Two cases of deletion 2q37 associated with segregation of an unbalanced translocation 2;21: choanal atresia leading to misdiagnosis of CHARGE syndrome

Context: The phenotypic variability of patients with syndromes presenting with dysmorphism makes clinical diagnosis difficult, leading to an exhaustive genetic study to determine the underlying mechanism so that a proper diagnosis could be established. Objective: To genetically characterize siblings, the older sister diagnosed with Albright hereditary osteodystrophy and the younger one with CHARGE syndrome. Design: Clinical case report. Methods: Clinical, biochemical, and radiological studies were performed on the family. In addition, molecular genetic studies including sequencing of GNAS, typing of microsatellites on 2q and 21q, and multiplex ligation-dependent probe amplification of subtelomeric regions were performed, as well as confirmatory fluorescent in situ hybridization analysis. Results: The genetic analysis revealed that both sisters presented a 2q37 deletion due to the maternal unbalanced segregation of a 2;21 translocation. Conclusions: This is the first report of a 2q37 deletion where differential diagnosis of CHARGE syndrome is needed due to the appearance of choanal atresia.