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.
|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