Multiple occurrence of macro creatine kinase in one family.

We measured creatine kinase (CK, EC 2.7.3.2), CK-MB isoenzyme activity and mass concentration, and distribution of CK isoenzymes (by electrophoresis) in serum from five members of one family. The mother and two young children showed CK-IgG complexes in their sera. The concentration of the CK-IgG complexes in the children decreased over time, suggesting that the complex involved maternal IgG and had been transferred across the placenta from the mother to her children.