Susanne Ledig

WNT10A Mutations Are a Frequent Cause of a Broad Spectrum of Ectodermal Dysplasias with Sex-Biased Manifestation Pattern in Heterozygotes

Odonto-onycho-dermal dysplasia (OODD), a rare autosomal-recessive inherited form of ectodermal dysplasia including severe oligodontia, nail dystrophy, palmoplantar hyperkeratosis, and hyperhidrosis, was recently shown to be caused by a homozygous nonsense WNT10A mutation in three consanguineous Lebanese families. Here, we report on 12 patients, from 11 unrelated families, with ectodermal dysplasia caused by five previously undescribed WNT10A mutations. In this study, we show that (1) WNT10A mutations cause not only OODD but also other forms of ectodermal dysplasia, reaching from apparently monosymptomatic severe oligodontia to Schöpf-Schulz-Passarge syndrome, which is so far considered a unique entity by the findings of numerous cysts along eyelid margins and the increased risk of benign and malignant skin tumors; (2) WNT10A mutations are a frequent cause of ectodermal dysplasia and were found in about 9% of an unselected patient cohort; (3) about half of the heterozygotes (53.8%) show a phenotype manifestation, including mainly tooth and nail anomalies, which was not reported before in OODD; and (4) heterozygotes show a sex-biased manifestation pattern, with a significantly higher proportion of tooth anomalies in males than in females, which may implicate gender-specific differences of WNT10A expression.

Recurrent aberrations identified by array-CGH in patients with Mayer-Rokitansky-Küster-Hauser syndrome

OBJECTIVE To identify genetic causes of Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome. DESIGN Prospective laboratory study. SETTING University hospital. PATIENT(S) Fifty-six patients with MRKH syndrome. INTERVENTION(S) Identification of microdeletions and -duplications in a group of 48 MRKH patients by array-CGH. Results obtained by array-CGH were confirmed by RT-qPCR. Sequential analysis of two candidate genes LHX1 and HNF1B in a group of 56 MRKH patients. MAIN OUTCOME MEASURE(S) Identification of chromosomal regions and genes (recurrent and private) associated with MRKH syndrome. RESULT(S) We could delineate three definitively relevant regions (1q21.1, 17q12, and 22q11.21) and suggest that LHX1 und HNF1B are candidate genes for MRKH syndrome, because we identified recurrent deletions affecting these genes and a possible causative missense mutation in LHX1. CONCLUSION(S) Our findings suggest that different chromosomal regions are associated with MRKH syndrome.

Partial deletion of DMRT1 causes 46,XY ovotesticular disorder of sexual development

OBJECTIVE Ovotesticular disorder of sexual development (DSD) is an unusual form of DSD, characterized by the coexistence of testicular and ovarian tissue in the same individual. In a subset of patients, ovotesticular DSD is caused by 46,XX/46,XY chimerism or mosaicism. To date, only a few monogenetic causes are known to be associated with XX and XY ovotesticular DSD. DESIGN AND METHODS Clinical, hormonal, and histopathological data, and results of high-resolution array-comparative genomic hybridization (CGH) were obtained from a female patient with 46,XY ovotesticular DSD with testicular tissue on one side and an ovary harboring germ cells on the other. Results obtained by array-CGH were confirmed by RT-quantitative PCR. RESULTS We detected a deletion of ∼35 kb affecting exons 3 and 4 of the DMRT1 gene in a female patient with 46,XY ovotesticular DSD. To the best of our knowledge, this is the smallest deletion affecting DMRT1 presented to this point in time. CONCLUSIONS We suggest that haploinsufficiency of DMRT1 is sufficient for both XY gonadal dysgenesis and XY ovotesticular DSD. Furthermore, array-CGH is a very useful tool in the molecular diagnosis of DSD.

Copy Number Variants in Premature Ovarian Failure and Ovarian Dysgenesis

Premature ovarian failure (POF) is a heterogeneous group of disorders with amenorrhea and high serum gonadotropins in women of less than 40 years. Ovarian dysgenesis (OD) which is characterised by the loss of follicles before puberty describes the most severe POF outcome. Although a multitude of different factors including non-genetic as well as genetic causes are known to play a role in the development of POF and OD, the underlying etiology remains unsolved in the majority of cases. In the last years, array-CGH was found to be a very useful tool in the identification of candidate genes in different conditions. Therefore, we performed array-CGH analysis by using high-resolution Agilent oligonucleotide arrays in a total of 74 POF and OD patients and identified 44 private losses and gains potentially causative for POF. It is striking to note that a lot of the genes involved in these rearrangements can be classified in (i) genes involved in meiosis (e.g. PLCB1, RB1CC1, MAP4K4), (ii) genes involved in DNA repair (e.g. RBBP8) and (iii) genes involved in folliculogenesis or male fertility in homologs of model organisms (e.g. IMMP2L, FER1L6, MEIG1).

