PSAP and hyperinsulinemic hypoglycemia, familial, 4: Of the single saposin disorders, saposin A deficiency is the most severe and results in death at 8 months old ((Spiegel et al., 2005); OMIM #611722), whereas the mildest of the saposin C mutations cause non-neuronopathic disorders with relatively mild symptoms until the fourth decade of life ((Tylki-Szymanska et al., 2007); OMIM #610539).