Purpose: It is recommended that cystic fibrosis (CF) carrier screening be made available to African Americans who are either pregnant or planning a pregnancy. We analyzed the carrier and mutant allele frequencies for African Americans undergoing CF carrier screening in our laboratories.
Methods: Between December 2001 and September 2003, we performed carrier screening for 2189 African Americans, testing for at least the 25 recommended mutations.
Results: A total of 33 CF carriers were identified. The most common mutations detected were deltaF508, G622D, R117H/7T, and G551D. The G622D allele frequency among African Americans was 0.18%. We did not detect any 3120 + 1G --> A carriers, although 4 were expected (P < 0.05).
Conclusions: When considering only the 25 recommended CF mutations, 1 in 75 African Americans screened in our laboratories were carriers (within the expected range, given a 69% mutation detection rate). The addition of 2 mutations, G622D and Q98R (incidentally identified while screening for ACOG/ACMG mutations), increased the observed carrier frequency to 1 in 66, which is not significantly different from the known African American carrier frequency of 1 in 65. The frequencies of several specific mutations detected were unanticipated, as was the absence of 3120 + 1G --> A carriers. Further studies on African American patients with classic CF are needed to examine the incidence of CF mutations that are not part of the current panel, such as G622D.