Balanced rearrangements of the autosomes: results of a longitudinal study of a newborn survey population.

Thirty-six infants were identified by cytogenetic screening at birth as having balanced rearrangements of their autosomes, and 30 of them took part in a longitudinal study of their development, together with four of their affected sibs. With the exception of one child with a de novo reciprocal translocation who died, all children attended normal schools. Congenital malformations and short stature were present in only one child who had a de novo reciprocal translocation. The IQ scores of the 10 children with de novo translocations were significantly lower than those of the 20 children with familial translocations, but there were children in the de novo group of above average intelligence. Children with familial reciprocal translocations had significantly higher IQ scores than both the Robertsonian translocations and the controls, but the numbers in each category were small and a variety of different chromosomes were involved.