Methemoglobinemia and mental retardation associated with NADH-diaphorase deficiency was found in a 2-year-old girl of Spanish origin. She showed no NADH-diaphorase activity in either erythrocytes or leukocytes, but electrophoretic studies of the hemolysate showed traces of an enzyme with normal mobility. Cytochrome b5 reductase activity was also found to be absent in the leukocytes of the propositus. Intermediate NADH-diaphorase activity was found in erythrocytes and leukocytes in her parents and her sister in accordance with the autoso-mal recessive mode of inheritance of this enzymopathy. The relationship between a generalized cytochrome b5 reductase deficiency and the progressive neurological involvement in our patient is discussed briefly.
The activities of the key glycolytic enzymes phosphofructokinase (PFK), pyruvate kinase (PK) and hexokinase in addition to adenosine deaminase, purine nucleoside phosphorylase (PNP) and lactate dehy-drogenase (LDH) have been measured in lymphocytes from 39 cases with B-chronic lymphocytic leukaemia (B-CLL). According to the percentage of circulating large non-granular atypical lymphocytes (AL) the B-CLL cases were classified as: typical ( < 10% of AL; 28 cases) and atypical (10-25% AL; 11 cases). In both groups the median lymphocyte volume (MLV) was assessed and correlated with the correspondent enzyme activities.The MLV of B-CLL lymphocytes was significantly (p < 0.001) decreased (149.9 ± 19.4 fl) as compared to normal B lymphocytes (175.1 + 14.5 fl) and it was significantly (p < 0.001) lower in typical B-CLL (141.8 ± 12.2 fl) than in atypical B-CLL (172.0 ± 17.2 fl). Furthermore, in patients with typical B-CLL, all enzyme activities when expressed as U/109 cells were, with the exception of PFK, significantly decreased compared to normal B lymphocytes. However, when the results were expressed as U/ml cells, only PK, PNP and LDH remained significantly low.These findings demonstrate that the determination of MLV in addition to morphology may be a useful tool to distinguish the two previously described morphological B-CLL variants (typical and atypical) and that these two different B-CLL groups are also distinguishable on the basis of three enzyme activities, PK, PNP and LDH which have been shown to be less dependent on cell size than the other enzymes, also studied here.
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