Identification of novel mutations in Arabs with cystic fibrosis and their impact on the cystic fibrosis transmembrane regulator mutation detection rate in Arab populations.
UNLABELLED: The cystic fibrosis transmembrane regulator (CFTR) gene in Arab patients with cystic fibrosis (CF) (sweat chloride > 60 mmol/l) from 61 unrelated families was screened for mutations in exons 3, 4, 5, 7, 10, 11, 16 and 19 and for mutations W1282X, N1303K and 3,849 + 10kbC --> T. Eight novel mutations were identified. These are: in exon 4: a) 425del42 (an in-frame 42 bp deletion that removes 14 amino acids and causes Gln98 --> His at the point of deletion), b) 475G --> T (Glu115 --> Stop) and c) 548A --> T (His139 --> Leu); in intron 5,711 + 1G --> A (splice site mutation); in exon 10, 1548delG (deletion of a "G" nucleotide causing a frameshift mutation that alters the amino acid sequence at residue 473 and results in translation termination at residue 526); in exon 11, a) 1729T --> C (Ph533E --> Leu) and b) 1,811 + 2 (splice site mutation) and finally in exon 19,3361A --> T (Lys1177 --> Stop). All mutations were detected by heteroduplex analysis and identified by sequencing. Of more than 850 known CFTR mutations, only 9 were encountered. The comparative frequencies of the most common mutations are: 1548delG> 1123V = deltaF508 = 3,120 + 1G --> A > H139L. Screening for these five mutations identifies 60% of the CF alleles in Arab populations. The novel mutation 1548delG is the most frequent (17%) among Arabs. CONCLUSION: Novel Arab-specific mutations were identified in the CFTR gene underlying cystic fibrosis. As a result of this study, the CFTR mutation detection rate among Arabs with cystic fibrosis is now comparable to that of other populations.