicism of X chromosome was found in 5.4% (3 of 56). Male karyotype (46, XY) was found in 33.9% (19/56). The most frequently detected abnormality were X chromosome monosomies or mosaics.

CONCLUSIONS

Our study revealed that some causes of amenorrhea could be due to CAs. Therefore, cytogenetic study should be important test in the evaluation of patients with PA or SA. The most common abnormality seen is 45,X karyotype (monosomy X/Turner Syndrome) and its variants.

Microscopic chromosome Xp distal deletions--a challenging issue in prenatal genetic counseling

OBJECTIVE

A prenatal diagnosis of chromosome X short arm deletions may present a challenge in prenatal genetic counseling. We present clinical and molecular data of carriers of Xp distal deletions.

METHODS

We assessed prenatal and postnatal phenotypes of individuals from three families with large Xp distal deletions and from a fourth family with a small Xp distal deletion. The work-up included karyotyping, chromosomal microarray analysis, and assessment of the X inactivation pattern.

RESULTS

Five out of eight women with large deletions had a short stature (<3rd percentile). Subjects from one family had developmental and emotional problems. All female carriers with small deletions had markedly short stature, whereas the men had mildly short stature. Chromosomal microarray analysis revealed 11.7-19.3 Mb deletions in three families and a small ~1 Mb deletion in the fourth. The pseudoautosomal region 1 of the X chromosome was deleted in two families with large deletions. X inactivation was skewed in all tested cases with large deletions.

CONCLUSION

Xp distal deletions are mainly associated with short stature. Skewing of the abnormal X chromosome may attenuate the phenotype in cases with large deletions. We suggest that prenatal evaluation in such cases should include sonographic follow-up and assessment of the X inactivation pattern.

Low-level hyperinsulinism with hypoglycemic spells in an infant with mosaic Turner syndrome and mild Kabuki-like phenotype: a case report and review of the literature

BACKGROUND

Impaired glucose tolerance and type 2 diabetes are well-known features in patients with Turner syndrome. To the best of our knowledge, there is only one reported case of hyperinsulinemic hypoglycemia associated with a complex mosaic Turner syndrome available in the current literature.

PATIENT

We report on the case of a 13-month-old girl with a complex mosaic Turner genotype and mild hyperinsulinemic hypoglycemia responsive to diazoxide therapy.

RESULTS

Cytogenetic analyses showed two or possibly three cell lines. Sixty percent of the cell lines had a 45,X genotype and the rest had 46,XX with a marker ring chromosome. Diagnosis of a mosaic Turner syndrome and mild Kabuki-like phenotype was confirmed.

CONCLUSIONS

Despite the rareness of this case, clinicians should be aware of the possibility of hyperinsulinemic hypoglycemia in patients with Turner syndrome to prevent further brain damage caused by hypoglycemic episodes and seizures. Although the mechanism leading to hyperinsulinism in this condition is still unknown, the present report discusses this rare presentation and gives an overview on the current literature regarding this case.

Bicuspid aortic valve and aortic coarctation are linked to deletion of the X chromosome short arm in Turner syndrome

Background

Congenital heart disease (CHD) is a cardinal feature of X chromosome monosomy, or Turner syndrome (TS). Haploinsufficiency for gene(s) located on Xp have been implicated in the short stature characteristic of the syndrome, but the chromosomal region related to the CHD phenotype has not been established.

Design

We used cardiac MRI to diagnose cardiovascular abnormalities in four non-mosaic karyotype groups based on 50-metaphase analyses: 45,X (n=152); 46,X,del(Xp) (n=15); 46,X,del(Xq) (n=4); and 46,X,i(Xq) (n=14) from peripheral blood cells.

Results

Bicuspid aortic valves (BAV) were found in 52/152 (34%) 45,X study subjects and aortic coarctation (COA) in 19/152 (12.5%). Isolated anomalous pulmonary veins (APV) were detected in 15/152 (10%) for the 45,X study group, and this defect was not correlated with the presence of BAV or COA. BAVs were present in 28.6% of subjects with Xp deletions and COA in 6.7%. APV were not found in subjects with Xp deletions. The most distal break associated with the BAV/COA trait was at cytologic band Xp11.4 and ChrX:41,500 000. One of 14 subjects (7%) with the 46,X,i(Xq) karyotype had a BAV and no cases of COA or APV were found in this group. No cardiovascular defects were found among four patients with Xq deletions.

