Candidate gene mapping studies in Turkish patients with Mullerian aplasia

Müllerian Aplasia, in other words Mayer-Rokitansky-Kuster-Hauser Syndrome or Congenital Absence of Uterus and Vagina (CAUV; OMIM 277000) is characterised by congenital agenesis of uterus, cervix and upper two-thirds of the vagina which is the second most common cause of primary amenorrhea. Müllerian aplasia is classified in two groups; type 1 is isolated form, type 2 is syndromic form accompanied by renal, cardiac, skeletal and hearing anomalies. The incidence of the disease is determined as 1/4500. Candidate gene analysis studies are still insufficient to reveal genetic etiology of Müllerian aplasia which is thought to be polygenic and multifactorial. Detection of copy number variations (CNVs) including genomic microduplications and microdeletions is extremely important in terms of determining new candidate genes related to the disease. In our study, 66 patients who were diagnosed with Müllerian aplasia were included. There is no chromosomal abnormality which may contribute to the disease. Genomic DNA of 19 patients were screened for revealing CNVs by Affymetrix Cytoscan HD microarray platform. Microduplications at 1p31.1, 13p14.11 and microdeletions at 16p11.2, 16p13.3, Xq25 were detected in four patients who were diagnosed with type 1 Müllerian aplasia. Homozygosity analysis was performed to reveal genomic regions that have susceptibility for recessive variations. But, there is no common region detected. Wingless-type MMTV integration site family, member 4 (WNT4, NM_ 030761.4) is the only well-characterized causative gene for Müllerian aplasia. Sequence analysis of exonic and intronic regions close to exon boundaries of WNT4 and possible candidate genes (total number of 12 genes) was performed. Variations of c.545-49_50insTGTC (n=5) in the intron 2, c.1535+47_48insC (n=5) in the intron 8 of the Hepatocyte Nuclear Factor 1 beta (HNF1B, NM_000458.3) gene and c.1162G>T (p.Ala388Ser) (n=5) in the exon 5 of the LIM Homeobox 1 (LHX1, NM_005568.4) gene were detected. Familial transmission of the detected variations has been found by screening the family members. In addition, effect of the p.Ala388Ser variation in the LHX1 gene on protein function was predicted "tolerable" by SIFT analysis. c.2117A>G (p.Lys706Arg) (n=1) and c.1732+13C>T (n=1) variations were detected respectively in the Family with Sequence Similarity 190, Member A (FAM190A/KIAA1680, NM_001145065.1) and Catenin Alpha 3 (CTNNA3, NM_013266) genes also, but these variations need to be confirmed. Our study on identification the gene or genes related to the Müllerian aplasia is still going on. Performing CNV analysis, homozygosity mapping and sequence analysis of possible candidate genes in a larger group of individuals with Müllerian aplasia is important for the elucidation of the molecular basis of the disease. Final data may help in the diagnosis and treatment of congenital female reproductive system anomalies.