Fragile X syndrome (FXS) is an inherited genetic disorder resulting in developmental delays and challenging behaviors. Reliable, accurate tests are available for carrier, prenatal, or newborn screening. Since genetic screening is not routinely offered, FXS is typically identified through behavioral observation. The variability and subtlety in the expression of FXS make early identification challenging. The article reviews the research and recommends a set of characteristics to enhance the identification process. While a checklist alone is unlikely to improve identification during the infant-toddler years, it may alert professionals to more obvious cases, help confirm parental and professional suspicions over several visits, and yield more fine-grained observations and precise comparisons.