Conclusions

The high prevalence of BAV and COA in subjects missing only the X chromosome short arm indicates that haploinsufficiency for Xp genes contributes to abnormal aortic valve and aortic arch development in TS.

Response to three years of growth hormone therapy in girls with Turner syndrome

PURPOSE

Short stature is the most common finding in patients with Turner syndrome. Improving the final adult height in these patients is a challenge both for the patients and physicians. We investigated the clinical response of patients to growth hormone treatment for height improvement over the period of three years.

METHODS

Review of medical records from 27 patients with Turner syndrome treated with recombinant human growth hormone for more than 3 years was done. Differences in the changes of height standard deviation scores according to karyotype were measured and factors influencing the height changes were analyzed.

RESULTS

The response to recombinant human growth hormone was an increase in the height of the subjects to a mean value of 1.1 standard deviation for subjects with Turner syndrome at the end of the 3-year treatment. The height increment in the first year was highest. The height standard deviation score in the third year was negatively correlated with the age at the beginning of the recombinant human growth hormone treatment. Different karyotypes in subjects did not seem to affect the height changes.

CONCLUSION

Early growth hormone administration in subjects with Turner syndrome is helpful to improve height response to the treatment.

Critical role of Yp inversion in PRKX/PRKY-mediated Xp;Yp translocation in a patient with 45,X testicular disorder of sex development

45,X testicular disorder of sex development (TDSD), previously known as 45,X maleness, with unbalanced Xp;Yp translocation is an extremely rare condition caused by concomitant occurrence of loss of an X chromosome of maternal origin and an aberrant Xp;Yp translocation during paternal meiosis. We identified a Japanese male infant with an apparently 45,X karyotype who exhibited chondrodysplasia punctata and growth failure. Cytogenetic analysis revealed a 45,X.ish der(X)t(X;Y)(p22.33;p11.2)(DXZ1+,SRY+) karyotype. Array comparative genome hybridization analysis showed a simple Xp terminal deletion involving SHOX and ARSE with the breakpoint just centromeric to PRKX, and an apparently complex Yp translocation with the middle Yp breakpoint just telomeric to PRKY and the centromeric and the telomeric Yp breakpoints around the long inverted repeats for the generation of a common paracentric Yp inversion. Subsequently, a long PCR product was obtained with an X-specific and a Y-specific primers that were designed on the assumption of the presence of a Yp inversion that permits the alignment of PRKX and PRKY in the same direction, and the translocation fusion point was determined to reside within a 246 bp X-Y homologous segment at the "hot spot A" in the 5' region of PRKX/PRKY, by sequential direct sequencing for the long PCR product. These results argue not only for the presence of rare 45,X-TDSD with Xp;Yp translocation, but also for a critical role of a common paracentric Yp inversion in the occurrence of PRKX/PRKY-mediated unbalanced Xp;Yp translocation.

Functional analysis of conserved non-coding regions around the short stature hox gene (shox) in whole zebrafish embryos

BACKGROUND

Mutations in the SHOX gene are responsible for Leri-Weill Dyschondrosteosis, a disorder characterised by mesomelic limb shortening. Recent investigations into regulatory elements surrounding SHOX have shown that deletions of conserved non-coding elements (CNEs) downstream of the SHOX gene produce a phenotype indistinguishable from Leri-Weill Dyschondrosteosis. As this gene is not found in rodents, we used zebrafish as a model to characterise the expression pattern of the shox gene across the whole embryo and characterise the enhancer domains of different CNEs associated with this gene.

METHODOLOGY/PRINCIPAL FINDINGS

Expression of the shox gene in zebrafish was identified using in situ hybridization, with embryos showing expression in the blood, putative heart, hatching gland, brain pharyngeal arch, olfactory epithelium, and fin bud apical ectodermal ridge. By identifying sequences showing 65% identity over at least 40 nucleotides between Fugu, human, dog and opossum we uncovered 35 CNEs around the shox gene. These CNEs were compared with CNEs previously discovered by Sabherwal et al., resulting in the identification of smaller more deeply conserved sub-sequence. Sabherwal et al.'s CNEs were assayed for regulatory function in whole zebrafish embryos resulting in the identification of additional tissues under the regulatory control of these CNEs.

