Entezam M, Khatami M R, Saddadi F, Ayati M, Roozbeh J, Saghafi H, Keramatipour M
Tehran University of Medical Sciences Department of Medical Genetics, School of Medicine Tehran Iran.
Tehran University of Medical Sciences Nephrology Research Center Tehran Iran.
Cell Mol Biol (Noisy-le-grand). 2016 Feb 4;62(2):15-20.
Autosomal Dominant Polycystic Kidney Disease (ADPKD) caused by mutations in two PKD1 and PKD2 genes. Due to the complexity of the PKD1 gene, its direct mutation screening is an expensive and time-consuming procedure. Pedigree-based haplotype analysis is a useful indirect approach to identify the responsible gene in families with multiple affected individuals, before direct mutation analysis. Here, we applied this approach to investigate 15 appropriate unrelated ADPKD families, selected from 25 families, who referred for genetic counseling. Four polymorphic microsatellite markers were selected around each PKD1 and PKD2 loci. In addition, by investigating the genomic regions, two novel flanking tetranucleotide STR markers were identified. Haplotype analysis and calculating Lod score confirmed linkage to PKD1 in 9 families (60%) and to PKD2 in 2 families (13%). Linkage to both loci was excluded in one family (6.6%). In 2 families (13%) the Lod scores were inconclusive. Causative mutation was identified successfully by direct analysis in two families with confirmed linkage, one to PKD1 and another to PKD2 locus. The study showed that determining the causative locus prior to direct mutation analysis is an efficient strategy to reduce the resources required for genetic analysis of ADPKD families. This is more prominent in PKD2-linked families. Selection of suitable markers, and appropriate PCR multiplexing strategy, using fluorescent labeled primers and 3 primer system, will also add value to this approach.
常染色体显性多囊肾病（ADPKD）由两个PKD1和PKD2基因突变引起。由于PKD1基因的复杂性，其直接突变筛查是一个昂贵且耗时的过程。基于家系的单倍型分析是一种有用的间接方法，可在直接突变分析之前，在有多个患病个体的家庭中确定致病基因。在此，我们应用这种方法对从25个前来进行遗传咨询的家庭中挑选出的15个合适的无亲缘关系的ADPKD家庭进行研究。在每个PKD1和PKD2基因座周围选择了四个多态性微卫星标记。此外，通过对基因组区域的研究，鉴定出两个新的侧翼四核苷酸STR标记。单倍型分析和计算Lod分数证实，9个家庭（60%）与PKD1连锁，2个家庭（13%）与PKD2连锁。在一个家庭（6.6%）中排除了与两个基因座的连锁。在2个家庭（13%）中，Lod分数不确定。通过直接分析，在两个连锁得到确认的家庭中成功鉴定出致病突变，一个与PKD1连锁，另一个与PKD2基因座连锁。该研究表明，在直接突变分析之前确定致病基因座是减少ADPKD家庭遗传分析所需资源的有效策略。这在与PKD2连锁的家庭中更为突出。选择合适的标记以及使用荧光标记引物和三引物系统的适当PCR多重策略，也将为这种方法增添价值。
