Linkage of the apo CIII microsatellite with isolated low high-density lipoprotein cholesterol.

To evaluate whether a highly polymorphic microsatellite region within intron 3 of the apolipoprotein (apo) CIII gene is linked to the isolated low HDL-C phenotype, we studied eight unrelated probands (mean HDL-C = 10+/-5 mg/dl) and 157 biological family members. After PCR amplification of genomic DNA and denaturing polyacrylamide gel electrophoresis, 26 alleles were identified in this microsatellite including 9 alleles heretofore unreported. Quantitative sib-pair linkage analysis demonstrated strong evidence of linkage between the isolated low HDL-C phenotype and the apo CIII microsatellite region (P = 0.007). The microsatellite was also linked to apo AI (P = 0.001), the primary apolipoprotein of HDL-C. Therefore, this highly polymorphic microsatellite region is a potentially important marker in the genetic evaluation of the isolated low HDL-C phenotype.