Fragile X chromosome

Fragile X chromosomes are characterized by satellite regions, visible at the bottom ends of the long arms of metaphase X chromosomes in the scanning electron micrograph and the Giemsa-stained photo (inset, upper right). The constrictions are due to a long series of CGG triplet repeats. Fragile X is associated with Martin-Bell Syndrome, the most common form of inherited predisposition to mental retardation.

[For further information, see http://www.fragilex.org/index.htm]