Identification of a novel mutation for phytosterolemia. Genetic analyses of 2 cases.

Background: Phytosterolemia is one of the genetic disorders causing hypercholesterolemia and atherosclerosis together with the accumulation of plant sterol in plasma and tissues. The mutations in ABCG5 and ABCG8 genes, encoding sterolin-1 and -2, respectively, are responsible for phytosterolemia.

Methods: We performed genetic analyses on 2 Japanese phytosterolemia patients.

Results: We identified 2 mutations in the ABCG5 gene in these patients. The first patient was homozygous for a novel mutation, which was a 19-base pair tandem repeat insertion in exon 7, leading to a premature termination at codon 288. The second patient was a compound heterozygote; one of the mutations was the same as that found in the first patient, while the other mutation was a C to T substitution in exon 10, resulting in a premature termination at codon 446 (R446X). No other mutation was found in the ABCG5 and ABCG8 genes.

Conclusions: This result was concordant with previous observations that found most Asian phytosterolemia patients possessed mutations in the ABCG5 gene, and the site of the novel mutation was completely different from these previous reports, necessitating the extensive analyses for phytosterolemia.