The most common mutation is a homozygous loss of the phenylalanine residue at position 508 of the CFTR protein (Phe508del), occurring in ~70% of people with CF, with 85.8% of individuals harbouring this mutation on one allele (https://www.cff.org/sites/default/files/2021-11/Patient-Registry-Annual-Data-Report.pdf, accessed on 12 February 2022). This evidence concerns the gene CFTR and cystic fibrosis.