Adenylosuccinate Lyase Deficiency

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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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

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.
It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site www.rarediseases.org or email orphan@rarediseases.org
Last Updated: 10/8/2004
Copyright 2003, 2004 National Organization for Rare Disorders, Inc.

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