- 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: 3 days; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics of Nonclassic Cystic Fibrosis (CF): Findings are often limited to a single organ system such as isolated pancreatitis, bilateral absence of the vas deferens, nasal polyposis, or bronchiectasis.
Incidence of Classic CF: 1 in 3,000 Caucasians or Ashkenazi Jewish, 1 in 8,000 Hispanics, 1 in 15,000 African Americans, 1 in 32,000 Asians.
Incidence of Nonclassic CF: Unknown.
Inheritance: Autosomal recessive.
Penetrance: High for severe mutations, variable for mild mutations.
Cause of Nonclassic CF: Typically one severe and one mild/moderate CFTR mutations on opposite chromosomes.
Mutations Tested: G85E (c.254G>A), R117H (c.350G>A), R334W (c.1000C>T), R347P (c.1040G>C), R347H (c.1040G>A), 394delTT (c.262_263delTT), A455E (c.1364C>A), I507del (c.1519_1521de;ATC), F508del (c.1521_1523de;CTT), V520F (c.1558G>T), G542X (c.1624G>T), S549N (c.1646G>A), S549R (c.1647T>G), G551D (c.1652G>A), R553X (c.1657C>T), R560T (c.1679G>C), 621+1G>T (c.489+1G>T), 711+1G>T (c.579+1G>T), 1078delT (c.948delT), R1162X (c.3484C>T), W1282X (c.3846G>A), N1303K (c.3909C>G), 1717-1G>A (c.1585-1G>A), 1898+1G>A (c.1766+1G>A), 2183AA>G (c.2051_2052delAAinsG), 2184delA (c.2052delA), 2789+5G>A (c.2657+5G>A), 3120+1G>A (c.2988+1G>A), 3659delC (c.3528delC), 3849+10kbC>T (c.3717+12191C>T), 3876delA (c.3744delA), 3905insT (c.3773_3774insT). For specimens positive for R117H, the IVS-8/poly T (c.1210-12T[5_9] is analyzed. The mutations tested are listed above according to the legacy nomenclature; the standard nomenclature is listed in parentheses. Panel mutations are reported according to the legacy nomenclature.
Clinical Sensitivity: Ashkenazi Jewish 94 percent; Caucasian 89 percent; Hispanic 73 percent; African American 65 percent; Asian American 55 percent.
Methodology: PCR, oligonucleotide ligation assay (OLA), fluorescent hybridization probes, and capillary electrophoresis.
Analytical Sensitivity & Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Only the 32 CFTR mutations listed above, and the IVS-8 poly T site, will be interrogated.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0055454||Cystic Fibrosis Atypical Mutation 1||42938-1|
|0055456||Cystic Fibrosis Atypical Mutation 2||42939-9|
|2002134||Cystic Fibrosis Atypical Interpretation||50398-7|
|2011722||Cystic Fibrosis (CFTR) 5T Mutation|
- nonclassic CF variants