ABSTRACT
Smith-Magenis syndrome (SMS) is characterized by distinctive facial features, developmental delay, cognitive impairment, and behavioral abnormalities and associated with interstitial deletion of chromosome 17p11.2. We report 2 cases of SMS with tetralogy of Fallot. The first patient was reported having a normal conventional karyotype 7 years ago. However, as she grew up, she showed more compatible findings with SMS in behavior and phenotype. On the second cytogenetic study, interstitial deletion of 17p11.2 was detected by conventional banding technique which had 550 band resolution and it was confirmed by metaphase fluorescence in situ hybridization (FISH) using D17S258 SMS probe (Oncor, Gaithersburg, MD, USA). The second patient showed subtle phenotypic feature except microcephaly and cardiac anomalies was confirmed as SMS by cytogenetic analysis and FISH. We suggest that FISH should be performed not to overlook the submicroscopic deletion when SMS is clinically suspected, even though cytogenetist can not detect any anomalies on the conventional cytogenetics. A confirmatory diagnosis using FISH would be helpful in terms of guiding medical management and leading to proper genetic counseling.