http://www.nlm.nih.gov/mesh/jablonski/syndrome_db.html

It includes 700 of approximately 1600 to 2000 syndromes in which multiple congenital anomalies are associated with mental retardation, also includes chromosomal aberrations and X-linked mental retardation, some of which are not routinely designated in the literature as "syndromes," but they possess sufficient syndromic characteristics to be included.