Adenylosuccinate Lyase Deficiency

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Adenylosuccinate Lyase Deficiency is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

Adenylosuccinate lyase deficiency (ASLD) is a rare, inherited metabolic disorder due to a lack of the enzyme adenylosuccinate lyase (ASL). The defect is characterized by the appearance of two unusual chemicals, succinylaminoimidazole carboxamide riboside (SAICA riboside) and succinyladenosine, in cerebrospinal fluid, in urine and, to a much smaller extent, in plasma. These compounds, which are never found in healthy individuals, are formed from the two natural compounds acted upon by the enzyme. The symptoms and the physical findings associated with ASLD vary greatly from case to case. As a rule, patients with ASLD present with a mix of neurological symptoms that usually will include some of the following: psychomotor retardation, autistic features, epilepsy, axial hypotonia with peripheral hypertonia, muscle wasting, and secondary feeding problems. Although abnormal physical features (dysmorphism) are not common, when they do occur they may include severe growth failure, small head circumference, brachycephaly, flat occiput, prominent metopic suture, intermittent divergent strabismus, small nose with anteverted nostrils, long and smooth philtrum, thin upper lip, and low set ears.

Adenylosuccinate lyase deficiency is categorized as a disorder of the manufacture of purine nucleotides from scratch (biosynthesis) in the body. Purine nucleotides play vital roles in the cells, particularly in the process of building up or breaking down complex body chemicals (intermediary metabolism) and in energy-transforming reactions. Moreover, they serve as building blocks of nucleic acids and thus participate in molecular mechanisms by which genetic information is stored. Just how the genetic and molecular mechanisms interact to generate the symptoms of ASLD is still debated.

Supporting Organizations

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311

For a Complete Report

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Last Updated:  9/9/2010
Copyright  2010 National Organization for Rare Disorders, Inc.