Genome-wide scan of Graves' disease: Evidence for linkage on chromosome 5q31 in Chinese Han pedigrees

Graves' disease (GD), which is a common organ-specific autoimmune disorder, is multifactorial and develops in genetically susceptible individuals. Despite many studies of candidate genes, only associations with human leukocyte antigen and cytotoxic T lymphocyte antigen 4 have been generally detected, and the number of susceptibility genes remains unknown. To identify chromosomal regions contributing to GD, we conducted a genome-wide scan on 322 individuals from 54 Chinese Han multiplex GD pedigrees. Parametric linkage analysis revealed the strongest evidence for linkage at D5S436 on chromosome 5q31, with a maximum two-point LOD score of 2.8 and a maximum multipoint LOD score of 2.3. To further assess the significance of this suggestive finding, we typed four additional markers around D5S436 in this chromosome region, and a maximum two-point LOD score of 4.31 and a maximum multipoint LOD score of 4.12 were obtained for marker D5S2090 (with heterogeneity, α̂ = 0.38). Nonparametric multipoint analysis also showed significant excess allele sharing, with a P value as low as 0.001, at the same locus. Our findings provide evidence for a susceptibility locus for GD on chromosome 5q31 and support the existence of genetic heterogeneity in GD.