Clemens P R, Fenwick R G, Chamberlain J S, Gibbs R A, de Andrade M, Chakraborty R, Caskey C T
Institute for Molecular Genetics, Baylor College of Medicine, Houston, TX 77030.
Am J Hum Genet. 1991 Nov;49(5):951-60.
To improve carrier detection and prenatal diagnosis for Duchenne and Becker muscular dystrophy families, we determined allele frequencies and measures of variation for four (dC-dA)n.(dG-dT)n loci identified within a deletion-prone region of the human dystrophin gene. The loci are highly polymorphic, with predicted heterozygosities of 71.6%-93.3%. Direct DNA sequence analysis of the (dC-dA)n.(dG-dT)n locus in intron 49 revealed an additional length polymorphism which varies by single-basepair increments, is adjacent to the dinucleotide repeat block, and enhances the polymorphic content of this marker. The four (dC-dA)n.(dG-dT)n loci are each easily amplified by PCR in two diplex reactions. The variability of allele lengths at these loci makes them ideal for carrier detection and prenatal diagnosis, often providing diagnostic information when RFLP analysis is uninformative. These markers have aided in identification of deletion mutations, exclusion of maternal cell contamination of chorionic villus samples, confirmation of paternity, and mapping of gene recombinations. The allele identification of these loci can be performed either with a radiolabel or with an automated, nonradioactive, fluorescent gel detection system.
为改善杜氏和贝克肌营养不良症家庭的携带者检测及产前诊断，我们测定了人类肌营养不良蛋白基因易缺失区域内4个（dC-dA）n.（dG-dT）n位点的等位基因频率及变异指标。这些位点高度多态，预测杂合度为71.6%-93.3%。对内含子49中（dC-dA）n.（dG-dT）n位点进行直接DNA序列分析，发现了另一种长度多态性，其以单碱基对增量变化，毗邻二核苷酸重复序列块，并增加了该标记的多态性含量。4个（dC-dA）n.（dG-dT）n位点均可通过两次双重PCR反应轻松扩增。这些位点等位基因长度的变异性使其非常适合携带者检测和产前诊断，在限制性片段长度多态性（RFLP）分析无信息时，常常能提供诊断信息。这些标记物有助于缺失突变的鉴定、绒毛膜绒毛样本母源细胞污染的排除、父权确认及基因重组图谱绘制。这些位点的等位基因鉴定既可用放射性标记进行，也可用自动化非放射性荧光凝胶检测系统进行。
