Fragile X Syndrome is a genetic condition causing intellectual disability, behavioral and learning challenges, and various physical characteristics. It is also the most common single-gene cause of autism worldwide. While many people are familiar with autism, they are not as familiar with the specific conditions that lead to the disorder, such as Fragile X Syndrome. Questions such as this are not meant to disqualify a person from a job if they are unfamiliar with a diagnosis. Most interviewers use these questions to introduce candidates to the specialty areas their facility offers. If you know the syndrome, share it. If you do not, state that you are unfamiliar, but do so with interest, which is what the interviewer is looking for.