ARUP's Laboratory Test Directory

Alport Syndrome, X-linked (COL4A5) Sequencing : 0051786
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Patient History for Alport Syndrome Testing
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Additional Technical Information


Mnemonic: ALPORT FGS

Ordering Recommendation: Diagnostic testing for X-linked Alport syndrome. Carrier screening for X-linked Alport syndrome. Predictive testing for X-linked Alport syndrome.
Methodology: Polymerase Chain Reaction/Sequencing
Performed: Varies
Reported: Within 28 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA) or yellow (ACD Solution A or B).

Specimen Preparation: Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature: Refrigerated.

Stability (collection to initiation of testing): Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Interpretive Data: 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: Rare diagnostic errors can occur due to primer site mutations. 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 at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
CPT Code(s): 81479