UGT1A1 and Huntington disease: Individuals homozygous for 7 repetitions (7/7) have higher serum bilirubinconcentrations than heterozygotes (7/6) or those with the wild type 6-repetitions(6/6).35,36 In HD patients, UGT1A1*28 polymorphismshowed a strong effect on bilirubin levels and genotype 7/7 appears to have asignificant effect on the reduction of cardiovascular events and death.37