ARPKD Known PKHD1 Variant Linkage Analysis for Informativity (PKDL) and Prenatal Linkage (PKDPL)
Information for Ordering
Acceptable Specimen TypesPlease send samples from the parents and their children for informativity results
• Fresh blood sample (3-6 ml EDTA; no time limitations associated with receipt)
• Paraffin-embedded tissue blocks or whole tissue from affected individual
• For prenatal samples, 2 T25 flasks of cultured CVS (>70% confluent) or 2 T25 flasks of cultured amniocytes (>70% confluent)
• Please provide fresh blood sample (3-6 ml, EDTA) for maternal cell contamination studies with (or in advance) of submitted specimen. A delay in receipt may delay turnaround time
Average = 20 working days (PKDL)
6 working days for prenatal testing (PKDPL)
$400/individual tested (USD – institutional/self-pay)
$500/individual for prenatal testing (USD – institutional/self-pay)
CPT: 81265
Z code: ZB67G
Candidates for Testing
ARPKD testing services are offered to established patients and families with previously identified PKHD1 mutations who wish to know if they are carriers before initiating another pregnancy.
Please find specimen requirement specifications above.
All submitted specimens must be sent at room temperature. DO NOT ship on ice.
Specimens must be packaged to prevent breakage and absorbent material must be included in the package to absorb liquids in the event that breakage occurs. Also, the package must be shipped in double watertight containers (e.g. a specimen pouch + the shipping company’s diagnostic envelope).
To request a sample collection kit, please click here or email medgenomics@uabmc.edu to complete the specimen request form.
Please contact the MGL (via email at medgenomics@uabmc.edu, or via phone at 205-934-5562) prior to sample shipment and provide us with the date of shipment and tracking number of the package so that we can better ensure receipt of the samples.
About
Disorder BackgroundAutosomal Recessive Polycystic Kidney Disease (ARPKD) is characterized by enlarged cystic kidneys and hepatic fibrosis. The diagnosis is often made pre- or neonatally, but some patients are still diagnosed later in life. The severity varies widely, with a high mortality rate in the first months of life. ARPKD is one of the more common hereditary childhood nephropathies with an estimated incidence of 1:20,000-1:40,000. The carrier frequency in the general population is estimated to be 1 in 70 to 1 in 100. Variants in PKHD1 are scattered throughout the gene. Most families carry their own “private” variants. For more information on the condition please refer to the review on the GeneTests website and Online Mendelian Inheritance in Man.
The gene for ARPKD, PKHD1 (Polycystic Kidney and Hepatic Disease 1), resides on chromosome 6p21-p12, spans 470 kb of genomic DNA and is the only gene known to be associated with the wide clinical spectrum of autosomal recessive polycystic kidney disease. 86 exons have been identified and multiple alternative transcripts are known. Over 300 variants have been reported. Missense, nonsense, frameshift, splicing and multi-exon deletions can occur and are located throughout the length of the gene, with no major variant hotspots known, as shown in the PKHD1 variant database.
We offer targeted detection of a previously characterized pathogenic variant within the family. From a fresh EDTA blood sample, DNA is extracted directly and the target region is amplified and directly sequenced. To offer this testing service, the proband’s variant must be identified by our laboratory before testing relatives.
Linkage studies are based upon the accurate clinical diagnosis of ARPKD in the affected family member and accurate delineation of the biological relationships in the family. Linkage studies also depend on the availability and/or willingness to be tested of at least the proband and both parents. Linkage analysis is performed by amplifying 6 highly informative microsatellite markers residing intragenically and closely flanking the PKHD1 gene.
Paraffin-embedded tissue as well as a cell line, tissue biopsy or blood sample can be used as the starting material from the affected proband for testing. In cases where only 1 pathogenic variant was identified by direct sequencing of the entire longest open reading frame, linkage studies can be applied for future prenatal diagnosis, if clinical diagnosis in the proband was accurate. Prenatal linkage based testing is available starting from direct or cultured CVS, fresh or cultured amniocytes.
REFERENCES available here.
Other related test options:
For more information, test requisition forms, or sample collection and mailing kits, please call: 205-934-5562.