Unknown syndrome: Hirschsprung's disease, microcephaly, and iris coloboma: a new syndrome of defective neuronal migration.

We describe three children with Hirschsprung's disease and microcephaly, two of whom also have an iris coloboma. Two of the children, one with a coloboma and one without, are from the same consanguineous pedigree. The third case is unrelated and was identified by the matching program of the London Dysmorphology Database. This is the first report of this combination of features which are considered to be secondary to defective neuronal migration. An autosomal recessive mode of inheritance is proposed.