Unilateral choanal atresia in one monozygotic twin: a case report.

Unilateral atresia is an extremely uncommon congenital disorder in monozygotic twins. We present the first case in the literature of premature, monozygotic twins with no other congenital genetic defects other than only one twin with unilateral choanal atresia on the right side, being the other sibling completely normal. Diagnostic examinations performed to both twins consisted of nasal endoscopy, which revealed only one twin with unilateral choanal atresia; axial computed tomography scan; genetic analysis; chromosome analysis; abdominal ultrasound and echocardiography. In our cases the genetic-chromosomal analysis failed to support a possible cause of unilateral choanal atresia in one monozygotic twin, suggesting a multifactorial etiology.