Monozygotic twins concordant for autism and hyperlexia.

The authors describe male monozygotic twins, Jon and Jay, who are concordant for autism and hyperlexia. Autism and mental retardation were diagnosed at the age of 2 years 5 months. Jay was the more advanced twin in motor co-ordination, attention span and receptive abilities, but had frequent tantrums. When psychologically assessed at 7 years 2 months, Jon showed borderline/severe mental retardation on the measure of non-verbal intelligence and Jay was moderately retarded. Their receptive language age was greater than their expressive language age: Jon's speech was less mature but more communicative and Jay's was perseverative and ritualistic. Even though Jon was the more mentally retarded twin, Jay was the more autistic in some behavioral aspects. These twins highlight the relationship between autism and hyperlexia.