Collagen Ialpha1 and vitamin D receptor gene polymorphisms in South African whites, blacks and Indians.

OBJECTIVE: To determine whether polymorphic differences exist between black, white and Indian South Africans in genes associated with bone mineral density and osteoporosis.
DESIGN: Genes selected were the vitamin D receptor (Apa I and Taq I polymorphisms) and collagen (Sp I transcription factor polymorphism) using standard molecular biology techniques.
SETTING: Department of Chemical Pathology, Nelson R Mandela School of Medicine, University of Natal, Durban, South Africa.
SUBJECTS: Healthy male and female blood donors living in the Durban metropolitan region, South Africa. The group comprised black Africans (n=264), white Caucasians (n=247) and Asians of Indian origin (n=194).
RESULTS: No significant differences in genotypes were seen between white and Indian subjects. Blacks had a significantly higher frequency of the TT Taq I genotype and a significantly lower frequency of the Ss Sp I genotype. No ss genotype was detected in blacks.
CONCLUSION: The very low frequency of the collagen Sp I s allele and higher frequency of the VDR T allele in blacks may be associated with the lower incidence of osteoporosis in this ethnic group.