| Description | Succinylaminoimidazole carboxamide riboside, also known as SAICAr, is the riboside form of the better known compound SAICAR (the ribotide). Ribosides chemically resemble ribotides except they do not contain a phosphate group. The appearance of succinylaminoimidazolecarboxamide riboside (SAICAriboside) and succinyladenosine (S-Ado) in cerebrospinal fluid, in urine, and, to a lesser extent, in plasma is characteristic of a heritable deficiency known as adenylosuccinate lyase deficiency (ADSL). Adenylosuccinate lyase deficiency is responsible for a range of symptoms that involve psychomotor retardation, often accompanied by epileptic seizures, and autistic features. In adenylosuccinate lyase deficiency it is believed that the buildup of SAICAr causes neurotoxic effects. In the severely affected individuals, the concentration levels of SAICAr and S-Ado are comparable, whereas in people with milder forms of the disease, the concentration of S-Ado is more than double that of those more severely affected, while SAICAr concentration levels remain comparable. Therefore, when present in sufficiently high levels, SAICAr can act as a metabotoxin and an acidogen. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart, liver, and kidney abnormalities, seizures, coma, and possibly death. These are also the characteristic symptoms of untreated adenylosuccinate lyase deficiency. Many affected children with organic acidemias experience intellectual disability or delayed development. |
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| InChI Identifier | InChI=1S/C13H18N4O9/c14-10-7(11(23)16-4(13(24)25)1-6(19)20)15-3-17(10)12-9(22)8(21)5(2-18)26-12/h3-5,8-9,12,18,21-22H,1-2,14H2,(H,16,23)(H,19,20)(H,24,25)/t4-,5+,8+,9+,12+/m0/s1 |
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