Screening for cystic fibrosis [editorial].

Cystic fibrosis (mucoviscidosis) is the most common potentially lethal autosomal recessive disease 
in Caucasian peoples. Despite much research and several promising leads there 
is no completely reliable test for detecting heterozygotes, nor a test 
for the identification of the affected homozygous fetus in utero. Attention 
is being focused on the value and the means of screening 
newborn infants. Pilot studies carried out in the past six years 
have indicated two main possibilities. Firstly, the examination of meconium for 
excess albumin, refined to include immunoelectrophoretic estimation of the albumin alpha-1 
antitrypsin ratio, disaccharidases, and lysosomal enzymes. A second approach is based 
on the work with a chloride-sensitive electrode, which has been modified 
recently to give greater precision in measurement of neonatal sweat electrolytes. 
While the tests available are reasonably accurate, collaborative trials and respiratory 
could improve their efficiency still further. Nevertheless, any screening test is 
presumptive only, and there must be an adequate back-up service with 
a specific validated diagnostic test. 