> Overview

> DNA Analysis

> Chromosomal Analysis

> FISH

> Parentage

DNA Analysis:

Cystic Fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder with an incidence of 1 in 2,500 to 3,300 live births in Caucasian populations. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene located on chromosome 7. Greater than 900 mutations have been identified in the CFTR gene. The majority of these mutations are rare, occurring at frequencies of less than 0.1%. The most common mutation, ∆F508, is found on approximately 30% - 80% of CF chromosomes depending on ethnicity. It is estimated that one in 29 individuals in Caucasian and Ashkenazi Jewish populations, one in 46 Hispanic Americans, one in 65 African Americans, and one in 90 Asian Americans carry a CFTR mutation.

Indications for Testing

• Carrier screening
• Individuals with a family history of CF
• Prenatal diagnosis for confirmed CF carriers
• Confirmation of a CF diagnosis in affected individuals
• Abnormal fetal ultrasound
• Gamete donors

See CFTR Intron 8 Poly(T) Variant (CBAVD) for CF testing on healthy males with obstructive azoospermia.

Testing Methodology

Direct mutation analysis: Our laboratory utilizes an automated high-throughput CF-OLA protocol involving polymerase chain reaction (PCR) amplification of specific regions of the CFTR gene followed by probing of the amplified regions using the Oligonucleotide Ligation Assay. The CF assay detects a panel of 31 mutations in the CFTR gene including the 23 mutations currently being recommended for population based carrier screening by the American College of Medical Genetics and the American College of Obstetricians and Gynecologists.

CF mutation panel:

* Reflex testing for the intron 8 poly(T) variant is performed for individuals testing positive for the R117H mutation and when clinically indicated. Reflex testing for the I506V and I507V polymorphisms is performed for healthy individuals who test as F508 or I507 homozygotes.

Sensitivity

Mutation detection rates: This assay will detect approximately 90% of mutations in the Caucasian (Non-Hispanic) population, 97% in the Ashkenazic Jewish population, 69% in the African American population, and 73% in the Hispanic American population. Data is not yet available for the Asian American population.

Specimen Requirements

Blood: For adults, 5 cc collected in a purple top (EDTA) or yellow top (acid citrate dextrose) vacutainer tube. For children, 1 - 2 cc is sufficient. Do not centrifuge or freeze. Sample may be refrigerated or stored at room temperature.

Please contact the laboratory at 858-534-3093 for information on prenatal testing and buccal swab sampling on newborns. A blood sample from the mother is required for prenatal testing to rule out maternal cell contamination.

Turnaround Time

10–12 days

CPT Codes

83891, 83900, 83901, 83909, 83912, 83914

For prenatal studies add 88235

Forms and Transport & Shipping Informtaion

> Medical Genetics Test Requisition Form

> Standard DNA Consent Form

> Medical Genetics Specimen Transport and Shipping Information