ARUP's Laboratory Test Directory

Alport Syndrome, X-linked (COL4A5) Deletion/Duplication : 2002394
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Patient History for Alport Syndrome Testing
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Additional Technical Information


Mnemonic: ALPORT DD

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/Multiplex Ligation-dependent Probe Amplification
Performed: Varies
Reported: Within 14 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) Deletion/Duplication
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: Rare diagnostic errors can occur due to probe site mutations. 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 evalutated.



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