Lactate Dehydrogenase B (LDHB)

LDHB and peptidase B are linked (Santachiara et al., 1970) and both loci are on chromosome 12 (Chen et al., 1973). Kitamura et al. (1971) reported the first case of a complete deficiency of lactate dehydrogenase subunit H(B) in serum, saliva and erythrocytes of a 64-year-old male with mild diabetes. Study made on family members revealed low LDH activity in their serum also linked with decreased relative activity of the H4(B4) fraction. Based on the comparison of the calculated ratio of H to M subunits in normal and affected family members, it was hypothesized that the proband is homozygous while the abnormal family members are heterozygous, assuming a single gene is involved. Red cell metabolism in the proband was studied by Miwa et al. (1971); neither reticulocytosis nor hemolytic anemia was present.