Theoretically, microduplication of chromosomal region 22q11.2, which is rich in segmental duplications, should be as frequent as microdeletions of the same region. Preliminary analysis on the rarity of reports for 22q11.2 microduplication in the literature has suggested that, for the discovery of 22q11.2 microduplication, there has been a lack of sensitivity for routine diagnostic techniques such as karyotyping, PCR and FISH. On the other hand, the diverse anomalies and extremely variable phenotypes of carriers also implied great difficulties one has to face upon clinical consultation. Genetics as well as clinical problems in connection with 22q11.2 microduplication has vividly illustrated the great challenge for the interpretation of genotype-phenotype correlation, and thereby posed yet another gray zone for clinical genetics research.