Family-based analysis of candidate genes for polycystic ovary syndrome

Abstract

Context: Polycystic ovary syndrome (PCOS) is a complex disorder having both genetic and environmental components. A number of association studies based on candidate genes have reported significant association, but few have been replicated. D19S884, a polymorphic marker in fibrillin 3 (FBN3), is one of the few association findings that has been replicated in independent sets of families.

Objective: The aims of the study are: 1) to genotype single nucleotide polymorphisms (SNPs) in the region of D19S884; and 2) to follow up with an independent data set, published results reporting evidence for PCOS candidate gene associations.

Design: The transmission disequilibrium test (TDT) was used to analyze linkage and association between PCOS and SNPs in candidate genes previously reported by us and by others as significantly associated with PCOS.

Setting: The study was conducted at academic medical centers.

Patients or other participants: A total of 453 families having a proband with PCOS participated in the study. Sisters with PCOS were also included. There was a total of 502 probands and sisters with PCOS.

Intervention(s): There were no interventions.

Main outcome measure(s): The outcome measure was transmission frequency of SNP alleles.

Results: We identified a six-SNP haplotype block spanning a 6.7-kb region on chromosome 19p13.2 that includes D19S884. SNP haplotype allele-C alone and in combination with D19S884-allele 8 is significantly associated with PCOS: haplotype-C TDT chi(2) = 10.0 (P = 0.0016) and haplotype-C/A8 TDT chi(2) = 7.6 (P = 0.006). SNPs in four of the other 26 putative candidate genes that were tested using the TDT were nominally significant (ACVR2A, POMC, FEM1B, and SGTA). One SNP in POMC (rs12473543, chi(2) = 9.1; P(corrected) = 0.042) is significant after correction for multiple testing.

Conclusions: A polymorphic variant, D19S884, in FBN3 is associated with risk of PCOS. POMC is also a candidate gene of interest.

Figure 1

TDT and haplotype analysis of SNPs in the region of D19S884. A, Individual TDT results are shown for six SNPs and D19S884 located between exons 55 and 59 of FBN3 (number above each bar represents transmission frequency, and dashed line represents nominally significant χ² = 3.84). Also shown are the positions of the markers relative to the exons. B, Pairwise LD plot showing D′ values (percent) in the PCOS families. For construction of haplotypes in Haploview, D19S884 was coded as a two-allele system: allele 8 or not-8. (The x-axis displays location of chromosome 19: 8049164-8056141.)