Pyruvate carboxylase deficiencies: complementation studies between "French" and "American" phenotypes in cultured fibroblasts.

Pyruvate carboxylase (PC) deficiencies (McKusick 26615) are heterogeneous clinically and biochemically. We performed a complementation study with fibroblast strains from seven patients, (four patients with "French" phenotype, two patients with "American" phenotype, one patient with biotin responsive multiple carboxylase deficiency, MCD). The six isolated pyruvate carboxylase mutants (two cross-reacting material CRM -ve and four CRM +ve) failed to complement each other, but did complement a form of biotin responsive MCD.