Overview of repeats
CGG repeat expansions in the 5 UTR of DIP2B gene have been associated with FRA12A mental retardation (MRFRA12A). Research by Winnepenninckx et al. (2007) determined the repeat length in the control group to be between 6 and 23 repeats. In the individuals, who cytogenetically express fragile site (FRA12A) were found to have repeat expansions. In unaffected individuals, one allele was found to be 417-617 bp (~139-206 repeats), but in affected ones it was over 817 bp, corresponding to at least ~272 repeats (Winnepenninckx et al., 2007).