FMR1 and fragile X syndrome: This result can be justified by the presence of an extra X chromosome without FMR1 expansion for females.10 Because the FMR1 gene is essential for cognitive development, it has been shown that FXS patients commonly experience several mental disorders.34 This evidence is consistent with our results of enrichment of direct comorbidities in males such as “Mild mental retardation” (F70), “Moderate mental retardation” (F71), “Unspecified mental retardation” (F79), and “Pervasive developmental disorders” (F84).