THE MOLECULAR-BASIS FOR GENETIC-POLYMORPHISM OF HUMAN DEOXYRIBONUCLEASE-I - IDENTIFICATION OF THE NUCLEOTIDE SUBSTITUTION THAT GENERATES THE 4TH ALLELE

In addition to the three alleles commonly responsible for the protein polymorphism of human deoxyribonuclease I, a mutation encoded by a fou rth allele, DNASE14, was detected by isoelectric focusing. All 8 exon s covering the entire open reading frame of the human DNase I gene wer e amplified by the polymerase chain reaction and subjected to direct s equencing. Only one nucleotide substitution, a C-to-G transition (CAG- -> GAG), in the codon for amino acid 9 of the mature enzyme was found. This substitution resulted in the replacement of Gin with Glu (Q9E).