Sixty years of X-linked mental retardation: A historical footnote

X-linked mental retardation (XLMR) is a most exciting field of modern medic al genetics. It made spectacular advances over the last twenty years, after the advent of molecular genetics. The discovery of the FMR1 gene unraveled the cause of the most common form of heritable mental retardation and prov ided the prototype of dynamic mutations. New genes continue to be mapped to the X chromosome and more and more are being cloned and characterized, cla rifying the nosology of XLMR and, more importantly, adding to our understan ding of the mechanisms of intellectual development, normal and abnormal. Lo oking back to a more or less recent past may provide clues for future disco overies. Am. J. Med. Genet. (Semin. Med. Genet.) 97:228-233, 2000. (C) 2000 Wiley-Liss, Inc.