Carrier Detection of Pyruvate Carboxylase Deficiency in Fibroblasts and Lymphocytes

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Abstract
Summary: Pyruvate carboxylase (E.C. 6.4.1.1) activity was determined in the circulating peripheral lymphocytes and cultured skin fibroblasts from the family of a patient with hepatic, cerebral, renal cortical, leukocyte, and fibroblast pyruvate carboxylase deficiency (PCPortland deficiency). Lymphocyte activities were: mother, 33–39%; father, 11–29%; brother, 82–103%; and sister, 38–48% of the lowest normal. Fibroblasts from the patient's mother and father had 42 and 34%, respectively, of the activity of the lowest normal. These data demonstrate that the disease is inherited in an autosomal recessive manner and that lymphocytes and fibroblasts can be used to detect carriers. Neither pyruvate carboxylase nor mitochondrial PEPCK activity in lymphocytes was increased by a 21-hr fast. Speculation: The demonstration that carriers of pyruvate carboxylase deficiency can be detected with a venous blood sample may allow, with the use of extensive family studies, the assignment of this enzyme to a chromosomal linkage group.