CONCLUSION/SIGNIFICANCE

Our results using whole zebrafish embryos have provided a more comprehensive picture of the expression pattern of the shox gene, and a better understanding of its regulation via deeply conserved noncoding elements. In particular, we identify additional tissues under the regulatory control of previously identified SHOX CNEs. We also demonstrate the importance of these CNEs in evolution by identifying duplicated shox CNEs and more deeply conserved sub-sequences within already identified CNEs.

Apparent neotelomere in a 46,X,del(X)(qter→p11.2:)/46,X,rea(X)(qter→p11.2::q21.2→qter) novel mosaicism: review of 34 females with a recombinant-like dup(Xq) chromosome

A 26-year-old woman with secondary amenorrhea and turneroid stigmata was found to have a 46,X,rea(X)(qter→p11.2::q21.2→qter)/46,X,del(X)(qter→p11.2:) mosaicism in 101 G-banded metaphases (71 and 30, respectively). The mother's karyotype was normal (the father was already deceased). A fully skewed inactivation of both abnormal X-chromosomes was documented in RBG-banded metaphases and by means of the HUMARA assay. In addition, the latter revealed that the involved X-chromosome was the paternal one. The patient's secondary amenorrhea and turneroid stigmata can reliably be ascribed to her nearly complete Xp deletion present in all cells. Thus, this observation is consistent with the well-known gradation of ovarian function depending on the Xp deletion size. We assume that the first event was an intrachromosome recombination during paternal meiosis between paralogous sequences at Xp11.2 and Xq21.2, which resulted in a fertilizing rea(X) spermatozoid. Early in embryogenesis, the rea(X) dissociated at the Xp11.2 junction point to originate the del(X), which in turn was healed by the de novo addition of telomeric repeats (the acentric Xq21.2→qter segment was lost in the process). The reverse sequence appears unlikely because it implies that the del(X) chromosome was healed only after it undergone a postzygotic interchromatid recombination and apposite segregation required to obtain the rea(X) clone. The present observation further expands the cytogenetic heterogeneity in Turner syndrome and may represent another instance of a terminal deletion healed by the de novo addition of telomeric repeats.

FMR1 gene expansion, large deletion of Xp, and skewed X-inactivation in a girl with mental retardation and autism

We describe a girl with mild facial anomalies, mild mental retardation, and atypical autism with a remarkable behavioral phenotype of persistent anger, aggression, and dysphoria. The occurrence of late-onset tremor and premature ovarian failure in the maternal branch of the family pointed to a possible defect in the FMR1 gene. Indeed, the patient carried a full FMR1 mutation. Unexpectedly, both alleles of the gene were almost completely methylated. Cytogenetic examination of the patient revealed in addition a large de novo deletion in band Xp22 on one of her X chromosomes. The deletion was fine mapped using oligonucleotide array CGH, and its breakpoints were localized using sequencing. The size of the deletion was about 17.4 Mb, and it contained more than 90 protein-coding genes. Microsatellite analysis indicated paternal origin of the aberrant chromosome. The large rearrangement was the most probable cause of the X-inactivation skewing, thus explaining the methylation of not only the expanded (maternal) but also the normal (paternal) FMR1 alleles. This pattern of skewed X-inactivation was confirmed using the analysis of methylation at the AR locus. The relatively mild phenotype of the patient resulted most likely from unmasking of the FMR1 defect. Although the deleted region contained many important genes, the phenotypic contribution of the rearranged X chromosome was probably limited by its almost complete inactivation. However, reduced dose of several genes escaping X-inactivation might also play a role in the phenotype of the patient.

Unbalanced translocation in an adult patient with premature ovarian failure and mental retardation detected by spectral karyotyping and array-comparative genomic hybridization

BACKGROUND

There are only three cases of unbalanced translocation (X;1) reported in childhood in the literature, while no such phenotypic information is available in adults.

