Molecular Test Listing

Molecular Requisition

Polycystic Kidney Disease: Linkage Analysis

 

The most common form of Polycystic Kidney Disease, type1 (PKD1) is inherited in an autosomal dominant pattern. The PKD1 gene, polycystin (chromosome 16) is responsible for about 85% of PKD. The disease causes cysts in the kidney which can lead to a progressive degeneration of the kidney, and eventually failure. In the United States, 1 in 1000 newborns is at risk for developing PKD. Onset generally occurs after age 35, and roughly 60% of individuals with the disease will have renal failure by age 50. About 10% of end-stage renal disease is a result of PKD. Because of variable expression and age of onset, affected individuals can be born to parents without an apparent history of PKD. The disease often results in hypertension years in advance of kidney symptoms.

The second most common form of the disease, Polycystic Kidney Disease, type2 (PKD2), is a result of the PKD2 gene, polycystin 2, on chromosome 4. PKD2 is also inherited in an autosomal dominant manner, and  is responsible for about 15% of PKD. It is generally indistinguishable clinically from PKD1, the most common form of PKD. Complications have been described involving cysts in the liver and its ducts as well as "berry" aneurysms. It is generally recommended to test both PKD1 and PKD2 in conjunction, to provide the most accurate assessment of risk.

 

REASONS FOR REFERRAL:
  • Individuals with a family history of PKD who wishes to undergo prenatal or preconception testing.
  • Individuals with hypertension and a family history PKD.
  • Individuals desiring to be a kidney donor for an affected family member.
  • To determine whether the PKD1 or PKD2 gene is responsible for the disease in the family.

TESTING METHODOLOGY:
  • Linkage: Testing involves tracking the gene through the family using highly polymorphic microsatellite markers surrounding, or within the gene, by PCR technology.
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    • The choice of testing strategy involves many factors. A discussion with the laboratory is recommended before sending a specimen.

    •  This approach can be the most informative stratagem for eliminating risk; however, it requires samples from multiple critical family members, including at least two affected individuals. An accurate family history is essential for correct interpretation of results.

    SPECIMEN REQUIREMENTS:
    • Basic pedigree detailing clinical history.
    • Blood EDTA (purple top) tubes:  

                Newborn: minimum 1-2 mL          

                Child/Adult: prefer 2 tubes of 3-5 mL

    • Alternate sample: Paraffin block, or 5 unstained sections on slides from the block.

  • A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.

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    TURNAROUND TIME:     3 weeks

    CPT CODES: