Background: Isolated persistence of Müllerian ducts in an otherwise normally virilised 46,XY newborn, a condition known as PMDS, is a disorder of sex development (DSD) due to a defect limited to AMH-dependent Müllerian duct regression.
Objective and hypothesis: We report the case of a patient with PMDS and extremely low serum AMH in whom no mutations were detected in the AMH gene coding sequences. A single base deletion identified in the AMH promoter was hypothesized to underlie isolated AMH deficiency.
Method: Case report: a completely virilised newborn presented with nonpalpable gonads. Testosterone was high (358 ng/dl), AMH low (1.1 ng/ml), a uterus and Fallopian tubes were evidenced by USA, but CAH was ruled out owing to normal adrenal steroids and a 46,XY karyotype. PMDS due to AMH deficiency was suspected. DNA sequencing detected no mutations in the AMH gene coding sequences, but a homozygous single-base deletion (c.-225delA) was identified at a putative SF1 response element of the AMH promoter. To assess the effect of the c.-225delA variant, AMH promoter activity was analysed in luciferase assays, and the ability of SF1 binding to the −228 binding site in the AMH promoter was studied by EMSA.
Results: The single base deletion c.-225delA decreased AMH promoter activity by 58±14%, to a similar extent of what was observed when the −228 SF1 site was completely disrupted by in vitro directed mutagenesis (66±5%). In EMSA experiments, interaction between SF1 and its AMH −228 binding site was lost when the oligonucleotide carried c.-225delA or the fully disrupted SF1 site.
Conclusion: The single base deletion c.-225delA within the −228 SF1 site of the AMH promoter impairs SF1 binding to and transactivation of the AMH promoter, resulting in extremely decreased AMH production. This is the first description of an AMH promoter mutation leading to PMDS.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology