- Diagnosis of CF based on the following: sweat chloride > 60 mEq/L and/or genotype with 2 identifiable mutations consistent with CF; (ΔF508 homozygote, or ΔF508 heterozygote with a second allele known to cause the disease, or two alleles known to cause a class I, II, or III mutation) and one or more clinical features consistent with CF.