The incidence of cystic fibrosis in Scotland calculated from heterozygote frequencies.
The incidence of cystic fibrosis (CF) has previously been calculated from epidemiological surveys and from neonatal screening. With the cloning of the CF gene it has become possible to derive incidence figures from heterozygote frequencies, provided that the distribution of mutant alleles among healthy carriers is the same as among affected people. We have estimated the allele frequencies for four CF mutations, AF508, G551D, G542X and R117H, in 14360 unselected women undergoing antenatal heterozygote screening. The proportion of R117H, an allele of known mild effect, was much greater for heterozygotes than for homozygotes. The incidence of CF was therefore calculated from the heterozygote frequencies of AF508, G551D and G542X in a larger cohort of 27 161 successively screened women. The point estimate for the incidence of CF in the Scottish population was 1 in 1984, with 95% confidence intervals of 1 in 1692 to 1 in 2336.
Brock
D J
DJ
Human Genetics Unit, The University of Edinburgh, Molecular Medicine Centre, Western General Hospital, UK.
Gilfillan
A
A
Holloway
S
S
D000483:Alleles; D003550:Cystic Fibrosis / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D006579:Heterozygote; D006801:Humans; D015994:Incidence; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012606:Scotland / Q000453:epidemiology