Suggest Preliminary Test To Detect Adenylosuccinate Lyase Deficiency

My son is 3 months old and has undergone countless metabolic and genetic tests to try to determine what is causing him to have seizures. Recently his uric acid level came back abnormal and through my research I have come across Adenylosuccinate Lyase Deficiency. I understand that this is very rare, but I am wondering what preliminary tests would raise suspicion towards this deficiency.