A novel mutation in the anti-müllerian hormone gene as cause of persistent müllerian duct syndrome

Genetics of agenesis/hypoplasia of the uterus and vagina: narrowing down the number of candidate genes for Mayer-Rokitansky-Küster-Hauser Syndrome

PURPOSE

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome consists of congenital absence of the uterus and vagina and is often associated with renal, skeletal, cardiac, and auditory defects. The genetic basis is largely unknown except for rare variants in several genes. Many candidate genes have been suggested by mouse models and human studies. The purpose of this study was to narrow down the number of candidate genes.

METHODS

Whole exome sequencing was performed on 111 unrelated individuals with MRKH; variant analysis focused on 72 genes suggested by mouse models, human studies of physiological candidates, or located near translocation breakpoints in t(3;16). Candidate variants (CV) predicted to be deleterious were confirmed by Sanger sequencing.

RESULTS

Sanger sequencing verified 54 heterozygous CV from genes identified through mouse (13 CV in 6 genes), human (22 CV in seven genes), and translocation breakpoint (19 CV in 11 genes) studies. Twelve patients had ≥ 2 CVs, including four patients with two variants in the same gene. One likely digenic combination of LAMC1 and MMP14 was identified.

CONCLUSION

We narrowed 72 candidate genes to 10 genes that appear more likely implicated. These candidate genes will require further investigation to elucidate their role in the development of MRKH.

Translating genomics to the clinical diagnosis of disorders/differences of sex development

The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the complexity of conditions grouped under DSD, genome-wide scanning methods are better suited for identifying disease causing gene variant(s) and providing a clinical diagnosis. Here, we review a number of established genomic tools (karyotyping, chromosomal microarrays and exome sequencing) used in clinic for DSD diagnosis, as well as emerging genomic technologies such as whole-genome (short-read) sequencing, long-read sequencing, and optical mapping used for novel DSD gene discovery. These, together with gene expression and epigenetic studies can potentiate the clinical diagnosis of DSD diagnostic rates and enhance the outcomes for patients and families.

Prostatic adenocarcinoma in the setting of persistent müllerian duct syndrome: a case report

Persistent müllerian duct syndrome (PMDS) is a form of disordered sex development in which rudimentary müllerian structures are identified in phenotypically and genotypically normal males. It is caused by defects in the anti-müllerian hormone (AMH) system. Since patients with PMDS present with undescended testes, testosterone production by Leydig cells later in life is often decreased. The role of androgens in prostate cancerogenesis is well known. Cryptorchid testes and diminished testosterone levels in post-pubertal life in patients with PMDS play a protective role against prostate cancer, and hence, prostate cancer is a rare event in patients with PMDS. Herein, we present a patient who underwent prostatectomy for high-grade prostatic adenocarcinoma with persistent müllerian structures (such as rudimentary uterus, fallopian tubes, and cervix) identified during surgery. To our knowledge, this is the second case reported in the English language literature where PMDS was associated with prostate cancer.

Anti-müllerian hormone: a valuable addition to the toolbox of the pediatric endocrinologist

Anti-Müllerian hormone (AMH), secreted by immature Sertoli cells, provokes the regression of male fetal Müllerian ducts. FSH stimulates AMH production; during puberty, AMH is downregulated by intratesticular testosterone and meiotic germ cells. In boys, AMH determination is useful in the clinical setting. Serum AMH, which is low in infants with congenital central hypogonadism, increases with FSH treatment. AMH is also low in patients with primary hypogonadism, for instance in Down syndrome, from early postnatal life and in Klinefelter syndrome from midpuberty. In boys with nonpalpable gonads, AMH determination, without the need for a stimulation test, is useful to distinguish between bilaterally abdominal gonads and anorchism. In patients with disorders of sex development (DSD), serum AMH determination helps as a first line test to orientate the etiologic diagnosis: low AMH is indicative of dysgenetic DSD whereas normal AMH is suggestive of androgen synthesis or action defects. Finally, in patients with persistent Müllerian duct syndrome (PMDS), undetectable serum AMH drives the genetic search to mutations in the AMH gene, whereas normal or high AMH is indicative of an end organ defect due to AMH receptor gene defects.

