Differences in the prevalence of a TaqI RFLP in the 3' flanking region of the alpha(1)-proteinase inhibitor gene between asthmatic and non-asthmatic black and white South Africans

The prevalence of the Taq I(-) allele in variants of alpha(1)-proteinase inhibitor (alpha(1)PI) was investigated in a group of 28 black asthmatic patients and 32 black control individuals, and was compared to 43 white asthmatic patients and 32 white control individuals. The plasma concentration of alpha(1)PI was determined in eight black and 14 white asthmatics without the Taq I(-) allele, and compared to seven black and three white asthmatics with the Taq I(-) allele. Alpha-1-PI concentration was also determined in 10 black and 29 white control individuals without the Taq I(-) allele and compared to seven black and three white controls with the Taq I(-) allele. There was a highly significant difference in the frequency of the Taq I(-) allele between black South Africans (24.1%) and white South Africans (6%) (p<0.00001) and a significant difference in the frequency of the Taq I(-) allele between black asthmatics and white asthmatics (p= 0.0004) and between black controls and white controls (p=0.011). The Taq I(-) allele was significantly associated with the M1(Val(213)) variant as compared to the M1(Ala(213)) of alpha(1)PI (p=0.0042). There was no difference in the concentration of alpha(1)PI between the asthmatics (black and white) lacking the Taq I(-) allele and the asthmatics (black and white) with the allele. However, a significant increase in plasma alpha(1)PI concentration was found in the asthmatics compared to the controls (p=0.011). The Taq I(-) allele did not seem to interfere with the basal expression of alpha(1)PI in the groups of asthmatic patients in this study.