Microtia: a clinical and genetic study at the National Institute of Pediatrics in Mexico City

Abstract

Background: Microtia is a malformation of the ear with extreme variability of expression. It is generally seen as an isolated malformation. However, some authors consider it to be a minimal manifestation of the oculo-auriculo-vertebral spectrum (OAVS), where, in addition, there are facial, vertebral, and renal abnormalities, among others.

Methods: A total of 145 pediatric patients with unilateral or bilateral microtia not considered as part of a syndrome were studied. All patients were subjected to an intentional clinical examination, a familial history, and radiographic imaging studies for ruling out associated malformations. Patients were classified into two groups: group 1 (60%), with isolated microtia; and group 2 (40%), considered as OAVS, with microtia associated with hemifacial 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 bilateral microtia; atretic external auditory canal; presence of preauricular tags; hearing loss of any type, and affection of the seventh cranial nerve, as well as associated malformations of other organs or systems. There were significant differences in relation to the presence of soft-tissue hemifacial microsomia, more frequently seen in patients with OAVS, because the majority of these patients had bone microsomia. Over 66% of the cases were sporadic 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-recessive inheritance pattern, although in some familial cases, multifactorial inheritance could not be ignored. Some members in several families had isolated 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 with microtia be subjected to intentional studies that search for malformations and physical examinations of first-degree relatives for adequate genetic counseling and management.