Checklist assessments of FMR1 gene mutation phenotypes.

Background: Fragile X Syndrome (FXS) caused by the mutation of the FMR1 gene, is the most common inherited cause of intellectual disability, autism, and other psychoneurological disorders. Timely identification of young children with social or emotional challenges is urged in that emotional and social problems are often overlooked until problems reach serious magnitudes. Reliable methods of screening children at an earlier age are crucial to early intervention.