Ethnic differences in the occurrence of the M1(ala213) haplotype of alpha-1-antitrypsin in asthmatic and non-asthmatic black and white South Africans.

An ethnic study of 175 individuals, comprising 65 black and 110 white South Africans, has shown a conclusive difference in the frequency of the M1(ala213) haplotype of alpha 1-antitrypsin (P < 0.00001). The M1(ala213) haplotype occurred more frequently in the black group. In the latter group, the frequency of the M1(ala213) haplotype was the same in both controls (0.55) and asthmatics (0.53). However, there was a significant difference in the frequencies (0.19 and 0.36) for the respective white groups (P < 0.01), the frequency of the M1(ala213) haplotype being much higher in the asthmatics. Apart from the above differences, there was also a difference in the elastase-inhibitory capacities of the homozygote phenotypes M1(val213) vs M1(ala213) (P < 0.0001), this capacity being lower in the latter phenotype. We conclude that the occurrence of the M1(ala213) allele of alpha 1-antitrypsin differs in various ethnic groups and may play a role in asthma.