A single SNP is not sufficient to capture genetic diversity of the AMHR2 gene in an IVF population

Abstract

OBJECTIVE: Initial investigations of the anti-mullerian hormone receptor type 2 (AMHR2) suggested that one polymorphism was correlated with ovarian response. A larger, systematic study of that polymorphism (N = 1400) was unable to establish an association with decreased ovarian responsiveness or reserve. Given the critical role of AMH in ovarian physiology, further evaluation was merited. This study seeks to determine if other polymorphisms of AMHR2 are present and associated with altered phenotype (response or reserve). DESIGN: Prospective MATERIALS AND METHODS: 96 patients (mean age 37 years) who previously demonstrated poor ovarian responsiveness (<4 mature follicles on day of hCG) were studied. DNA was sequenced for the entire coding region of the AMHR2 gene including 90% of non-coding sequence and 1 kb of the promoter region (Applied Biosystems Variant Sequencing). This sequence was screened for novel and known bi-allelic SNPs. Polymorphisms were tested under linkage disequilibrium analysis to define markers representing total sequence variation and haplotype blocks in this population. Newly identified tagging SNPs were then evaluated by TaqMan genotyping in 96 age matched normal responders (>6 antral follicles, 6-13 oocytes retrieved). RESULTS: Sequence analysis identified 5 tagging SNPs captured all AMHR2 haplotypes effectively (dbSNP IDs; rs2002555, rs2272002, rs2071558, rs3741664, rs11170555). Subsequent haplotyping of a case/control population identified a diverse haplotype distribution in both populations. Unique haplotypes were only identified in the poor responder group at a small percentage (3.2%), suggesting that a larger population is needed to fully validate their significance. CONCLUSIONS: Evaluation of genetic heterogeneity of AMHR2 requires characterization of at least 5 tagging SNPs. Initial evaluation suggests a specific haplotype may increase the probability of poor ovarian responsiveness. Larger studies evaluating this relationship with ovarian responsiveness and reserve are ongoing.