Genotype Frequency of a 32-bp Deletion Mutation in the CCR5 Gene In Various Ethnic Groups

            DNA polymorphisms in chemokine receptor genes have been correlated to resistance to HIV-1 infection and to slower progression to AIDS.  In particular, a 32-bp deletion mutation in the b-chemokine receptor CCR5 gene has been associated with relative resistance to HIV-1 infection.  That is, individuals who are homozygous for this deletion mutation (∆32/∆32) appear to resist HIV-1 infection despite high-risk exposure, whereas those who are heterozygous (∆32/CCR5) appear to have slower progression to AIDS following infection.  To further elucidate the population genetics of this deletion mutation, we have tested nearly 1,900 DNA samples from various ethnic groups, using an oligonucleotide primer pair designed to discriminate CCR5 alleles without restriction endonuclease analysis.  The comparative genotype frequency of CCR5 heterozygosity (∆32/CCR5) was 61/363 (16.8%) in Caucasians, 16/303 (5.3%) in Hispanics from Puerto Rico, 9/592 (1.5%) in Pacific Islanders, 0/615 (0%) in Asians, and 0/20 (0%) in others (including Native Americans Indians and African Americans) (Table 2).  Low-level heterozygosity (∆32/CCR5) among Hispanics and Pacific Islanders (primarily part-Hawaiians) can be attributed to admixture with Caucasian genes.

Gonzalez, S., Tirado, G., Revuelta, G., Yamamura, Y., Lu, Y., Nerurkar, V.R., and Yanagihara, R.:  CCR5 chemokine receptor genotype frequencies among Puerto Rican HIV-1-seropositive individuals.  Bol. Asoc. Med P R  1998;90:12-15.

Lu, Y., Nerurkar, V.R., Dashwood, W-M., Woodward, C.L., Ablan, S., Shikuma, C.M., Grandinetti, A., Chang, H., Nguyen, H.T., Wu, Z., Yamamura, Y., Boto, W.O., Merriwether, A., Kurata, T., Detels, R., and Yanagihara, R.:  Genotype and allele frequency of a 32-base pair deletion mutation in the CCR5 gene in various ethnic groups:  absence of mutation among Asians and Pacific Islanders.  International Journal of Infectious Diseases (in press).

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