Characterization of the frequency of delta F508 mutation and CF haplotypes in Swedish families

Sirs, The distribution of the haplotype (2:l) defined by the two CF-linked markers KM19:XV-2c has been reported to be between 70 and 90% in the European population (Estivill et al. 1987, 1988). Identification and characterization of one mutation causal of CF, delta F508, have made it possible to analyse for the presence of this in affected families (Kerem et al. 1989). This prompted us to investigate a sample of patients from Sweden for the presence of the delta F508 mutation in relation to haplotyping with the CF-linked markers KM19 and xv-2c. A total of 100 non-related CF-patients, representing approximately one third of the Swedish material, have been analysed in the present study, In addition, the distribution of haplotypes on CFchromosomes was investigated in 37 of these families. Blood samples were obtained from the parents and the children. DNA was isolated according to standard procedures and analysed with two CF-linked RFLPs, KM19 and XV-2c. The probeienzyme combination used was KM 19/PstI and XV-2c/TaqI. Oligonucleotide primers sequences and polymerase chain reaction (PCR) conditions were used to detect delta F508. The amplified products were analysed on 12% polyacrylamide gels and stained with ethidium bromide, as described (Rommens et al. 1990). The distribution of chromosomes with and without the mutation and the corresponding genotype are summarized in Table 1. Among the 200 CFchromosomes analysed for delta F508,120 carried the mutation. Hence, the frequency of the mutation on CFchromosomes in our material was