The deoxyribonuclease I (DNase I) system was studied in 120 unrelated
Japanese patients with liver disease, malignant neoplasms, alimentary-
canal disease and inflammatory conditions with respect to the distribu
tion of phenotypes and gene frequencies in serum samples. In patients
with alimentary-canal disease a significant deficit of the DNase I phe
notype 1-2 was demonstrated, which suggests that heterozygosity may co
nfer protection against such disease. Furthermore, a significant assoc
iation between the DNase I phenotype 2 and liver disease was found. Th
e possible involvement of these phenotypes in the response to these di
seases would appear to merit further study.