DIAGNOSIS OF COMPLEX-I DEFICIENCY IN PATIENTS WITH LACTIC ACIDEMIA USING SKIN FIBROBLAST-CULTURES

The requirement for a rapid and easy method of preparing mitochondrial fractions from cultured skin fibroblasts led us to compare the result s obtained from such a preparation with the more traditional methods o f cellular fractionation. Values for NADH-cytochrome c reductase (rote none sensitive) were compared for a series of three controls and nine patients with complex I(NADH-coenzyme Q reductase deficiency). Values obtained for deficient cell lines varied from 19 to 64% of the control values for the long mitochondrial preparation method and from 34 to 7 0% of control for the rapid preparation. Mean values were statisticall y significantly different from the lowest control cell line (P < 0.01) in all cases. The specific activity on the basis of activity per mill igram of mitochondrial protein and of activity per unit of citrate syn thase activity was lower in the rapid preparation of mitochondria by s ome 41%, indicating a lesser degree of mitochondrial purification. How ever, the overall result showed that this type of rapid preparation, w hich uses four 9-cm petri dishes of cultured cells, can be used to dia gnose mitochondrial complex I deficiency. This method will find genera l use in the measurement of either mitochondrial enzymes of low specif ic activity or mitochondrial enzymes whose measurement is made difficu lt by contaminating nonmitochondrial enzymes. (C) 1996 Academic Press, Inc.