The common insertional polymorphism in the APOC1 promoter is associated with serum apolipoprotein C-I levels in Hispanic children

We examined the effect of APOC1-317insCGTT allele status ( HpaI RFLP, deletion [H1] and insertion [H2] alleles) on serum apolipoprotein (apo) C-I level in 362 Hispanic children in the Columbia University BioMarkers Study. The H2 allele was present in 147 subjects (40.6%). Serum apoC-I was 20% lower in the presence of the H2 allele in APOE ɛ3/ɛ3 homozygotes ( P = 0.003) but did not differ by H2 status in ɛ4 carriers. Insufficient numbers of ɛ2 carriers ( N = 45) were present for analysis. In multivariate analysis in the ɛ3/ɛ3 context, after adjusting for potential covariate effects and familial aggregation, the mean effect of H2/* versus H1/H1 on apoC-I level, was estimated to be 2.15 ± 0.55 mg/dl ( P < 0.0025). Plasma triglyceride level was weakly correlated with serum apoC-I level (Pearson's r = 0.17, P < 0.001) but was highly correlated with serum apoC-III (Pearson's r = 0.74, P < 0.0001). Nevertheless, presence of the H2 allele was not significantly associated with serum apoC-III level. Thus, the effect of APOC1 genotype on serum apoC-I level was not due to apoC-I level serving as a surrogate for triglyceride level. The APOC1-317insCGTT allele is a commonly polymorphic genetic marker that is associated with serum apoC-I level in the APOE ɛ3/ɛ3 context. These findings suggest that the mechanism of the previously described association with plasma TG is, at least in part, related to the correlation of the polymorphism with the level of expression of apoC-I.