Characterization of the IVS17bTA microsatellite marker and six CTFR gene mutations in 21 Cuban families

Cystic fi brosis is an autosomal recessive disease. Its incidence in Cuba is 1 in 5000 live births. The molecular cause underlying this disease is related to mutations in the regulatory gene encoding the cystic fi brosis transmembrane regulator (CFTR). In this study, the techniques for the study of IVS17bTA microsatellite marker were standardized, and the most frequent mutations in the CFTR gene were also detected for 21 Cuban families. Polymerase chain reaction, agarose and polyacrylamide (plus silver staining) gel electrophoresis techniques were used for both, identifi cation of mutations and microsatellite standardization. Among the 22 Cuban patients, seven were found homozygous, four compound heterozygous and 11 with a single mutation so, 33 chromosomes were molecularly characterized for the 75 %. Twelve allelic variants were found for the IVS17bTA microsatellite; alleles 31 and 7 the most frequent ones. Alleles 31 and 46 were associated to the F508del and R334W mutations, respectively. Among the 21 families, 18 were completely informative for the IVS17bTA microsatellite marker, accounting for 85.7 %. This study helped to complete the diagnosis in those patients in which the responsible mutations in one or both chromosomes had not yet been identifi ed. Besides, we were also able to identify mutations associated with different alleles of the marker without gene sequencing, also helping to decrease the cost of screening.