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Methylmalonic acidaemia due to mutase apoenzyme defect: Responsive to vitamin B 12 in intact fibroblasts but not in vivo
Author(s) -
Baumgartner R.,
Giardini O.,
Cantani A.,
Sabetta G.,
Castro M.
Publication year - 1982
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01800166
Subject(s) - mutase , methylmalonic acidemia , methylmalonic acid , propionic acidemia , propionate , enzyme , in vivo , medicine , endocrinology , vitamin b12 , cobalamin , biochemistry , biology , genetics
Congenital methylmalonic acidaemia (MMA‐aemia) was diagnosed in an 8‐month‐old girl who presented with severe metabolic acidosis, hypoglycaemia and hyperglycinaemia. Vomiting, failure to thrive and apathy first appeared when breast feeding was replaced by a cows' milk formula at the age of 3 months. The patient, unresponsive to OH‐Cbl therapy, was successfully treated with dietary protein restriction and with Shohl's solution. Aged 4 years 9 months, she is in good health. Studies in cultured fibroblasts revealed a defect of the MMA‐CoA mutase apoenzyme. Mutase activity in cell extracts was barely detectable both with and without added coenzyme (Ado‐Cbl). Addition of OH‐Cbl to the culture medium improved overall propionate metabolism in intact fibroblasts but had no effect on mutase activity in cell extracts. These observations point to the presence of a very labile mutant enzyme, suggesting that the patient reported here may be suffering from yet another variant of MMA‐aemia.