Evidence for autosomal recessive inheritance in 46 families with multiple incidences of autism

Abstract

Forty-six families with multiple incidences of autism (41 with 2 and 5 with 3 autistic probands) were ascertained. Classical segregation analyses revealed a maximum likelihood estimate of the segregation ratio of P = 0.19 .+-. 0.07. This is not significantly less than 0.25, the expected value for autosomal recessive inheritance. However, it is significantly less than 0.50, the expected value for autosomal dominant inheritance. The polygenic threshold model was tested and rejected over a full range of values of heritabiity and ascertainment probability for these families. Results are most consistent with the hypothesis of autosomal recessive inheritance in this subset of 46 families with multiple incidences of autism.