Allele frequencies in a worldwide survey of a CA repeat in the first intron of the CFTR gene

The dinucleotide CA repeat within intron 1 of the CFTR gene has recently be en identified, We have determined the allele frequencies of this polymorphi sm in samples from 18 populations covering all major geographical areas, wi th a total of 1,816 chromosomes. When considering allele distributions, Afr ican populations presented a wider range of alleles than other populations and also presented higher expected heterozygosities. Analysis of molecular variance showed that 8.04% of the genetic variance in this locus could be a ttributed to differences among populations. We concluded that the polymorph ism in the CA repeat in intron 1 of the CFTR gene is highly informative in populations from all geographical regions of the world. Thus, it can be app lied to family studies of unknown mutations causing cystic fibrosis (CF) an d can provide valuable information for genetic counseling, Moreover, its an alysis should be included in the haplotypic analysis of known CF mutations.