A terminal deletion of the long arm of chromosome 4 [46,XX,del(4)(q33)] in an infant with phenotypic features of Williams syndrome.

A female infant with peripheral pulmonary artery stenosis, growth retardation, and developmental delay was noticed to have facial features consistent with a diagnosis of Williams syndrome. Chromosome analysis revealed a deletion of the terminal portion of the long arm of chromosome 4 (4q33----qter). This is the seventh reported case of this chromosome disorder. It is possible that this chromosome region is specific for the Williams syndrome phenotype but it is more likely that the syndrome is heterogeneous. Chromosome analysis should be performed in all suspected cases with particular attention to the long arm of chromosome 4.