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La piruvato carboxilasa (PC), una enzima mitocondrial, cataliza la conversión de piruvato, producto final de la glucólisis, en oxaloacetato, un intermediario del ciclo del ácido tricarboxílico. El déficit de piruvato carboxilasa, un trastorno raro, se manifiesta en tres fenotipos clínicos y bioquímicos: tipo de inicio neonatal (tipo A), tipo de inicio infantil (tipo B) y un tipo benigno (tipo C).

Pyruvate carboxylase, a mitochondrial enzyme, catalyses the conversion of glycolytic end-product pyruvate to tricarboxylic acid cycle intermediate, oxaloacetate. Rare pyruvate carboxylase deficiency manifests in three clinical and biochemical phenotypes: neonatal onset type A, infantile onset type B and a benign C type. The objective of this case series is to expand the knowledge of overlapping clinical and biochemical phenotypes of pyruvate carboxylase deficiency.

Fumaric aciduria resulting from fumarate hydratase deficiency is a rare inherited disorder of the Krebs tricarboxylic acid cycle that is characterized by neurologic manifestations, a spectrum of brain abnormalities, and the excretion of fumaric acid in urine. We describe a 3 year old Sri Lankan boy who was referred at age 10 months with poor weight gain and hypotonia for further laboratory investigations. In addition to global developmental delay, there were noticeable dysmorphic features with a prominent forehead, low-set ears, micrognathia, and hypertelorism with persistent neutropenia. Urine organic acid assay revealed a massive elevation of fumaric acid on 2 occasions. Molecular analysis revealed a homozygous likely pathogenic missense variant, NM000143.3:c.1048C>T p. (Arg350Trp), in the FH gene, confirming the biochemical diagnosis. Our patient was the first patient in Sri Lanka molecularly diagnosed with fumaric aciduria. This case study highlights the importance of performing organic acid assays in children presenting with neurologic manifestations especially when these are suspected to have a metabolic basis. [ABSTRACT FROM AUTHOR]

A correction is presented to the article "Urine Organic Acid Analysis: Key Diagnostic Test for Fumaric Aciduria in a Sri Lankan Child."