Variants of CD36 gene and their association with CD36 protein expression in platelets.

BACKGROUND

The relationship between CD36 expression level in platelets and polymorphism of the CD36 gene still needs to be explored. Here, we investigated polymorphisms of the CD36 gene and CD36 expression level in platelets in the Chinese Han population.

MATERIALS AND METHODS

A total of 477 samples were sequenced for exons 2 to 14 of the CD36 gene using a polymerase chain reaction sequence-based typing method. In 192 of these individuals the expression levels of CD36 antigen were analysed by flow cytometry. The genotype-phenotype relationship in platelets was analysed.

RESULTS

A total of 22 variants of the CD36 gene were identified, of which five variants (111 A>T, 681 C>A, 1172-1183 del12b, 1236 delT and 1395 A>C) were novel variations, and nine were also found in single nucleotide polymorphism database (dbSNP) but had not been confirmed in individuals with CD36 deficiency. Two variants (329-332 delAC and 1228-1239 del12bp) in the coding region are the most frequent mutations in the Chinese population. Type II CD36 deficiency was identified in seven of 192 individuals, giving a frequency of 3.6%. Individuals with CD36 variations or wild-type genotypes both showed CD36 antigen negative, low-level and high-level expression patterns in platelets. The frequency of the nt-132 A>C polymorphism in the 5'-UTR is relatively high in the Chinese population (0.3516): the expression of CD36 was lower in individuals with nt-132 A>C than in those with the wild-type genotype.

DISCUSSION

The distribution of CD36 gene variants in the Chinese population is different from that previously reported. The levels of expression of CD36 antigen in platelets are not determined directly by the genotypes of the CD36 coding region. This suggests that the molecular basis of type II CD36 deficiency may be derived from combined effects of coding region and potential cis-regulatory elements in the 5'-UTR of the CD36 gene.