MATERIALS AND METHODS

To delineate the phenotype-genotype relationship of unbalanced translocation (X;1) in adulthood, we reported here a 20-year-old female with an unbalanced translocation (X;1) which was determined by spectral karyotyping, array-comparative genomic hybridization and subtelomeric fluorescence in situ hybridization (FISH).

RESULTS

The phenotype of partial trisomy 1 and partial monosomy X of the present case was much attenuated, including premature ovarian failure, mental retardation, class I obesity, mild dysmorphism and delayed secondary sexual characteristics. The breakpoints of the unbalanced translocation were accurately located at Xq28 and 1q32.1. The large amplification on Chromosome 1 q arm was found to involve 312 genes and the deletion on Chromosome X q arm also involved 141 genes. Overall, genes associated with physiological process (47 genes), cellular process (33), development (23), response to stimulus (1) and reproduction (1) were observed in the amplification on Chromosome 1 q arm. In addition, genes related to physiological process (23 genes), cellular process (13), development (6) and response to stimulus (2) were observed in the large deletion on chromosome X q arm. Late-replication studies revealed the existence of skewed X inactivation in the derivative X chromosome.

CONCLUSIONS

The phenotype of partial monosomy X and partial trisomy 1q is much attenuated in case of unbalanced translocation (X;1) in adulthood probably owing to skewed X inactivation in derivative X chromosome.

BMP15 mutations associated with primary ovarian insufficiency cause a defective production of bioactive protein

Bone morphogenetic protein-15 (BMP15) is selectively synthesized by oocytes as a pre-proprotein and is considered an ovarian follicle organizer whose adequate function is critical for female fertility. Missense mutations were reported in primary ovarian insufficiency (POI) but their biological impact remained unexplored. Here, screening of 300 unrelated idiopathic overt POI women with primary or secondary amenorrhea (SA) led to the identification of six heterozygous BMP15 variations in 29 of them. All alterations are nonconservative and include one insertion of three nucleotides (p.L262_L263insL) and five missense substitutions. Except for the p.S5R located in the signal sequence, the other variants (p.R68W, p.R138H, p.L148P, and p.A180T) localize in the proregion, which is essential for the processing and secretion of bioactive dimers. The mutations p.R68W, p.L148P, and the novel p.R138H lead to marked reductions of mature protein production. Their biological effects, evaluated by a novel luciferase-reporter assay in a human granulosa cell (GC) line, were significantly reduced. Cotransfection experiments of defective mutants with equal amounts of wild-type BMP15 cDNA, thus reproducing the heterozygous state seen in patients, did not generate a complete recovery of wild-type activity. No or minor deleterious effects were detected for the variants p.L262_L263insL, p.A180T, or p.S5R. In conclusion, heterozygous BMP15 mutations associated with the early onset of overt POI lead to defective secretion of bioactive dimers. These findings support the concept that an adequate amount of BMP15 secreted in the follicular fluid is critical for female fertility. We propose to consider the screening of BMP15 mutations among the analyses for the prediction of POI risk.

A patient with de-novo partial deletion of Xp (p11.4-pter) and partial duplication of 22q (q11.2-qter)

We report on a girl with partial deletion of Xp and partial duplication of 22q. Family studies demonstrate that both the patient's mother and her nonidentical twin sister carry the corresponding balanced translocation; 46,X,t(X;22)(p11.4;q11.2). This girl has developmental delay, microcephaly, mild dysmorphisms and hearing loss but otherwise shows few of the features described in individuals with duplications of the long arm of chromosome 22. She does manifest characteristics, such as short stature and biochemical evidence of ovarian failure, which are seen in partial or complete Xp deletions and Turner's syndrome.

A Turner syndrome neurocognitive phenotype maps to Xp22.3

BACKGROUND

Turner syndrome (TS) is associated with a neurocognitive phenotype that includes selective nonverbal deficits, e.g., impaired visual-spatial abilities. We previously reported evidence that this phenotype results from haploinsufficiency of one or more genes on distal Xp. This inference was based on genotype/phenotype comparisons of individual girls and women with partial Xp deletions, with the neurocognitive phenotype considered a dichotomous trait. We sought to confirm our findings in a large cohort (n = 47) of adult women with partial deletions of Xp or Xq, enriched for subjects with distal Xp deletions.

