Preferred test for molecular confirmation of a suspected clinical diagnosis of autosomal dominant polycystic kidney disease (ADPKD).
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 2 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is typically an adult-onset, multisystem disorder. Renal findings include: bilateral renal cysts, renal insufficiency, renal pain, hypertension, dilated renal tubules, enlarged kidneys, and end-stage renal disease (ESRD). Extra-renal findings include cysts in other organs, including liver, pancreas, seminal vesicles, and arachnoid membrane. Connective tissue findings include intracranial aneurysms, dolichoectasia, dilation of the aortic root, aortic dissections, mitral valve prolapse, and abdominal wall hernias. Fifty percent of individuals with ADPKD will develop ESRD by age 60.
Prevalence: 1:500-1:1,000 in the U.S.
Inheritance: Autosomal dominant; 5-10 percent of cases are de novo.
Penetrance: Age-dependent; nearly all older adults develop multiple renal cysts. The average age of onset for ESRD in individuals with PKD1 and PKD2 mutations is 54 and 74 years, respectively.
Cause: Pathogenic PKD1 or PKD2 gene mutations. In cases with an identifiable molecular cause, 85 percent are attributed to PKD1 and 15 percent are attributed to PKD2.
Clinical Sensitivity: 90 percent for ADPKD. Approximately 87 percent of cases are due to sequence variants and up to 3 percent of cases result from large deletions/duplications in PKD1 or PKD2.
Methodology: Bidirectional sequencing of the entire coding region and intron/exon boundaries of the PKD1 and PKD2 genes. A large region of PKD1, including exons 1-33, is duplicated six times on the same chromosome; therefore, to distinguish the PKD1 gene from the PKD1-like pseudogenes, long range PCR followed by site-specific PCR is used to sequence PKD1 exons 1-33. Multiplex ligation-dependent probe amplification (MLPA) is used to detect large exonic deletions/duplications of PKD1 or PKD2.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations and deep intronic mutations in PKD1 or PKD2 will not be detected. Large deletions/duplications of PKD1 exons 1, 2, 4, 8, 17, 24, 28, 32, 34, and 45 will not be detected. Mosaic mutations in PKD1 or PKD2 may not be detected. Breakpoints for large deletions/duplications will not be determined. Mutations in genes other than PKD1 and PKD2 are not assessed by this assay.
|Component Test Code*||Component Chart Name||LOINC|
|2012251||ADPKD Seq and Del/Dup Specimen||31208-2|
|2012252||ADPKD Seq, Del/Dup Interp||35474-6|
- Adult polycystic kidney disease (APKD)
- Autosomal dominant polycystic kidney disease
- Polycystic kidney disease type 1
- Polycystic kidney disease type 2