Stevens G, Ramsay M, Jenkins T
Department of Human Genetics, School of Pathology, The South African Institute for Medical Research and University of the Witwatersrand, Johannesburg.
Hum Genet. 1997 Apr;99(4):523-7. doi: 10.1007/s004390050400.
Oculocutaneous albinism (OCA2) is the most common autosomal recessive disorder in the South African Negroid population, occurring with a prevalence of 1/3900 individuals. The OCA2 locus, P, has been mapped to chromosome 15q11-q13 and a 2.7-kb interstitial deletion has been found to be the common mutation in Africa. This study reports the detection of the deletion allele in OCA2-affected individuals from the southern African, Zambian and Central African Republic (CAR) Negroid populations (0.77, 131/170 OCA2 chromosomes; 0.79, 11/14; 0.33, 4/12, respectively). Normally pigmented individuals from different African countries were also tested. The deletion mutation was found at a frequency of 0.013 (10/780) in the normally pigmented southern African Negroid population and at a lower frequency in individuals from central Africa (0.002; 2/834), including individuals from Zambia, Cameroon, Zaire and the CAR. The study confirms the African origin of this deletion allele. Haplotype analysis suggests that the deletion mutation probably occurred only once and that it arose before the divergence of these African populations, which is estimated to be about 2000-3000 years ago. The unusually high frequency of OCA2 mutations, in particular the 2.7-kb deletion, suggests some selective agent or genetic drift.
眼皮肤白化病（OCA2）是南非黑人种群中最常见的常染色体隐性疾病，发病率为1/3900。OCA2基因座P已被定位于15号染色体q11 - q13，并且发现一个2.7kb的间质性缺失是非洲的常见突变。本研究报告了在来自南部非洲、赞比亚和中非共和国（CAR）黑人种群的OCA2患者个体中检测到该缺失等位基因（分别为0.77，131/170条OCA2染色体；0.79，11/14；0.33，4/12）。还对来自不同非洲国家的正常色素沉着个体进行了检测。在正常色素沉着的南部非洲黑人种群中，该缺失突变的频率为0.013（10/780），在来自中部非洲的个体（包括来自赞比亚、喀麦隆、扎伊尔和中非共和国的个体）中频率较低（0.002；2/834）。该研究证实了这个缺失等位基因起源于非洲。单倍型分析表明，该缺失突变可能仅发生过一次，并且发生在这些非洲种群分化之前，据估计分化时间约在2000 - 3000年前。OCA2突变，特别是2.7kb缺失的异常高频率表明存在某种选择因素或遗传漂变。
