ARUP's Laboratory Test Directory

Alport Syndrome, X-linked (COL4A5) Sequencing and Deletion/Duplication : 2002398
[ image for: Patient History for Alport Syndrome Testing]
Patient History for Alport Syndrome Testing
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Additional Technical Information


Mnemonic: ALPORT FGA

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/Multiplex Ligation-dependent Probe Amplification
Performed: Varies
Reported: Within 35 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B).

Specimen Preparation: Transport 3 mL whole blood. (Min: 2 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 and 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: Greater than 80 percent for X-linked Alport syndrome in males or females.
Methodology: Bidirectional sequencing of the entire COL4A5 coding region and intron-exon boundaries and multiplex ligation-dependent probe amplification (MLPA) to detect large COL4A5 coding region deletions and duplications.
Analytical Sensitivity & Specificity: 99 percent.
Limitations: Rare diagnostic errors can occur due to primer or probe site mutations. Regulatory region mutations and deep intronic mutations will not be detected. Breakpoints of deletions/duplications will not be determined. 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 (2)