Download Genetic Analysis of CFTR Cystic Fibrosis is caused by mutations in

Genetic Analysis of CFTR
Cystic Fibrosis is caused by mutations in the CFTR protein. This large protein in encoded by the
189 kilobase CFTR gene. While over 1500 known mutations in CFTR have been documented,
only a fraction of are known to be of clinical significance. The most common mutation is the
deltaF508 mutation, which accounts from 67% of the mutations world-wide and approximately
70% to 75% in a North American Causasian population.
Sweat chloride concentration remains the gold standard for diagnosis of Cystic Fibrosis. Sweat
chloride analysis is recommended over analysis of the CFTR gene. Sweat collection is performed
by appointment in the SLCH Outpatient Laboratory (314-454-4143).
Policy
Mayo Medical Laboratories is the SLCH preferred reference laboratory for genetic testing for
CF. The first-line test is Cystic Fibrosis Mutation Analysis, 106-Mutation panel. These 106
mutations account for 91% of CF chromosomes in a Northern European Population, 81% of
African American, and 82% of Hispanic. The table below describes the carrier frequency and
mutation detection rate in different racial or ethnic groups. The maximum turn around time for
this analysis is 7 days. The specimen volume requirement is 0.5 ml whole blood.
Sequencing of the full gene can be sent upon a negative mutation panel. If an order for full
gene sequencing is received without mutation panel resulted, the full gene order will be
canceled and the mutation panel will be ordered. Analysis of the full gene can be added-on to
the existing specimen when mutation panel results are released; no additional specimen is
required.
African American
Carrier
Frequency
1/65
Mutation Detection
Rate*
81%
Ashkenazi Jewish
1/25
97%
Asian American (excluding individuals of Japanese
ancestry)
1/90
54%
Mixed European
1/25
82%
Eastern European
1/25
77%
French Canadian
1/25
91%
Hispanic American
1/46
82%
Northern European
1/25
91%
Southern European
1/25
79%
Racial or Ethnic Group