A Novel Homozygous AMRH2 Gene Mutation in a Patient with Persistent Müllerian Duct Syndrome

Identification of AMH and AMHR2 Variants Led to the Diagnosis of Persistent Müllerian Duct Syndrome in Three Cases

Persistent Müllerian duct syndrome (PMDS) is a rare autosomal recessive disorder of sexual development in males, defined by the presence of Müllerian remnants with otherwise normal sexual differentiation. Mutations in anti-Müllerian hormone (AMH) and AMH receptor type 2 (AMHR2) genes are the main causes of PMDS. In this study, we performed molecular genetic analysis of 11 unrelated cryptorchidism patients using whole-exome sequencing and classified the variants. Three of the 11 patients had biallelic mutations in AMH or AMHR2. Case 1 carried a homozygous 4-bp deletion; c.321_324del:p.Q109Lfs*29 in exon 1 of AMH (NM_000479 transcript), which is a frameshift mutation, leading to the loss of function of AMH. Case 2 carried compound heterozygous mutations; c.494_502del (p.I165_A168delinsT) in exon 4 and g.6147C>A of AMHR2 (NM_001164690 transcript). Case 3 carried compound heterozygous mutations; c.G1168A (p.E390K) in exon 9 and c.A1315G (p.M439V) in exon 10 of AMHR2 (NM_001164690 transcript). All three patients were admitted due to azoospermia- and oligospermia-caused infertility. They were furtherly diagnosed with PMDS, as pelvic magnetic resonance imaging revealed the presence of Müllerian remnants. Our study suggests that PMDS and genetic analysis should be considered during the differential diagnosis of cryptorchidism.

Novel variant in HHAT as a cause of different sex development with partial gonadal dysgenesis associated with microcephaly, eye defects, and distal phalangeal hypoplasia of both thumbs: Case report

The palmitoylation of the Hedgehog (Hh) family of morphogens, named sonic hedgehog (SHH), desert hedgehog (DHH), and Indian hedgehog (IHH), is crucial for effective short- and long-range signaling. The hedgehog acyltransferase (HHAT) attaches the palmitate molecule to the Hh; therefore, variants in HHAT cause a broad spectrum of phenotypes. A missense HHAT novel variant c.1001T>A/p.(Met334Lys) was described in a patient first referred for a 46,XY different sexual development with partial gonadal dysgenesis but with microcephaly, eye defects, and distal phalangeal hypoplasia of both thumbs. The in silico analysis of the variant predicted an affectation of the nearest splicing site. Thus, in vitro minigene studies were carried out, which demonstrated that the variant does not affect the splicing. Subsequent protein in silico studies supported the pathogenicity of the variant, and, in conclusion, this was considered the cause of the patient's phenotype.

Identification of four novel variant in the AMHR2 gene in six unrelated Turkish families

PURPOSE

Persistent Müllerian duct syndrome (PMDS) is characterized by the persistence of Müllerian structures in male with normal phenotype. Most cases occur as a result of mutations in the anti-Müllerian hormone (AMH) or AMHR2 genes. In this study, we aim to discuss the results of clinical, laboratory, and molecular genetic analysis of cases detected to have AMHR2 gene mutation.

METHODS

A total of 11 cases from 6 families were included in the study. AMHR2 gene mutation analyses were performed by sequencing of the coding exons and the exon-intron boundaries of the genes. The American College of Medical Genetics guidelines were used for the classification of the detected variants.

RESULTS

Six of the 11 cases were admitted due to bilateral undescended testes and five cases due to inguinal hernia (three transverse testicular ectopia and two hernia uterus inguinalis). All cases had normal AMH levels. Seven different variants were identified in the six families. The variants detected in four cases were considered novel (c.78del, c.71G > A, c.1460dup, c.1319A > G). Two of the novel variants were missense (exon 2 and exon 10) mutations, one was deletion (exon 2), and one duplication (exon 11).

CONCLUSION

We identified four novel mutations in the AMHR2 gene resulting in PMDS. Duplication mutation (c.1460dup) in the AMHR2 gene causing PMDS was demonstrated for the first time. The most important complications of PMDS are infertility and malignancy. Early diagnosis is vital to preventing malignancy. Vas deferens and vascular structures may be injured during orchiopexy. Therefore, patients should always be referred to experienced clinics.

Persistent Müllerian duct syndrome due to anti-Müllerian hormone receptor 2 microdeletions: a diagnostic challenge

The persistent Müllerian duct syndrome (PMDS) is defined by the persistence of Müllerian derivatives in an otherwise normally virilized 46,XY male. It is usually caused by mutations in either the anti-Müllerian hormone (AMH) or AMH receptor type 2 (AMHR2) genes. We report the first cases of PMDS resulting from a microdeletion of the chromosomal region 12q13.13, the locus of the gene for AMHR2. One case involved a homozygous microdeletion of five exons of the AMHR2 gene. In the second case, the whole AMHR2 gene was deleted from the maternally inherited chromosome. The patient's paternal allele carried a stop mutation, which was initially thought to be homozygous by Sanger sequencing. Diagnostic methods are discussed, with an emphasis on comparative genomic hybridization and targeted massive parallel sequencing.

Molecular Basis of CYP19A1 Deficiency in a 46,XX Patient With R550W Mutation in POR: Expanding the PORD Phenotype

CONTEXT

Mutations in cytochrome P450 oxidoreductase (POR) cause a form of congenital adrenal hyperplasia (CAH). We report a novel R550W mutation in POR identified in a 46,XX patient with signs of aromatase deficiency.

OBJECTIVE

Analysis of aromatase deficiency from the R550W mutation in POR.

DESIGN, SETTING, AND PATIENT

Both the child and the mother had signs of virilization. Ultrasound revealed the presence of uterus and ovaries. No defects in CYP19A1 were found, but further analysis with a targeted Disorders of Sexual Development NGS panel (DSDSeq.V1, 111 genes) on a NextSeq (Illumina) platform in Madrid and Barcelona, Spain, revealed compound heterozygous mutations c.73_74delCT/p.L25FfsTer93 and c.1648C > T/p.R550W in POR. Wild-type and R550W POR were produced as recombinant proteins and tested with multiple cytochrome P450 enzymes at University Children's Hospital, Bern, Switzerland.

MAIN OUTCOME MEASURE AND RESULTS

POR-R550W showed 41% of the WT activity in cytochrome c and 7.7% activity for reduction of MTT. Assays of CYP19A1 showed a severe loss of activity, and CYP17A1 as well as CYP21A2 activities were also lost by more than 95%. Loss of CYP2C9, CYP2C19, and CYP3A4 activities was observed for the R550W-POR. Predicted adverse effect on aromatase activity as well as a reduction in binding of NADPH was confirmed.

CONCLUSIONS

Pathological effects due to POR-R550W were identified, expanding the knowledge of molecular pathways associated with aromatase deficiency. Screening of the POR gene may provide a diagnosis in CAH without defects in genes for steroid metabolizing enzymes.