The "mild" gene variant, p.Arg117His in cystic fibrosis (CF) results in highly variable phenotypes ranging from male infertility to severe lung disease.
Patients with two identified CFTR mutations which include the R117H/7T anomaly should be followed up routinely as they remain susceptible to severe lung disease.
The 5T allele in intron 8 (IVS8) causes abnormal splicing in the CFTR gene, and is associated with lung disease when it occurs in cis with a missense mutation in the CFTR gene, R117H.