Molecular Diagnosis Cystic Fibrosis Patients from South Moravia Region
Cystic fibrosis (CF) , the most common serious recessive genetic disorder in Caucasians, is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). The frequency of the disease varies approximately 1 in 2500 live births. The CFTR gene , located on 7q31.1 chromosome (Riordan J.R. et al. 1989), is 250 kb long and contains 27 exons, its mRNA transcript was deduced to be about 6,5kb, encoding polypeptide of 1,480 amino acids. Since the discovery of the CFTR gene and its major mutation, Delta F508, in 1989, over 800 mutations of the gene have been described worldwide ( ECCACF 1999)) and for the Czech population ( Macek et al. 1999).
Although the basic defect in CF is not fully understood, the CFTR protein has been established as a cyclic adenosine monophosphate-regulated chloride channel which is defective, reduced or absent in CF patients. The major symptoms of the CF disease include malabsorption, steatorrhoea and recurrent chest infections with increased excretion of salt in the sweat.
During 1993 to 1999 period the identification of CF patient's mutations was provided for a molecular confirmation of the diagnosis of cystic fibrosis. The 84 chromosomes from the group of 42 CF patients ? children were examined on the molecular level (Schwarz M.J. 1998) and the genotypes were determined by methods of direct mutational analyses and by screening methods single strand conformation polymorphism (SSCP), denaturing gradient gel electrophoresis (DGGE) (Costes B. et al. 1993) and heteroduplex analyse (HA). It was found 72% of CF alleles represented by Delta F508 mutation and 7% of CF chromosomes with G542X mutation. Other CF mutations ( G551D, N1303K, 3849+10 kb Cto T ) were less frequent. The DGGE method determined mutational positive exons 6a, 9, 12, 14, 23 in the case of seven CF patients with compound genotypes.
Screening methods were also used for testing of CF carrier status in the group of gamet donors to reduce the risk of CF. In this group, nucleotide change A> N in noncoding tract of intron 11 was firstly described. All carriers of CF alleles were excluded from the donorship.
Searching of correlation between position mutation on the CF gene, pathological function of CFTR protein and clinical state of CF patients is in progress.
The work was supported by ECCACF ( C. Cazaneuve).
(1) Riordan J.R. et al. (1989)Science, 245, 1066 ?73
Valaskova I., Kadlecova J. Ravcukova B., Cazeneuve C1Holcikova A2, Gaillyova R. and Vojtiskova M.
Department of Human Genetics
1Service de Biochemie,