Family size limitation: a method for demonstrating recessive inheritance.

Limitation of family size after the birth of a child with a serious disorder poses a problem in demonstrating autosomal recessive inheritance. In this paper methods are presented for distinguishing autosomal recessive inheritance given a 100% deterrent effect, and revealing a partial deterrent effect by analysis of sibship size and comparison with general population data. These methods are illustrated using information from phenylketonuria families.