AMH gene mutations in two Egyptian families with persistent müllerian duct syndrome

The anti-müllerian hormone (AMH) is responsible for regression of müllerian ducts during male sexual differentiation. Mutations in the AMH gene or its type II receptor gene AMHR2 lead to persistence of the uterus and fallopian tubes in male children, i.e. persistent müllerian duct syndrome (PMDS). Both conditions are transmitted according to an autosomal recessive pattern and are symptomatic only in males. We report on 2 unrelated Egyptian consanguineous families with PMDS. The first family comprised 3 affected prepubertal sibs complaining of undescended testes. Pelvic exploration and laparotomy revealed müllerian duct derivatives. The other family was presenting with an adolescent male with impalpable left testis, and pelvic exploration showed remnants of fallopian tubes and rudimentary uterus. AMH levels were very low and almost undetectable in all affected patients in both families. Direct sequencing of the coding region of the AMH gene identified 2 homozygous mutations in exon 1, R95X in the first family and V12G in the second family. These data confirmed the autosomal recessive type of PMDS. Molecular investigation of this rare disorder in a larger number of cases with undescended testes in Egypt is warranted for proper diagnosis and genetic counseling.

Control of sex development

The process of sexual differentiation is central for reproduction of almost all metazoan, and therefore, for maintenance of practically all multicellular organisms. In sex development, we can distinguish two different processes, sex determination, that is the developmental decision that directs the undifferentiated embryo into a sexually dimorphic individual. In mammals, sex determination equals gonadal development. The second process known as sex differentiation takes place once the sex determination decision has been made through factors produced by the gonads that determine the development of the phenotypic sex. Most of the knowledge on the factors involved in sexual development came from animal models and from studies of cases in whom the genetic or the gonadal sex does not match the phenotypical sex, that is, patients affected by disorders of sex development (DSDs). Generally speaking, factors influencing sex determination are transcriptional regulators, whereas factors important for sex differentiation are secreted hormones and their receptors. This review focuses on these factors and whenever possible, references regarding the 'prismatic' clinical cases are given.

Persistent Mullerian duct syndrome caused by both a 27-bp deletion and a novel splice mutation in the MIS type II receptor gene

BACKGROUND

Persistent Mullerian duct syndrome (PMDS) is a rare form of male pseudohermaphroditism that is characterized by the persistence of Mullerian derivatives in otherwise normally virilized males. Mutations of the Mullerian inhibiting substance (MIS) gene or the MIS type II receptor (MISRII) gene have been identified in PMDS patients with autosomal recessive transmission. We analyzed a compound heterozygote PMDS patient who had a 27-bp deletion in exon 10 in one allele and a novel mutation in intron 5 in the other allele of the MISRII gene.

METHODS

Whole blood and tissue samples were obtained from a one-month-old 46,XY male with persistent PMDS and the MISRII gene was sequenced and compared to his mother's genomic DNA and that of 22 normal individuals. Serum MIS and the reproductive hormones were measured by standard immunoassays.

RESULTS

The patient's hormone levels were normal but the gene for MISRII contained several mutations, a 27-bp deletion in exon 10 on one allele (one of the most common mutations in PMDS) and a novel mutation in intron 5 in the other allele that altered splicing, resulting in retention of the intron and a frameshift, introducing a stop codon. Other mutations in introns 6 and 9 and in exon 11 might not be functionally significant.

CONCLUSIONS

This case reveals a novel mutation in the MISRII gene involving intronic sequences, which when coexisting with the already identified 27-bp deletion in exon 10, leads to PMDS.

Persistent müllerian duct syndrome and prostate cancer

A localized Gleason score 6 (3 + 3) prostate cancer was found in a 56-year-old man with bilateral cryptorchidism. Radical laparoscopic prostatectomy was performed. However, at the beginning of the procedure, a uterus, two fallopian tubes, and two intra-abdominal gonads were endoscopically identified. The müllerian rests were excised and the gonads biopsied. The histologic examination showed testicular tissue. The association of prostate cancer and persistent müllerian duct syndrome to our knowledge has not previously been reported. Prostate cancer is an androgen-dependent neoplasm, and patients with male pseudohermaphroditism have poor androgen production that should provide protection against it.