Classic Cystic Fibrosis Presentation in Two Middle Eastern Siblings with a rare CFTR mutation (c.80G>T)

Cystic fibrosis (CF) is a common autosomal recessive disorder which is mainly found in Caucasians but has also been reported in Asian populations. CF is primarily caused by mutations in the CFTR gene which regulates the transport of chloride ions across the cell membrane. We describe the cases of two siblings with CF diagnosed with the rare missense mutation c.80G>T, which has only been referenced once in the literature and shows a possible association with classical form of CF. LEARNING POINTS: c.80G>T is a very rare CFTR missense mutation which has not been known to be a disease-causing alteration. The mutation causes an amino acid switch from glycine to valine at position 27 in exon 2, resulting in the production of defective CFTR protein. In the homozygous state, c.80G>T seems to be associated with the classic CF phenotype.