COMT and Parkinson disease: COMT gene rs4633 polymorphism is associated with susceptibility to PD [25]. rs4633 polymorphism participates in variable pain-sensitive haplotype (LPS, APS, and HPS). rs4633 showed allele C in LPS and HPS haplotypes, while it showed allele T in APS haplotype. COMT gene polymorphisms may be inherited through an autosomal dominant or recessive trait.