METHODS

Subjects were recruited from North American genetics and endocrinology clinics. Phenotype assessment included measures of stature, ovarian function, and detailed neurocognitive testing. The neurocognitive phenotype was measured as a quantitative trait, the Turner Syndrome Cognitive Summary (TSCS) score, derived from discriminant function analysis. Genetic analysis included karyotyping, X inactivation studies, fluorescent in situ hybridization, microsatellite marker genotyping, and array comparative genomic hybridization.

RESULTS

We report statistical evidence that deletion of Xp22.3, an interval containing 31 annotated genes, is sufficient to cause the neurocognitive phenotype described by the TSCS score. Two other cardinal TS features, ovarian failure and short stature, as well as X chromosome inactivation pattern and subject's age, were unrelated to the TSCS score.

CONCLUSION

Detailed mapping suggests that haploinsufficiency of one or more genes in Xp22.3, the distal 8.3 megabases (Mb) of the X chromosome, is responsible for a TS neurocognitive phenotype. This interval includes the 2.6 Mb Xp-Yp pseudoautosomal region (PAR1). Haploinsufficiency of the short stature gene SHOX in PAR1 probably does not cause this TS neurocognitive phenotype. Two genes proximal to PAR1 within the 8.3 Mb critical region, STS and NLGN4X, are attractive candidates for this neurocognitive phenotype.

Le syndrome de Turner☆☆Cet article est publié en partenariat avec Orphanet et disponible sur le site www.orpha.net. © 2007 Orphanet. Publié par Elsevier Masson SAS. Tous droits réservés

Turner syndrome occurs in 1:5000 live births (1:2,500 females) and is caused not only by X-chromosome monosomy, but also in a large degree, by the presence of a mosaicism (45,X) and/or an abnormal X or Y chromosome (deletion, isochromosome X, dicentric chromosome). Clinical features are heterogeneous and typical physical anomalies are often mild or absent. In all cases, patients are short but final height has been improved by growth hormone therapy. Ovarian failure, with variable onset depending on the chromosomal anomalies, is frequent. Others visceral diseases (bone anomalies, lymphedema, deafness, and cardiovascular, thyroid, gastrointestinal diseases) are less common and need a screening at diagnosis, then a survey during adolescence and adulthood. During gestation, typical forms can be diagnosed by ultrasound examination, but mild forms are discovered incidentally during amniocentesis for unrelated reasons (advanced maternal age) and prenatal advice is difficult. The quality of life and social life is better when puberty is not induced too late, and in absence of cardiac disease or deafness. Deafness can lead to learning difficulties and, during adulthood, sterility can have a negative effect on quality of life. The prognosis depends on heart diseases, obesity, arterial hypertension and osteoporosis. Therefore, a long-term follow-up is necessary.

Optimising management in Turner syndrome: from infancy to adult transfer

Turner syndrome can be defined as loss or abnormality of the second X chromosome in at least one cell line in a phenotypic female. The condition occurs in approximately 1 in every 2000 live female births,(1) so that in the UK the prevalence for any year of life is in the region of 200 girls. The condition is much more common in utero, it being estimated that 1-2% of all conceptuses are affected, of whom only 1% will survive to term.

A clinical and molecular study of 26 females with Xp deletions with special emphasis on inherited deletions

We have undertaken a clinical study of 26 females with deletions of Xp including five mother-daughter pairs. Cytogenetic and molecular analyses have mapped the breakpoints of the deletions. We determined the parental origin of each abnormality and studied the X-inactivation patterns. We describe the clinical features and compare them with the amount of Xp material lost. We discuss the putative loci for features of Turner syndrome and describe how our series contributes further to their delineation. We conclude that (1) fertility can be retained even with the loss of two-thirds of Xp, thus, if there are genes on Xp for ovarian development, they must be at Xp11-Xp11.2; (2) in our sample of patients there is no evidence to support the existence of a single lymphogenic gene on Xp; (3) there is no evidence for a second stature locus in proximal Xp; (4) there is no evidence to support the existence of a single gene for naevi; (5) we suggest that the interval in Xp21.1-Xp11.4 between DXS997 and DXS1368 may contain a gene conferring a predisposition to hypothyroidism.

