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

RESUMO

Background. Microtia is a malformation of the ear with extreme variability of expression. It is generally seean as an isolated malformation. However, some authors consider it to be a minimal manifestation of the oculo-auriculo-vertebral spectrum (OAVS), wherem, 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 international clinical examination, a familial history, and radiographic imaging studies for ruling out associated malformations. Patients were classified into two groups: group 1 (60 percent), with isolated microtia; and group 2 (40 percent), 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; prescence of unilateral or bilateral microtia; atretic external auditory canal; presence of preauricelar tags; hearing loss of any type, and affection of the seventh cranial nerve, as well as associated malformations of other otgans 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 percent of the cases were sporadic and the rest were familiar. In 28.3 percent of the cases, the history suggested an autosomal-dominant inheritance pattern, and in 5.5 percent, an autosomal-recessive inheritance pattent, although in some familial cases, multifactorial inheritance could not be ignored . Some members in several familes has 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 firstdegree relatives for adquate genetic counseling and management