This implies (i) that normal total CPT activity in patients with muscle CPT II deficiency is not due to compensatory increase of CPT I activity and that (ii) the mutant CPT II is enzymatically active.
Retrospective analysis of patients with CPT II deficiency has made it possible to correlate the presence of disease-causing mutations in the CPT2 gene with residual CPT activity in muscle.
Although CPT deficiency can be classified into hepatic (CPT I) and muscular (CPT II) presentations, these data suggest that another symptomatology of CPT II deficiency with CNS involvement (brain type?) might exist.