Erythroenzymopathies: Mechanisms of isozyme switches and clarification of genetic abnormalities

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We discovered 7 new cases of glucose 6-phosphate dehydrogenase deficiency and 3 new cased of pyruvate kinase (PK) deficiency after the survey of patients showing non-spherocytic hemolytic anemia due to unknown causes. In addition to these works, we could clone the cDNA for liver-type PK and assign its chromosomal locus as a first step for the clarification of molecular anomalies. PK has four isozymes (L, R, <M_1> , <M_2> ) that are encoded mainly by two different genes. We isolated a cDNA clone from a Japanese adult liver <lambda> gt10 cDNA library by using a rat liver (L)-type PK cDNA probe. One positively hybridizing clone, hlPK-1, which contained a 1,049-base pair cDNA insert, was subjected to DNA sequence analysis.Comparisons of the sequence data with the rat PK cDNAs indicated that the cDNA encoded information for the carboxyl terminal 105 amino acids of a human L-type PK and a 3'untranslated region of 734 nucleotides. Furthermore, the karyotype analysis of several human-mouse hybrid cells and Southern blot analysis of DNAs of the hybrids with a hlPK-1 indicated that the human L-type PK gene is located on chromosome 1.