Comparison of insertion rate of L1 retroposon into intron 30 of the neurofibromatosis type 1 gene in seven Asian and Pacific populations.

The allele frequency of a L1 retroposon insertion into intron 30 of the neurofibromatosis type 1 (NF1) gene was determined by analyzing amplified fragment lengths in seven Asian or Pacific populations; namely, Japanese, Chinese, Indian, Malay, Filipino, Indonesian and New Guinean. Nearly 100 chromosomes from each group were analyzed. The presence of the L1 insertion was identified by the appearance of an abnormally large PCR-amplified product. The insertion frequency varied from 0.45 to 0.75, depending on the population group. Malay and Indonesia populations were found to have the highest insertion frequencies (0.75 and 0.72, respectively), while the wild-type genotype was more prevalent in Indians. The lowest insertion frequency (0.45), observed in Indians, was nearest to that reported in Westerners (0.35). The different L1 insertion frequencies found in Asian and Pacific groups reflect a major divergence in these human populations. Japanese and Chinese populations showed the highest heterozygosity (0.50), suggesting the usefulness of this polymorphism in linkage analysis in these populations. [ABSTRACT FROM AUTHOR]