ATYPICAL METHYLMALONIC ACIDURIA WITH PROGRESSIVE ENCEPHALOPATHY, MICROCEPHALY AND CATARACT IN 2 SIBLINGS - A NEW RECESSIVE SYNDROME

Two siblings with atypical methylmalonic aciduria and progressive ence phalopathy are reported. Initial symptoms were failure to thrive and g rowth retardation from the first year of life, progressing to severe m ental retardation, microcephaly, dystonia, spasticity and cataracts. T he amount of methylmalonic acid excreted in the urine was substantiall y lower than in classical methylmalonic acidemia and was not reduced b y vitamin B-12 therapy. The activity of methylmalonyl-CoA mutase and t he overall assay of propionic acid metabolism in cultured fibroblasts were normal. The primary defect in this probably new autosomal recessi ve disorder associated with methylmalonic aciduria is currently not kn own.