Abstract
In a female infant with dysmorphic features, severe neurological defects, and congenital blindness, a positive urinary Bratton-Marshall test led to identification of a massive excretion of 5-amino-4-imidazolecarboxamide (AICA)-riboside, the dephosphorylated counterpart of AICAR (also termed "ZMP"), an intermediate of de novo purine biosynthesis. ZMP and its di- and triphosphate accumulated in the patient's erythrocytes. Incubation of her fibroblasts with AICA-riboside led to accumulation of AICAR, not observed in control cells, suggesting impairment of the final steps of purine biosynthesis, catalyzed by the bifunctional enzyme AICAR transformylase/IMP cyclohydrolase (ATIC). AICAR transformylase was profoundly deficient, whereas the IMP cyclohydrolase level was 40% of normal. Sequencing of ATIC showed a K426R change in the transformylase region in one allele and a frameshift in the other. Recombinant protein carrying mutation K426R completely lacks AICAR transformylase activity.
Publication types
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Case Reports
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Research Support, Non-U.S. Gov't
MeSH terms
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Aminoimidazole Carboxamide / analogs & derivatives*
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Aminoimidazole Carboxamide / metabolism*
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Blindness / congenital
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Child, Preschool
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Erythrocytes / metabolism
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Female
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Fibroblasts / drug effects
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Humans
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Hydroxymethyl and Formyl Transferases / deficiency
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Hydroxymethyl and Formyl Transferases / genetics*
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Metabolism, Inborn Errors / genetics*
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Molecular Sequence Data
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Mutation / genetics*
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Nucleotide Deaminases / genetics*
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Nucleotide Deaminases / metabolism
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Phosphoribosylaminoimidazolecarboxamide Formyltransferase
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Purines / biosynthesis*
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Recombinant Proteins / genetics
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Ribonucleotides / metabolism*
Substances
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Purines
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Recombinant Proteins
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Ribonucleotides
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Aminoimidazole Carboxamide
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Hydroxymethyl and Formyl Transferases
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Phosphoribosylaminoimidazolecarboxamide Formyltransferase
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Nucleotide Deaminases
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IMP cyclohydrolase
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AICA ribonucleotide
Associated data
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GENBANK/BC008879
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RefSeq/NT_005403