This is a second tier test and REQUIRES PERMISSION from ARUP's Genetic Counselor (800-242-2787, x2141) before ordering. Preferred initial test is the sequencing and deletion/duplication test.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Progressive renal and cochlear disease with 30-40 percent incidence of ocular involvement; 60 percent of males reach end-stage renal disease by age 30, and 85 percent have sensorineural deafness by age 40.
Incidence: Approximately 1 in 50,000 live births.
Inheritance: X-linked recessive; de novo mutations in 10-15 percent of affected males.
Penetrance: Variable, depending on mutation and sex.
Cause: Pathogenic type 4 collagen alpha chain 5 (COL4A5) mutations.
Clinical Sensitivity: Approximately 10 percent of X-linked Alport syndrome is due to large COL4A5 gene deletions or duplications.
Methodology: Multiplex ligation-dependent probe amplification (MLPA) to detect large COL4A5 coding region deletions/duplications.
Analytical Sensitivity & Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Breakpoints for large deletions/duplications will not be determined. COL4A5 base pair substitutions, small deletions/duplications, deep intronic, and regulatory region mutations will not be detected. Mutations in genes, other than COL4A5, are not evaluated. Deletions/duplications in exons 8, 25, 40, 42, and 43 of the COLA5 gene will not be detected.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2002395||Alport Syndrome (COL4A5) Del/Dup Interp||53853-8|
|2002396||ALPORT DD Specimen||31208-2|
- Alport syndrome deletion/duplication assay
- X-linked Alport syndrome molecular testing