A balanced chromosomal translocation involving chromosomes 3 and 16 in a patient with Mayer-Rokitansky-Kuster-Hauser syndrome reveals new candidate genes at 3p22.3 and 16p13.3

Background: Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome, or the congenital absence of uterus and vagina, is the most severe anomaly of the female reproductive tract. It affects 1 in 5,000 females, and is the second most common cause of primary amenorrhea. The etiology remains unknown in most patients, although four single gene defects and some repetitive copy number variants (CNVs) have been identified. Translocations in MRKH patients are very rare, and reported only in three patients previously without breakpoint mapping. We have identified the fourth MRKH translocation patient and are the first to characterize the breakpoints mapped by molecular methods. Results: The proband is a 17-year old white female with agenesis of the uterus and vagina who had a peripheral blood karyotype revealing a de novo balanced translocation 46,XX,t(3;16)(p22.3;p13.3)dn. There were no known related anomalies present in the proband or her family. No CNVs were found by chromosomal microarray analysis, and no genes were directly disrupted by the translocation. DNA sequencing of six nearby candidate genes-TRIM71, CNOT10, ZNF200, OR1F1, ZNF205, and ZNF213-did not reveal any mutations. RT-qPCR of proband lymphoblast RNA for 20 genes near the breakpoints of 3p22.3 and 16p13.3 showed significantly altered expression levels for four genes in the proband compared to three white female controls, after correction for multiple comparisons. Reduced expression was seen for CMTM7 and CCR4 on 3p22.3, while increased expression was observed for IL32 and MEFV on 16p13.3. Conclusion: We have mapped the breakpoints of our t( 3; 16)( p22.3; p13.3) translocation patient using molecular methods to within 13.6 kb at 3p22.3 and within 1.9 kb for 16p13.3 and have suggested 10 nearby genes that become plausible candidate genes for future study.