The authors found an association between both microtia forms with external auditory canal atresia in RE; only 20% of patients had unilateral auricular tags or pits in both groups. The authors also found a high incidence (18.75%) of familial microtia, which suggests a distinct pathological genetic component than the more prevalent isolated cases. The authors found a high association of microtia cases from the Ecuadorian highlands above 2500 meters about sea level (over 90%). The presence of "social" intake of alcohol during pregnancy showed over twice the chance of having a child born with microtia.