Adenylosuccinate Lyase Deficiency

National Organization for Rare Disorders, Inc.

Important
It is possible that the main title of the report Adenylosuccinate Lyase Deficiency is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • Adenylosuccinase Deficiency
  • Succinylpurinemic Autism

Disorder Subdivisions

  • Adenylosuccinate Lyase Deficiency Type I
  • Adenylosuccinate Lyase Deficiency Type II
  • Adenylosuccinate Lyase Deficiency Type III
  • Adenylosuccinate Lyase Deficiency Type IV

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.
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Resources

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
TDD: (888)205-3223
Email: ordr@od.nih.gov
Internet: http://rarediseases.info.nih.gov/Default.aspx

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

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