A decrease in cerebellar volume has also been reported in multiple genetic pathologies related to ASD, including fragile X syndrome (FXS) [70,71], Rett syndrome [70,71,72], the Phelan–McDermid syndrome, including Shank3 deletion [73,74] (SH3 and multiple ankyrin repeat domains 2), and NLGN4 (Neurologin-4) associated non-syndromic X-linked ASD [46]. The gene discussed is SHANK3; the disease is fragile X syndrome.