PDCD2 and cerebellar ataxia: The CAG repeat expansion in the N-terminal domain ofTBPcauses late-onset spinocerebellar ataxia.33One patient analyzed by BAC clone FISH showed a smaller terminal deletion of approximately 400 kb involving only thePSMB1,PDCD2,andTBPgenes.4The study of heterozygous TBP mice suggested thatTBPis potentially involved in cognitive development.7A functional study noted that the silencing ofERMARDin the developing rat neocortex produced periventricular nodular heterotopia.14These results implied modifying effects from theTBPandERMARDgenes for the 6q terminal deletion syndrome.