A Canadian study compared the rate of cognitive disabilities in 156 relatives of 49 individuals with autism to that found in 55 relatives of 18 individuals with mental retardation. No differences were found; however, female and low IQ individuals were found to have higher family histories of cognitive disabilities. (Author/CR)

Platelet serotonin (5HT) levels of 5 autistic subjects (ages 16-37) who had siblings with either autism or pervasive developmental disorder were significantly higher than levels of 23 autistic subjects without affected siblings. Autistic subjects without affected siblings had 5HT levels significantly higher than 10 normal controls. Sex, age, and…

This final report reviews the second phase of a life-span study of boys with fragile X syndrome (FSX), the most common known inherited cause of mental retardation. Males with the syndrome are more severely affected than females and in males, delays are usually evident in all the developmental domains, although cognitive and communication skills…