Interstitial duplication of proximal 22q: phenotypic overlap with cat eye syndrome.

We describe a child with downslanting palpebral fissures, preauricular malfunctions, congenital heart defect (total anomalous pulmonary venous return), unilateral absence of a kidney, and developmental delay with an apparent interstitial duplication of proximal 22q. Fluorescent in situ hybridization (FISH) analysis showed duplication of the IGLC locus, and C-banding of the duplicated region was negative. The duplication appears to involve 22q11.2-q12. Although the child has neither colobomas nor microphthalmia, he shows phenotypic overlap with the cat eye syndrome, which is caused by a supernumerary bisatellited chromosome arising from inverted duplication of the short arm and proximal long arm of chromosome 22. Further molecular studies of this patient should help to define the regions responsible for the manifestations of cat eye syndrome.