The clinical characteristics of 20 children younger than 7½ years of age with the fragile X syndrome were reviewed at the Cincinnati Center for Developmental Disorders, Children’s Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati. The study was undertaken to establish guidelines that would aid the practicing physician in determining which children should have a chromosomal analysis. All children in the study were developmentally delayed: 95% had speech delays; and 50% or more had short attention span with hyperactivity, temper tantrums, mouthing of objects, autistic behaviors and poor gross motor coordination. The family history was positive for mental retardation in 65%, and 90% had a family history of at least one of the following: mental retardation, learning disabilities, or hyperactivity. The most common physical findings included long and/or wide and/or protruding ears in 15 (75%), prominent jaw or long face in 14 (70%), high arched palate in 10 (50%), flattened nasal bridge in 10 (50%), macrocephaly in 8 (40%), hypertelorism 8 (40%), and epicanthic folds 8 (40%), and Simian creases of palms in 7 (35%). Only 17% had relative increase in testicular volume. The authors believe that a chromosomal test for fragile X is likely to be of diagnostic benefit in young children with developmental delay (particularly in speech), a maternal family history for mental retardation or developmental disabilities, and long and/or wide and/or protruding ears. 
COMMENT. Martin and Bell first showed the association of mental retardation with the X chromosome and the marker X, now known as the fragile X, was first described in 1969 by Lubs. Sutherland discovered the method to enhance expression of the fragile site on the human chromosomes, dependent on folic acid deficient tissue culture medium (1977). In the adult, the classical triad of physical findings in the fragile X syndrome consists of a long face with prominent jaw, large prominent ears and macroorchidism. A number of different minor nonspecific dysmorphic characteristics have been noted in the occasional affected female but no large group of young girls with fragile X syndrome have been described.