We report on a 41-year-old male with dysmorphic features, marked obesity, profound mental retardation, and aggressive behavior who was recently diagnosed with tetrasomy of the short arm of chromosome 18, [47, XY, i(18)(p10)]. His initial diagnosis, based upon chromosomal analysis at 6 years of age in 1969, was "trisomy F syndrome." Approximately 60 cases of… (More)