Creatine kinase in human erythrocytes: a newly detected genetic anomaly.

In a family of Italian origin, we found four members with a considerable activity of creatine kinase inside their erythrocytes. All other clinical and hematological findings were normal. The enzyme anomaly seems to be inherited in the autosomal mode. The creatine kinase CK) activity in freshly drawn blood was about 12 U/g Hb. The activity was higher in young red cells than in older ones. Studies with specific antibodies against human CK isoenzymes revealed the CK activity in the probands' red cells to be due to about 90% to the BB-isoenzyme normally found in brain and nerve tissue. The presence of CK in the erythrocytes does not seem to have any consequences for the energy metabolism of the cells. Creatine concentration was slightly elevated, but creatine phosphate could not be detected.