Genetic polymorphism of human deoxyribonuclease II (DNase II): low activity levels in urine and leukocytes are due to an autosomal recessive allele

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Abstract
Summary: The objectives of this study were to elucidate the genetic basis of human deoxyribonuclease II (DNase II) and to evaluate its usefulness as a genetic and/or diagnostic marker. We have devised a novel, specific and highly sensitive assay method for the urinary and leukocytic enzymes (Yasuda et al. 1991). The distribution of the activities of both enzymes displayed clear‐cut bimodality and the Japanese study population could be classified into two distinct types, namely low‐activity (DNASE2 L) and high‐activity (DNASE2 H), which indicates the existence of a genetic polymorphism in the activity levels of urinary and leukocytic DNase Us. Close correlations between the leukocytic and urinary enzyme activity levels from the same individuals were observed and the types in the leukocyte samples agreed with the types found in the corresponding urine samples. In a population study of 528 unrelated Japanese individuals, the gene frequencies of the low activity (DNASE2*L) and the high activity (DNASE2*H) alleles were calculated to be 0·632 and 0·368, respectively. The sex and age of individuals did not affect the distribution of DNase II activity levels. The family study results were compatible with the model that the low activity type is due to an autosomal recessive gene, which indicates that DNASE2 L represents homozygosity for DNASE2*L and DNASE2 H corresponds to homozygosity for DNASE2*H and heterozygosity for DNASE2*L and DNASE2*H.