De Braekeleer M, Gauthier S
Department of Human Sciences, University of Quebec at Chicoutimi, Canada.
Hum Biol. 1996 Jun;68(3):371-81.
Saguenay-Lac-St-Jean is a geographically isolated region of northeastern Quebec in which several autosomal recessive disorders have a high incidence. The kinship coefficients of all possible pairs of 567 probands were calculated and compared with those of 1701 matched control individuals. The mean kinship coefficient of the group containing all 567 probands was 5.57 times higher than that of the control group (0.000981 versus 0.000176). Overall, 45.5% of the probands were third-degree cousins, compared with 32.9% of the control group. However, in each disorder only a few probands were traced back to the most represented founder couple in Saguenay-Lac-St-Jean. Molecular data added a new dimension to the concept of kinship by showing that at least in the study area, closely related individuals do not necessarily carry identical mutations, which, in turn, may have a great impact on carrier screening. Our results strongly suggest that the high incidence of autosomal recessive disorders in Saguenay-Lac-St-Jean is the result of a founder effect.
萨格奈-圣让湖地区是魁北克省东北部一个地理上孤立的区域，在该地区几种常染色体隐性疾病发病率很高。计算了567名先证者所有可能配对的亲属系数，并与1701名匹配的对照个体的亲属系数进行比较。包含所有567名先证者的组的平均亲属系数比对照组高5.57倍（分别为0.000981和0.000176）。总体而言，45.5%的先证者是三级表亲，而对照组这一比例为32.9%。然而，在每种疾病中，只有少数先证者追溯到萨格奈-圣让湖地区最具代表性的奠基夫妇。分子数据通过表明至少在研究区域内，亲缘关系密切的个体不一定携带相同的突变，为亲属关系的概念增添了新的维度，这反过来可能对携带者筛查产生重大影响。我们的结果有力地表明，萨格奈-圣让湖地区常染色体隐性疾病的高发病率是奠基者效应的结果。
