What is the karyotype for fragile X?

The karyotype for fragile X syndrome typically shows a normal chromosomal structure, but it is characterized by a mutation in the FMR1 gene located on the X chromosome. This mutation involves the expansion of CGG repeats, often exceeding 200 repeats, leading to a fragile site on the X chromosome that can appear as a constriction or gap during chromosomal analysis. The presence of this fragile site is associated with the developmental and cognitive features of fragile X syndrome.