Partial Tetrasomy of Chromosome 22: Genetic and Surgical Implications for Otolaryngologists

Abstract

Partial tetrasomy of chromosome 22 is a rare mul tiple congen ital anomaly sy ndrome that is mare commonly known as cat-eye sy ndrome (CES). It is caused by the dupli cation ofa 2-million base regio n ofchromosome 22 (22 p ter-, q }}•2). The phenotype is extretnely variable, and its clinica l characteristics include a combination of craniofacial, cardiac , rena l, gas trointestinal, and genitourinary def ects. We describe a rare occurrence ofCES in a Brazil ianfa mily. Three siblings were affe cted-i-monozygotic twin boys and their y ounger brothet: All 3 were born to healthy nonconsanguineous parents. On examination, all 3 werefo und to have strab ismus, primary telecanthus , bilateral coloboma iridis , and low-set ears with posterior rotation ofthe p innae. Partial tetrasomy ofchromosome 22 was confirmed by fiuo rescent in si tu hy bridizat ion. To our knowledge, this is thefirst report ofsuch an occurrence in one family. We discuss the genotype and phenotype of CES, with particular reference to inheritance patterns and craniofac ial def ects.