The results suggested that, when the rs61730970, rs200798148 and rs146535482 alleles of the HH gene lacked particular single nucleotide polymorphisms (SNPs), the patients were associated with a greater risk of HSCR and/or ARM [HSCR: odds ratio (OR)=1.543, P=0.004; OR=1.494, P=0.007; rs146535482: OR=1.556, P=0.003, respectively.