Genetic variants in RET and risk of Hirschsprung's disease in Southeastern Chinese: a haplotype-based analysis

BACKGROUND: Hirschsprung's disease (HSCR) is a classic oligogenic disorder. Except inactivating mutations of RET, some single nucleotide polymorphisms (SNPs) are identified to be associated with the risk of HSCR. This study was conducted to examine the impact of the haplotypes profile of the reported associated SNPs of RET on the risk of HSCR in a Southeastern Chinese population. METHODS: Genotypes of -5G > A (rs10900296), -1A > C (rs10900297), c135G > A (rs1800858), c1296A > G (rs1800860), and c2307T > G (rs1800861) were analyzed in 123 HSCR patients and 168 controls by polymerase chain reaction amplification and direct sequencing. Associations with risk of HSCR were estimated by odds ratio (OR) and their 95% confidence intervals (95% CI) using logistic regression. RESULTS: We observed a significantly increased risk of HSCR associated with the RET -5AA (OR = 17.75, 95% CI = 7.34-42.92), -1CC (OR = 10.89, 95% CI = 3.13-37.85), 135AA (OR = 13.61, 95% CI = 6.14-30.14), 1296GG (OR = 2.40, 95% CI = 1.38-4.18) or 2307GG (OR = 9.79, 95% CI = 4.28-22.43) respectively. The five SNPs were in strong linkage disequilibrium. The haplotype A-C-A-G-G (OR = 5.06, 95% CI = 1.97-12.99) and diplotype A-C-A-G-G/A-C-A-G-G (OR = 21.08, 95% CI = 5.28-84.09) was also associated with the increased risk of HSCR, indicating a cumulative effect of these SNPs on the susceptibility of HSCR. CONCLUSION: These results support the hypothesis that common variations in RET pathway might play an important role in development of HSCR.