Berkshire Health System Laboratories

BERKSHIRE HEALTH SYSTEM LABORATORIES

Berkshire Medical Center

Fairview Hospital

Cystic Fibrosis

Name and Intended Use

We employ the Invader® Cystic Fibrosis (CF) Diagnostic Assay panel using the CFTR InPlex™ Card. Thirty eight mutations are examined using DNA isolated from peripheral blood. ACOG now recommends DNA screening for all couples seeking preconception or prenatal care

Summary and Explanation

CF is one of the most common genetic diseases in Caucasians, with an incidence of about 1 in 3,300. The disease also has a fairly high incidence among Hispanics, 1 in 9,500. CF is a rare disorder in native Africans and native Asians, estimated to occur in less than 1 in 50,000, but higher incidences are observed in American populations of these ethnic groups (1 in 15,300 and 1 in 32,100, respectively), suggesting Caucasian admixture. Recent surveys of some Native-American populations also indicate high incidences. The relatively high incidence and concomitant high frequency of carriers motivated the proposal of population-based screening. In April 2001, the American College of Obstetricians and Gynecologists (ACOG) and the American College of Medical Genetics (ACMG) issued a guideline publication for physicians recommending a pan-ethnic panel test of 25 mutations (Grody et al., 2001) plus six reflex tests. ACOG now recommends DNA screening for all couples seeking preconception or prenatal care -- not just those with a personal or family history of CF, as previously recommended.

Principle of the Procedure

Because the invader reaction is to be done on each of 44 mutation sites, a primary PCR reaction is performed to enrich the CFTR gene. The PCR reaction is carried out for 14 cycles. The CFTR gene is amplified in 16 amplicons which are all subjected to the Invader reaction.

The biplex format of the Invader® DNA Assay enables simultaneous detection of two DNA sequences in a single well. Most often, this involves detection of two variants of a particular polymorphism. The biplex format uses two different discriminatory Primary Probes, each with a unique 5'-flap, and two different FRET™ Cassettes, each with a spectrally distinct fluorophore. By design, the released 5'-flaps will bind only to their respective FRET™ Cassettes to generate a target-specific signal.

Specimen: Lavender top blood tube.

Informed consent form for genetic testing is required.

Turnaround Time: 1 week.

Approved by:
Medical Director: C. Abbott, MD / Adopted: 1-8-08
Approved by:
Technical Director: R. Intres, PhD / Revised:
Prepared by:
Technologist: R. Intres, PhD / Reviewed: 2-14-12 RI