Microtia: A clinical and genetic study at the National Institute of Pediatrics in Mexico city

Background. Microtia is a malformation of the ear with extreme variability of expression. It is generally seen as an isolated malformation. However, s ome authors consider it to be a minimal manifestation of the oculo-auriculo -vertebral spectrum (OAVS), where, in addition, then are facial, vertebral, and renal abnormalities, among others. Methods. A total of 145 pediatric patients with unilateral or bilateral mic rotia not considered as part of a syndrome were studied. All patients were subjected to an intentional clinical examination, a familial history; and r adiographic imaging studies for ruling out associated malformations. Patien ts were classified into two groups: group 1 (60%), with isolated microtia; and group 2 (40%), considered as OAVS, with microtia associated with hemifa cial skeletal microsomia, vertebral and/or renal malformations. Results. No significant differences were found between the groups when the following variables were compared: gender; presence of unilateral or bilate ral microtia; atretic external auditory canal; presence of preauricular tag s; hearing loss of any type, and affection of the seventh cranial nerve, as well as associated malformations of other organs or systems. There were si gnificant differences in relation to the presence of soft-tissue hemifacial microsomia, more frequently seen in patients with OAVS, because the majori ty of these patients had bone microsomia. Over 66% of the cases were sporad ic and the rest were familiar. In 28.3% of the cases, the history suggested an autosomal-dominant inheritance pattern, and in 5.5%, an autosomal-reces sive inheritance pattern, although in some familial cases, multifactorial i nheritance could not be ignored. Some members in several families had isola ted microtia, and others had mild characteristic manifestations of OAVS. Conclusions. Our results support the hypothesis that isolated microtia is a minimal expression of OAVS. Therefore, it is recommended that patients wit h microtia be subjected to intentional studies that search for malformation s and physical examinations of first-degree relatives for adequate genetic counseling and management. (C) 1999 IMSS. Published by Elsevier Science Inc .