ERG can be explored in individuals with other rare genetic BK channelopathies, including mutations in KCNMA1, KCNMB4, CRBN, and the FMR1 R138Q variant (mutation at the site of FMRP binding to BK channel), to assess whether similar retinal dysfunction patterns to FXS are observed. This evidence concerns the gene KCNMB4 and fragile X syndrome.