Furthermore, heterozygous mutations in IMPDH2 have recently been associated with neurodevelopmental disorders and mutations in IMPDH1 lead to common retinal degenerative disorders (i.e., retinitis pigmentosa and leber congenital amaurosis) (Bowne et al, 2002; Kennan et al, 2002). This evidence concerns the gene IMPDH2 and neurodevelopmental disorder.