[Molecular genetic analysis of TUB18 and TUB20 intragenic polymorphism and various mutations of the CFTR gene in the Moscow region]

Abstract

Allelic frequencies of two intron polymorphisms in the cystic fibrosis transmembrane regulator (CFTR) gene, TUB18 and TUB20, were estimated on chromosomes of 67 cystic fibrosis patients and on that of 37 healthy donors from Moscow and the Moscow oblast. Allele 2 of the TUB 18, and allele 1 of the TUB20 were 2.1 and 1.5 times more frequent on the non-delta F508 chromosomes of the cystic fibrosis patients than on chromosomes of healthy donors, i.e. these alleles were in linkage disequilibrium with the CFTR gene. Allele 1 of the TUB18 marker and allele 2 of the TUB20 marker demonstrated absolute linkage disequilibrium with the delta F508 mutation of the CFTR gene. The degree of association between the TUB18 and TUB20 intron polymorphisms and the GATT and T854T intragenic polymorphisms was analyzed. Of all 62 delta F508 chromosomes tested, 98.3% shared the 2-1-1-2 GATT- T854T-TUB18-TUB20 haplotype. Eight major (more frequent) GATT-T854T-TUB18-TUB20 haplotypes were found in 89.5% of normal, and in 97.9% of non-delta F508 chromosomes of cystic fibrosis patients from the Moscow region. Three of these major haplotypes, 2-1-1-2, 1-2-2-1, and 2-2-1-2, were respectively 2.5, 2, and 1.5 times more frequent on non-delta F508 cystic fibrosis chromosomes than on normal chromosomes. Data on screening for the G542X, N1303K, and 394delTT mutations of the CFTR gene, carried out on 134 chromosomes of cystic fibrosis patients from the Moscow region are presented. The frequencies of the G542X and 394delTT mutations were estimated as 1.5%, while the frequency of the N1303K mutation was 2.2%.