Risk factors for Microtia and preventive approaches

Microtia is a congenital anomaly that directly affects the external ear. Although the etiology of this pathology is not fully elucidated, there are several factors that are associated with its occurrence, such as genetics, perinatal and maternal conditions. During organogenesis of the outer ear it is important to mention that as anomalies occur before the sixth week of pregnancy, the chances of severe defects or total absence of the outer ear increase. At the genetic level, the etiology of microtia has been related to multiple causes, as well as the identification of genes involved in allelic expression pathways and transcription factors. Furthermore, this anomaly does not always occur alone, but associated with other pathologies such as cleft palate (12.8%), cleft lip and palate (11.5%), anophthalmia/microphthalmia (11.5%), facial asymmetry (10.6%),  as well as oculoauriculovertebral spectrum syndromes, Goldenhar syndrome, craniofacial microsomia, Treacher Collins syndrome, Nager, DiGeorge or 22q deletion, Townes-Brock syndrome and branchi oto-renal syndrome. Treatments are based on the aesthetic management of the patient, but also related to the improvement of the patient's hearing ability. Epidemiologically, the prevalence ranges from 0.8 to 17.5 per 10,000 live births. One of the main risk factors for variation in case identification is altitude, genetics and maternal-perinatal factors. This literature review provides a thorough analysis of information for the better understanding, analysis and clinical management of this congenital anomaly.