The Wechsler Intelligence Scales, Wide Range Achievement Test, and the
Shipley-Hartford Test were administered to 122 parents and 153 siblings of
62 autistic probands in Utah. Scores were distributed as expected within
the published normative ranges for each scale. Parents' scores correlated
with those of their nonautistic children, but neither parents' nor
siblings' scores correlated with the IQ level of the autistic probands.
These results do not confirm prior reports from England and the United
States of a high rate of cognitive and learning problems in the siblings of
autistic individuals, nor the aggregation of such problems in the siblings
of probands with high or low levels of cognitive function.