Epidemiology of alpha 1-antitrypsin deficiency in the Netherlands.

During a 3-year period, newborns in the eastern part of the Netherlands were investigated for alpha 1-antitrypsin deficiency. Electroimmunoassay was used for screening, followed by Pi typing in suspected cases. In all 95 033 newborns were screened, and a mean frequency of deficiency (phenotypes Pi Z, Pi SZ, and Pi S) of 8.00 in 10 000 was found. The distribution of deficient Pi types over the area was remarkably uneven, Pi type Z being more predominant north and Pi type S south of the Rhine. Cluster areas of alpha 1-antitrypsin deficiency, with frequencies of up to 59.6 in 10 000 live births, occurred mainly in small rural communities. In urbanized areas the frequency of deficiency was lower than the mean.