Acceptable genetic test for the detection of variants causing X-linked Alport syndrome.
Polymerase Chain Reaction/Sequencing
Lavender (EDTA), pink (K2EDTA) or yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Background Information for Alport Syndrome, X-linked (COL4A5) Sequencing:
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: Estimated to be between 1 in 5,000 to 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: Type 4 collagen (COL4A5) alpha chain mutations.
Clinical Sensitivity: Greater than 80 percent for X-linked Alport syndrome.
Methodology: Bidirectional sequencing of the entire COL4A5 coding region and intron-exon boundaries.
Analytical Sensitivity & Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region and deep intronic mutations will not be detected. Large deletions/duplications will not be detected in females. Mutations in genes other than COL4A5 are not evaluated.
Laboratory Developed Test (LDT)
|Component Test Code*||Component Chart Name||LOINC|
|0051787||Alport Syndrome (COL4A5) Sequencing|
|2001337||ALPORT FGS Specimen|
- Alport syndromesequencing assay
- X-linked Alport syndrome molecular testing