Thumb aplasia together with epilepsy has not been reported; however, thumb hypoplasia or thumb deformities together with epilepsy have been reported in carriers of microdeletions, encompassing the loci of the SCN3A, SCN2A, TTC21B, SCN1A, and SCN9A genes [4], or of point mutations in KCNH1 that manifest phenotypically as Zimmermann-Laband syndrome or Temple-Baraitser syndrome [5]. The gene discussed is TTC21B; the disease is epilepsy.