Kousseff syndrome: a causally heterogeneous disorder.

The existence of Kousseff syndrome as a distinct entity has been thrown into doubt by a recent study conducted on the family originally reported by Kousseff. In all cases where chromosome 22q11.2 FISH testing has been undertaken, including the original sibship, a chromosome 22q11.2-microdeletion has been identified. We report two cases of sacral myelomeningocele associated with a conotruncal cardiac anomaly or "Kousseff syndrome." The first case, a 4-year-old girl, had a sacral myelomeningocele, tetralogy of Fallot, microcephaly, hydrocephalus, hypoplasia of the corpus callosum and mild-moderate developmental delay. Chromosome 22q11.2 FISH was normal and the facial phenotype was not that of velocardiofacial syndrome. Sequencing of the entire coding region of CITED2 did not reveal a mutation. The second case, a male infant, was found to have a 22q11.2-microdeletion. These cases confirm Kousseff syndrome to be a causally heterogeneous disorder.