Identification of cystic fibrosis homozygotes and heterozygotes by isoelectric focusing of serum proteins.

Screening of 44 cystic fibrosis homozygotes, 17 heterozygotes and 36 normal controls, by identification of cystic fibrosis protein (CFP), was performed on sera using an improved isoelectric focusing technique. CFP was observed in 91% of homozygotes, 88% of heterozygotes and 8% of normal controls tested. Partial purification of CFP by chromatofocussing indicates that CFP has a molecular weight of about 52,000 u. It is speculated that CFP is a normal serum protein that exhibits a quantitative difference in concentration between CF homozygotes, heterozygotes and normals.