Novel and Recurrent Mutations in Patients with Androgen Insensitivity Syndromes

Background/Aims: Androgen insensitivity syndrome (AIS) caused by mutations within the androgen receptor gene represents a variety of phenotypes from females with 46,XY karyotype over individuals with ambiguous genitalia to infertile males. Methods: We studied 24 patients with AIS by sequencing androgen receptor gene. 19 of the investigated patients were affected by complete androgen insensitivity syndrome (CAIS) and 5 suffered from partial androgen insensitivity syndrome (PAIS). Results: So far we have detected 12 unreported mutations as well as 9 recurrent mutations (3 recurrent mutations were detected twice) in exons 2–8 of the androgen receptor gene. Three of the novel mutations cause a frameshift with subsequent premature termination and were found in patients with CAIS. These frameshifts were induced by single nucleotide deletion or insertion, or in one case by a 13-bp deletion, respectively. Another premature stop codon found in a CAIS patient results from an already reported nucleotide substitution in exon 5. Furthermore, in a CAIS patient we found a novel duplication of codon 788. All other mutations caused single base substitutions spread through exons 2–8 and were associated with CAIS or PAIS. Conclusions: We report a broad spectrum of different mutations within the AR gene leading to various manifestations of AIS. Apart from truncating mutations, a reliable genotype/phenotype correlation cannot be established. Therefore, modifying factors must be effective.

Mutations in WNT9B are associated with Mayer-Rokitansky-Küster-Hauser syndrome.

Mayer–Rokitansky–Küster–Hauser syndrome (MRKHS) is a well‐known malformation pattern of the Müllerian ducts (MDs) characterized by congenital absence of the uterus and vagina. To date, most cases remain unexplained at molecular level. As female Wnt9b‐/‐ mice show a MRKHS‐like phenotype, WNT9B has emerged as a promising candidate gene for this disease. We performed retrospective sequence analyses of WNT9B in 226 female patients with disorders of the MDs, including 109 patients with MRKHS, as well as in 135 controls. One nonsense mutation and five likely pathogenic missense mutations were detected in WNT9B. Five of these mutations were found in cases with MRKHS accounting for 4.6% of the patients with this phenotype. No pathogenic mutations were detected in the control group (p = 0.017). Interestingly, all of the MRKHS patients with a WNT9B mutation were classified as MRKHS type 1, representing 8.5% of the cases from this subgroup. In previous studies, two of the patients with a WNT9B mutation were found to carry either an additional deletion of LHX1 or a missense mutation in TBX6. We conclude that mutations in WNT9B were frequently associated with MRKHS in our cohort and some cases may be explained by a digenic disease model.

Prenatal diagnosis of Roberts syndrome and detection of an ESCO2 frameshift mutation in a Pakistani family

We report two siblings with Roberts syndrome (RBS), and an attempt to delineate the underlying molecular mechanism leading to familial recurrence.

Variations in RBM8A and TBX6 are associated with disorders of the müllerian ducts.

OBJECTIVE To identify genetic causes of malformations of the müllerian ducts. DESIGN Retrospective laboratory study. SETTING University hospital. PATIENT(S) A total of 167 patients with disorders of the müllerian ducts: 116 patients with Mayer-Rokitansky-Küster-Hauser syndrome and 51 patients with fusion disorders of the müllerian ducts. The control group was composed of 94 fertile women with at least one child. INTERVENTION(S) Sequential analysis of RBM8A and TBX6 in a group of 167 clinically well-defined patients with disorders of the müllerian ducts. MAIN OUTCOME MEASURE(S) Identification of rare variants in RBM8A and TBX6. RESULT(S) In total, we detected four RBM8A variants in 13 patients with disorders of the müllerian ducts and two heterozygous TBX6 variants in 5 of 167 patients. CONCLUSION(S) Mutations of RBM8A and TBX6 are associated with disorders of the müllerian ducts.

A Novel SRY Gene Mutation p.F109L in a 46,XY Female with Complete Gonadal Dysgenesis.

46,XY complete gonadal dysgenesis (CGD) is a disorder of sexual development that can result from different mutations in genes associated with sex determination. Patients are phenotypically females, and the disease is often diagnosed in late adolescence because of delayed puberty. Here, we present the clinical and molecular data of a 46,XY female CGD patient with gonadoblastoma with dysgerminoma and incidentally found inherited thrombophilia. The clinical significance of the described de novo SRY gene mutation c.325T>C (p.F109L) is discussed. This case report supports the critical role of the HGM domain in the SRY gene and the need of a multidisciplinary approach for CGD patients.

Premature ovarian failure caused by a heterozygous missense mutation in POF1B and a reciprocal translocation 46,X,t(X;3)(q21.1;q21.3).

In a patient affected by premature ovarian failure, a reciprocal translocation between chromosomes X and 3 and an additional heterozygous missense mutation in the X-linked gene POF1B were detected. Homozygosity for POF1B mutations is well-known to be associated with premature ovarian failure. In this case, the rare combination of skewed X inactivation due to the reciprocal translocation involving one X chromosome and heterozygosity for a known POF1B mutation explains the phenotype.