Functional effects of SNPs on metabolic enzymes and phenotypic outcomes

Abstract

Consider the MTHFR C677T polymorphism a single nucleotide change that reduces enzyme activity by 70% and affects folate metabolism in one-third of certain populations. This research characterized functional effects of five clinically significant SNPs on metabolic enzymes: MTHFR rs1801133, GSTP1 rs1695, COMT rs4680, DRD2 rs1800497, and CYP2C9 rs1799853. Enzyme activities were measured in liver microsomes and lymphocyte preparations from 150 genotyped individuals representing diverse Kenyan ethnic groups. Results confirmed substantial activity reductions for MTHFR (37.6% of wild-type), CYP2C9 (43.5%), and DRD2 (71.8%) variant alleles, while GSTP1 showed moderate reduction (78.3%) and COMT paradoxically showed 45.2% increased activity. Phenotypic associations were evaluated through metabolic challenge tests and clinical biomarkers. Homozygous MTHFR variant carriers showed 2.3-fold elevated homocysteine concentrations. These findings establish population-specific activity benchmarks for East African populations and identify individuals potentially requiring personalized therapeutic approaches.