Genetic Etiology Of Oblique Vaginal Septum Syndrome

BackgroundHerlyn-Werner-Wunderlich syndrome(HWWS)is a rare congenital malformation of female urogenital tract,characterized by uterine didelphys,obstructed hemivagina and ipsilateral renal anomalies.However,due to limited number of cases and lack of large pedigrees,it is very difficult to explore the genetic etiology of HWWS.Only a few studies have been carried out and no positive conclusions can be drawn.To date,no candidate causative genes have been investigated,the genotype/phenotype associations and the inheritance pattern haven't been established.MethodsThis study collected a total of 20 trio families(proband and her biological parents)of patients diagnosed with HWWS.After informed consents,the clinical data including results of ultrasonography of pelvis and urinary system,spinal X-rays,and complete laboratory examinations were collected.In addition,trio families' blood samples were collected for whole genome sequencing and following bioinformatic data analysis.The candidate gene discovered in the HWWS patients was also screened in the established cohort of female Mullerian duct malformations for replication.All protein truncating variants and novel predicted damaging missense variants were validated by Sanger sequencing.Then,the immunohistochemical staining were used to explore the protein expression of the candidate gene in mesonephric/paramesonephric ducts of mouse embryos.ResultsAmong the 20 trio families enrolled,the data of 19 cases were valid and entered the bioinformatic analysis.We identified 1 denovo protein truncating variant in AKAP13 gene in a HWWS patient:c.3688₃689delCT(p.Leu1230ThrfsTerl3).We also identified 1 in-frame mutation,3 novel damaging missense variants:c.2326G>T(p.Asp776Tyr),c.5387C>G(p.Ser1796Cys),c.6598C>T(p.Arg2200Cys),and 2 low frequency damaging missense variants:c.124C>T(p.Arg42Cys),c.488C>T(p.Pro163Leu)in female Mullerian duct malformation cohort.All the variants mentioned above were validated by Sanger sequencing.Moreover,immunohistochemical staining of female mouse E13.5 and E14.5 embryos indicated that AKAP 13 was expressed in epithelium and mesenchyme of mesonephric/paramesonephric ducts.ConclusionsThrough the whole genome sequencing and mutation analysis,AKAP13 is the possible causative gene of HWWS and other female genital tract malformations.