7665 Genome Sequencing of Patients and Their Families to Capture the Complete Genomic Landscape in MRKH

Abstract Disclosure: A. Navitski: None. L.P. Chorich: None. Z. Hawkins: None. J. Theisen: None. L.C. Layman: None. Background: Mayer–Rokitansky–Küster–Hauser (MRKH) syndrome is a rare congenital disorder, characterized by the absence/underdevelopment of the uterus and vagina. It may be associated with cardiac, renal, skeletal, and/or auditory defects. Evidence suggests genetic factors in some persons with MRKH (e.g., pathogenic variants in HNF1B, WNT4, and ZNHIT3). Additional genes essential for Müllerian and Wolffian duct development may play a key role in MRKH etiology. Compared to exome sequencing, genome sequencing (GS) provides a broader genomic coverage. This study aimed to use GS of well-characterized families with MRKH to detect clinically relevant pathogenic variants and to determine inheritance. Methods: GS was performed on 31 unrelated individuals with MRKH: type 1 (n=7); type 2 (n=20); unspecified (n=4) and their direct family members (n=93). The average depth was 36.7X. Variants were filtered by mapping quality >30, allelic frequency < 0.01 in gnomAD and 1000 genome databases, top consequence (frameshift, splice acceptor, splice donor, start-lost, stop-gain, stop-lost, transcript ablation), and a Combined Annotation-Dependent Depletion (CADD) score ≥ 20, which predicts high likelihood of deleterious functional consequences. Varsome, which contains >145 databases, was used to categorize variants. Variants were filtered by potential involvement in Mullerian, renal, skeletal, auditory, or cardiac development and function. Likely deleterious variants were confirmed by Sanger sequencing. Results: Of 31 probands, 7 had de novo coding heterozygous variants of uncertain significance (VUS) in: GLS, SF3B1, IPO11-LRRC70, TCP1, NR6A1, SIRT1, SUPT6H, and 10 probands had inherited coding heterozygous VUS, likely pathogenic, or pathogenic variants in ITIH5, AKR1A1, NPHP3, PDGFRA, TENT2, LY6L, RECQL4, TPRN, RESF1, C16orf95, with none of the carrier family members being affected. Five de novo non-coding and 9 inherited non-coding heterozygous VUS with a regulatory function were also detected. Two variants were predicted to be likely deleterious in MRKH. One patient and her healthy mother had a splice-donor variant in HOXA11-AS-205, encoding a long non-coding RNA. Another person and her healthy father had a stop-gain variant in ITIH5. Both variants were confirmed with Sanger sequencing. Conclusion: This comprehensive genetic analysis by GS in 31 well-characterized MRKH families revealed no clear pathogenic variants in the genes with known association to the MRKH phenotype. Two probands had likely deleterious variants in HOXA11-AS-205 and ITIH5 inherited from one parent, suggesting an autosomal dominant inheritance with reduced penetrance, variable expressivity, and/or a sex-limited phenotype to females. More comprehensive analysis of variants in non-coding regulatory regions may provide novel insights to better understand the complex genetic landscape of MRKH. Presentation: 6/2/2024