Microdeletion in the SHOX 3' region associated with skeletal phenotypes of Langer mesomelic dysplasia in a 45,X/46,X,r(X) infant and Leri-Weill dyschondrosteosis in her 46,XX mother: implication for the SHOX enhancer

It is known that SHOX nullizygosity results in Langer mesomelic dysplasia (LMD) and SHOX haploinsufficiency leads to Leri-Weill dyschondrosteosis (LWDC). Here, we report on a microdeletion in the SHOX 3' region identified in a Japanese infant with LMD-compatible skeletal features and a 45,X[191]/46,X,r(X)(p22.3q24)[9] karyotype and in her mother with LWDC-compatible skeletal features and a normal 46,XX karyotype. Physical and auxological examinations revealed mesomelic appearance, ulnarly deviated hands, and borderline micrognathia in the infant, and relatively short forearms and lower legs in the mother. Radiological studies indicated mesomelia, markedly curved radii, hypoplastic ulnas and fibulas, and metaphyseal splaying in the infant, and borderline to mild curvature of the radii, decreased carpal angles, and high-normal triangularization index in the mother. Cytogenetic and molecular studies showed that the ring X chromosome of the infant was missing SHOX and of paternal origin, whereas the cytogenetically normal X chromosomes of the infant and one of the two X chromosomes of the mother, though they retained SHOX with normal coding sequences, had a microdeletion in the SHOX 3' region. The microdeletion started from a position approximately 200 kb from SHOX coding sequences, and spanned 240-350 kb in physical length involving DXYS233. The results, in conjunction with those reported by Flanagan et al. [2002], suggest that a cis-acting enhancer exists in the SHOX 3' region around DXYS233.

Cardiovascular anomalies in children and young adults with Ullrich-Turner syndrome the Erlangen experience

BACKGROUND

Females with Ullrich-Turner syndrome (UTS) have typical clinical features such as short stature, ovarian failure, visible dysmorphic stigmata, and abnormalities in different organs such as kidney or heart.

HYPOTHESIS

The aim of the present study was to analyze the distribution, prevalence, and relative risk of cardiovascular anomalies (CVA) in females with Ullrich-Turner syndrome (UTS) seen at one single center compared with that of the regional Bavarian population.

METHODS

The associations between CVA and karyotype were determined. In all, 117 girls and women with UTS, aged between 3 and 43 years (median 17.4 years) were studied retrospectively. The detailed cardiologic status including echocardiography was available in all patients. The prevalences of each cardiovascular anomaly were determined. On the basis of published epidemiologic data of CVA in Bavarian children, we assessed the relative risks of each CVA.

RESULTS

Thirty-five (29.9%) girls with UTS had at least one CVA. In all of these CVAs, coarctation of the aorta and bicuspid aortic valve occurred most often (18.5% each). The aortic malformations represented over two-thirds of all CVA (72.8%), whereas anomalies of the septum (8.6%), mitral valve (6.2%), pulmonary veins (4.9%), and other locations together accounted for the other third. Bicuspid aortic valve and partial anomalous pulmonary venous drainage were associated with the highest relative risk (RR) (3603 and 1293, respectively) compared with the Bavarian population. The overall RR of CVA was 48.7. Of the 117 girls and women examined, 64 (54.7%) had complete monosomy 45 X.

CONCLUSIONS

Our data demonstrate that about every third female with UTS is affected with at least one CVA, mainly left sided and associated with aortic structures. Our results underline the necessity of thorough cardiologic evaluation.

