TBX6, LHX1 and copy number variations in the complex genetics of Müllerian aplasia

BACKGROUND: Müllerian aplasia (MA) is a congenital disorder of the female reproductive tract with absence of uterus and vagina with paramount impact on a woman’s life. Despite intense research, no major genes have been found to explain the complex genetic etiology. METHODS AND RESULTS: We have used several genetic methods to study 112 patients with MA. aCGH identified CNVs in 8/50 patients (16%), including 16p11.2 and 17q12 deletions previously associated with MA. Subsequently, another four patients were shown to carry the ~0.53 Mb deletion in 16p11.2. More importantly, sequencing of TBX6, residing within 16p11.2, revealed two patients carrying a splice site mutation. Two previously reported TBX6 variants in exon 4 and 6 were shown to have a significantly higher frequency in patients (8% and 5%, respectively) than in controls (2% each). We also sequenced LHX1 and found three apparently pathogenic missense variants in 5/112 patients. Altogether, we identified either CNVs or variations in TBX6 or LHX1 in 30/112 (26.8%) MA patients. CNVs were found in 12/112 (10.7%), patients, novel variants in TBX6 or LHX1 in 7/112 (6.3%), and rare variants in TBX6 in 15/112 (13.4%) patients. Furthermore, four of our patients (4/112, 3.6%) were shown to carry variants in both TBX6 and LHX1 or a CNV in combination with TBX6 variants lending support to the complex genetic etiology of MA. CONCLUSIONS: We have identified TBX6 as a new gene associated with MA. Our results also support the relevance of LHX1 and CNVs in the development of this congenital malformation.