| 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.
Refer to Statement C under Testing Information at http://www.aruplab.com.
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| CPT Code(s): |
Sequencing: 83891 Isolation; 83898 x46 Amplification; 83904 x46 Sequencing; 83909 x2 capillary electrophoresis.
Del/Dup: 83896 x2 Nucleic Acid Probes; 83898 x2 Amplification; 83914 x2 Extension; 83909 x2 Capillary Electrophoresis; 83912 Interpretation and report - Additional CPT code modifiers may be required for procedures performed to test for oncologic or inherited disorders.
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