As for working memory, those male patients with FXTAS performed significantly worse on the WAIS–III Working Memory Index (Grigsby et al., 2008) and WAIS-III Letter-Number Sequencing (Brega et al., 2008) compared to the controls with normal FMR1 alleles. This evidence concerns the gene FMR1 and fragile X-associated tremor/ataxia syndrome.