Selected enquiries into the causation of premature ovarian failure

In most species, reproductive senescence can be explained in the same general terms as physiological senescence. In fact, in some species rapid physiological senescence occurs on the completion of reproduction. The programme in women is unusual in that ovarian function comes to a relatively abrupt halt at 45-50 years of age, when the impact of somatic senescence on most other functions is minimal. Early reproductive senescence has been reported in other species (chimpanzees, macaques and toothed whales) but it is more attenuated and less abrupt. The proximate cause of physiological menopause seems to be oocyte depletion, but less obvious neuroendocrine changes precede or result from the gradual loss of oocytes. This is not surprising as many age-specific processes are controlled by hormones. Hormones provide a way for an animal to co-ordinate the ageing of different tissues. The failure to comprehend completely the reasons for the biological uniqueness of women makes the study of the more extreme examples of premature ovarian failure an important exercise. The premature loss of ovarian function in certain eukaryotic women highlights the role of those special maintenance and repair systems that must be functional in the selection process for healthy germ cells. The purpose of this article is to indicate selected areas of clinical and basic investigation that may provide clues to the mechanisms of untimely ageing of the human ovary. Studies of those human extremes with premature loss, or extended ovarian function, may provide critical insights into the unique discordance between somatic and reproductive senescence that is characteristic of normal women.

A familial Xp+ chromosome detected during fetal karyotyping, which is associated with short stature in four generations of a Turkish family

The short-stature homeobox-containing gene (SHOX) on chromosome Xp22.3 was recently identified as an important determinant of the stature phenotype. Deletions of the SHOX gene, some of them due to structural chromosome abnormalities, have been described in patients with idiopathic short stature and Leri-Weill syndrome. Additionally, haploinsufficiency of SHOX is a main cause for short stature seen in patients with Turner syndrome. Here we report an unusual X-chromosome abnormality, which was detected during a fetal karyotyping performed because of a previous child with Down syndrome. GTG banding demonstrated an extra chromosome segment on the terminal part of the short arm of chromosome X in the index case (karyotype: 46,X,Xp+). The same chromosomal abnormality was found in the mother and the maternal grandmother. All carriers of this chromosomal abnormality presented with short stature but no other associated symptoms. Whole chromosome painting of X revealed a homogeneous painting of the abnormal X chromosome indicating that no other chromosome was involved. Additional FISH studies with probe DXS1140 (Kallmann probe at Xp22.3), Quint-Essential X-Specific DNA (DMD probe at Xp21.2), XIST (at Xq13.2), and Tel Xq/Yq were performed, and no abnormality was observed in the intensities or the localizations of the probes signals. However, applying a specific SHOX gene probe (derived from cosmid LLNONO3M34F5) showed a loss of signal on the derivative X chromosome. Our results show that the Xp+ generation led to a deletion of the complete SHOX gene and caused short stature in the presented family.

Turner syndrome and the heart: cardiovascular complications and treatment strategies

Turner syndrome is a condition usually associated with reduced final height, gonadal dysgenesis, and thus insufficient circulating levels of female sex steroids, and infertility. A number of other signs and symptoms are seen more frequently with the syndrome. With respect to cardiac function, congenital malformations of the heart and the great vessels, hypertension and ischemic heart disease, and increased risk of aortic dissection are all conditions that the pediatrician or the physician caring for females with Turner syndrome should keep in mind. Many girls and adolescents with Turner syndrome receive growth hormone (GH) treatment, which has so far been an effective and well-tolerated therapy. Nevertheless, because of the experience from acromegaly, the physician should monitor blood pressure and perform echocardiography, together with clinical examinations by a cardiologist at regular intervals. During adulthood most women with Turner syndrome are faced with premature menopause and the need for female hormone replacement therapy (HRT). During clinical evaluation of girls and women with Turner syndrome, these conditions and complications should be kept under surveillance. Here the cardiovascular complications of Turner syndrome are reviewed. The risk of congenital heart defects such as bicuspid aortic valves, aortic coarctation, other valve abnormalities, and septal defect is increased. Likewise, the risk of aortic dissection at a young age is increased, as is the risk of hypertension, ischemic heart disease, and stroke. GH therapy does not seem to adversely affect the heart, although longer-term follow-up studies are needed. In short-term studies, HRT lowers blood pressure, while any effect on the risk of ischemic heart disease has not been evaluated. Treatment with GH and HRT are discussed in relation to the heart and great vessels. Presently, the pathophysiology of the congenital cardiovascular malformation in Turner syndrome is unexplained, although different theories exist. Recommendations for clinical practice are given, including life-long surveillance of cardiac function, aortic diameter and blood pressure.