Figure 3: Validation of CFTR variants among family members by Sanger sequencing. (a) Chromatogram of CFTR variations showing the father and four patients (III:1, IV:2, IV:5, IV:7, and IV:13) were heterozygous (indicated by red arrows) for rs121909035 mutation, while the mother and normal sister (III:2 and IV:11) carried normal alleles (black arrows). (b) In rs35516286 variant, the father and two patients (III:1, IV:2, and IV:7) were normal, and the other participants carried heterozygous variation. (c) In the case of rs1800111, the mother and two patients (III:2, IV:2, and IV:7) carried heterozygous allele, while the father and the other offspring (III:1, IV:5, IV:11, and IV:13) were normal. Ref: reference; A: adenine; C: cytosine; G: guanine; T: thymine; CFTR: cystic fibrosis transmembrane conductance regulator; mut: mutant; het: heterozygous. IV:9 patient's DNA is not available, we assumed he would be in compound heterozygous state.