Acceptable first-line genetic test for the detection of mutations causing X-linked Alport syndrome.
- 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: 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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|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