analysis of c.3369+213ta[7-56] and d7s523 microsatellites linked to cystic fibrosis transmembrane regulator.

cystic fibrosis (cf) is a life-limiting autosomal recessive disorder affecting principally respiratory and digestive system . it is caused by cystic fibrosis transmembrane conductance regulator (cftr) gene mutation. the aim of this study was to determine the extent of repeat numbers and the degree of heterozygosity for c.3499+200ta(7_56) and d7s523 located in intron 17b and 1 cm proximal to the cftr gene respectively. both microsatellites were analyzed by direct electrophoresis of pcr product on 20% polyacrylamide gel in 40 normal subjects and 40 cf patients originating from north iran. 9 different alleles were found for d7s523 ranging from 16 to 24 repeats alleles. (ca)20 was the most prevalent allele both in normal individuals and cf patients with 21.3% and 20% frequencies respectively. heterozygosity frequency of d7s523 in normal individuals and cf patients was 97.5% and 90% respectively. eighteen different alleles were found for c.3499+200ta(7_56) ranging from 8 to 38 repeats alleles. (ta)9 was the most prevalent allele both in normal individuals and cf patients with 30% and 23.5% frequencies respectively. all normal subjects and 97.5% of cf patients showed heterozyous genotype. the high heterozygosity of the two studied microsatellites witnesses the dynamism of such markers. high degree of heterozygosity of c.3499+200ta(7_56) and d7s523 make these markers, a very useful tool for prenatal diagnosis especially in iranian population.