Cystic fibrosis heterozygote detection: a family study

Family studies have been done to determine if the phenotypes described for the cystic fibrosis (CF) cultured cell reliably detected the CF gene. Two culture phenotypes were studied in culture derived from consecutive generations in four CF families: (1) cystic fibrosis factor (CFF) in the medium of short-term white blood cell cultures assayed by a modified oyster ciliary test and (2) the three characteristics of cultured skin fibroblasts (metachromasia without alcianophilia at 0.3 M MgCl2, CFF in the culture medium and metabolic cooperation with normal fibroblasts). As CF is an autosomal recessive disorder, the family offered a test unit for determining the specificity of these cell phenotypes for the CF gene. On the basis of detecting the CF culture phenotypes in the homozygote and obligatory heterozygotes, the parents, and their segregation in consecutive generations, detection of the CF gene was not possible in the white blood cell cultures, but was possible in the skin fibroblast cultures.