Molecular Diagnostics in Autosomal Dominant Polycystic Kidney Disease

Abstract

Background and objectives: Gene-based mutation screening is now available and has the potential to provide diagnostic confirmation or exclusion of autosomal dominant polycystic kidney disease. This study illustrates its utility and limitations in the clinical setting. Design, setting, participants, & measurements: Using a molecular diagnostic service, genomic DNA of one affected individual from each study family was screened for pathologic PKD1 and PKD2 mutations. Bidirectional sequencing was performed to identify sequence variants in all exons and splice junctions of both genes and to confirm the specific mutations in other family members. In two multiplex families, microsatellite markers were genotyped at both PDK1 and PKD2 loci, and pair-wise and multipoint linkage analysis was performed.Results: Three of five probands studied were referred for assessment of renal cystic disease without a family history of autosomal dominant polycystic kidney disease, and two others were younger at-risk members of families with autosomal dominant polycystic kidney disease being evaluated as living-related kidney donors. Gene-based mutation screening identified pathogenic mutations that provided confirmation or exclusion of disease in three probands, but in the other two, only unclassified variants were identified. In one proband in which mutation screening was indeterminate, DNA linkage studies provided strong evidence for disease exclusion.Conclusions: Gene-based mutation screening or DNA linkage analysis should be considered in individuals in whom the diagnosis of autosomal dominant polycystic kidney disease is uncertain because of a lack of family history or equivocal imaging results and in younger at-risk individuals who are being evaluated as living-related kidney donors.

Family History of Renal Disease Severity Predicts the Mutated Gene in ADPKD

“…We genotyped all of the available study participants with five simplesequence repeat markers each at the PKD1 and PKD2 loci using an established protocol. 22 The locations of these markers relative to the PKD1 locus are shown as follows (the number between markers denotes intermarker distance in cM): HBAP1-2.0-PKD1-0.1-CW4-0.1-SM6-0.6-D16S2618-2.0-D16S423. The locations of these markers relative to the PKD2 locus are shown as follows (the number between markers denotes intermarker distance in cM): D4S231-2.0-D5S1534-2.3-SPP1-0.2-PKD2-0.5-D4S1563-2.0-D4S423.…”

“…11,22 In suspected families who had PKD2 and in which we failed to identify any pathogenic mutation and in selected families suspected to have PKD1, sequence analysis of both PKD1 and PKD2 was performed in a clinically affected subject using a commercial diagnostic service (Athena Diagnostics, Worcester, MA; http://www.athenadiagnostics.com/content/test-catalog/find-test/service). Briefly, genomic DNA was used for locus-specific long-range PCR amplification of eight segments encompassing the entire PKD1 duplicated region.…”

“…All 71 PCR products were bidirectionally sequenced, including the coding regions and exon-intron splice junctions of both genes. 22 …”

Linkage Analysis of Autosomal Dominant Polycystic Kidney Disease in Iranian Families through PKD1 and PKD2 DNA Microsatellite Markers

“…Two microsatellite markers (16AC2.5 and KG8) are localized within 350kb of the PKD1 gene (5, 9-11). D4S423 and D4S231 (specific markers) were used to assess linkage to PKD2 (5,12,13).…”

Hereditary polycystic kidney disease: genetic diagnosis and counseling

“…Genetic linkage analysis with polymorphic markers within and/or near genes and which define haplotypes, complements the direct tests, and gene sequencing is the most direct of them (C). 24 The haplotype analysis is quick, simple and low cost, but depends on the possibility of analyzing a minimum number of relatives knowingly affected and unaffected within a family, which is not always possible.…”