STXBP1 and Epileptic encephalopathy: In patients with epileptic encephalopathy and features of ASD, motor stereotypies are specifically noted in disorders involving the following genes: CDKL5 (hand flapping) [32], HCN1 [30], IQSEC2 (hand flapping) [33], MEF2C (hand wringing) [34], NRXN1 (body rocking) [35], PCDH19 (hand flapping, hand mouthing, and spinning) [36], SIK1 (hand flapping) [31], SLC35A2 (head and hand stereotypies) [37], SLC6A1 [29], and STXBP1 (hand flapping and stereotyped hand washing) [38, 39].