A RARE DIAGNOSIS (ADENYLOSUCCINATE LYASE DEFICIENCY)

What is Adenylosuccinate lyase deficiency? Hayden was diangosed with ASLD at three months old. Many people have never heard of adenylosuccinate lyase deficiency. The deficiency is responsible for a range of symptoms that involve psychomotor retardation, often accompanied by epileptic seizures, and autistic features. Most patients suffer from moderate to severe retardation, while rare patients display only mild psychomotor retardation. Two common theories were proposed to account for these effects. The first is that they result from decreased concentrations of purine nucleotides needed for purine biosynthesis. Decreased concentrations, however, could not be found in various tissues taken from ASL-deficient patients, probably because purines are furnished via the purine salvage pathway and some residual activity of ASL. The second is the buildup of accumulating succinylpurines causes neurotoxic effects. In the severely affected patients, the concentration levels of SAICA riboside and S-Ado are comparable, whereas in patients with milder forms of the disease, the ratio of S-Ado is more than double that of those more severely affected, while SAICA riboside concentration levels remain comparable. This suggests SAICA riboside is the major contributor, while S-Ado may protect against SAICA riboside’s toxic effects. As of 2004, about 60 patients had been diagnosed with ASL deficiency, but many more are thought to be undiagnosed, due to the heterogeneity of the disease and a paucity of general screening. Patients have been diagnosed from a number of areas around the world, although a large number of them are from the Low Countries. ASL deficiency rose to prominence in the well documented case of Michael Dignan, a developmentally challenged youth. There is yet no cure for this deficiency. For more information search the following: http://en.wikipedia.org/wiki/Adenylosuccinate_lyase_deficiency