Cystic Fibrosis Carrier Screening and Diagnostic Testing

Cystic Fibrosis

Cystic Fibrosis (CF) is an autosomal recessive disorder caused by deficiency of the protein produced by the CFTR gene. In addition, deficiency of CFTR can also cause congenital absence of the vas deferens (CAVD/CBAVD). Cystic fibrosis affects epithelia of the respiratory tract, exocrine pancreas, intestine, male genital tract, hepatobiliary system, and exocrine sweat glands, resulting in a complex, multisystem disease. Pulmonary disease is the major cause of morbidity and mortality in CF.

Cystic Fibrosis Carrier Screening

Next generation sequencing (NGS) improves the sensitivity of CF carrier screening by allowing the detection of more mutations in the CFTR gene. The efficiency of NGS results in higher carrier detection rates in all populations. The NGS assay has been designed in-house to cover all exons, all exon/intron boundaries, and clinically-relevant intronic regions. The NGS assay will not reliably detect large deletions (>30 bp, exon-level, or gene-level deletions).

Common indications for CF Carrier Screening include:

• Preconception testing
• Early pregnancy, prior to 18 weeks to allow time for prenatal testing if desired
• Family history of CF, provide CF mutation if known
• Partner is known CF carrier/ known to be affected with CF
• Congenital bilateral absence of vas deferens (CBAVD)
• Abnormal fetal ultrasound: echogenic bowel

A negative CF carrier screen significantly reduces but does not eliminate the carrier risk regardless of the methodology. The detection rate is dependent on the patient’s ethnic background.

CFTR Diagnostic Testing is not intended as a general screening test for healthy individuals with no family history of CF who have not first undergone CF carrier screening. For further discussion of specific cases, contact the laboratory genetic counselors or the molecular genetics laboratory director.

CFTR Known Familial Mutation Analysis is available for family members when a mutation has been identified. CFTR Prenatal Diagnosis is also available.

Common indications for CFTR Diagnostic Testing include:

• Confirmation of positive newborn screening of cystic fibrosis
• Confirmation of a clinical diagnosis of atypical cystic fibrosis
• Confirmation of a clinical diagnosis of congenital absence of vas deferens
• Targeted mutation analysis for known familial mutations in CFTR.
• Prenatal diagnosis of previous identified familial mutations in CFTR.

OMIM #: 219700 277180

Sample Requirements

• Infants: 2-3 mL whole blood in purple top EDTA tube
• Children (>2 years) and Adults: 3-4 mL whole blood in purple top EDTA tube
• Amniotic fluid or cultured amniocytes
• Chorionic villi or cultured chorionic villi
• Cultured skin fibroblasts, blood lymphocytes, and frozen tissue from biopsy may also be used for DNA analysis. Please contact lab for further details.

Please submit a completed Molecular Requisition for each sample.

Sample Handling

Blood samples stored overnight should be refrigerated or kept cold. Samples should never be frozen. Specimens being sent from outside facilities should be packaged according to standard medical safety practices with a cold pack. The specimen should be shipped by overnight priority (scheduled to arrive by Friday morning at the latest).

Shipping Address

Center for Human Genetics Laboratory
10524 Euclid Ave, Sixth Floor
Cleveland, OH 44106
216-983-1134

For local samples, please call Client Service (440-879-2930) to arrange for sample pick-up.

Turn Around Time

5-10 days

CPT Code

• Carrier Screening: 81220
• Diagnostic Testing (prenatal and postnatal): 81223
• Known Familial Mutation Testing (prenatal and postnatal): 81221