Revisiting the Etiology of Hemifacial Microsomia / Retomando la etiología de la microsomía hemifacial

Background: Hemifacial microsomia (HM) is one of the most common congenital facial malformations of newborns worldwide. Despite its prevalence, little is known about its etiology. Features of HM vary among different reports in the literature, affecting ears, mouth, and mandible on one or both sides. Purpose and Methods: We performed a systematic literature review to determine if there is new evidence regarding the pathological origins of HM. During a seven-month period (September 2010-April 2011) an exhaustive electronic database search was constructed. An inclusion criterion, which set the specific parameters of the electronic database search for this review, was implemented using a number of built-in search tools. Results: A total of 1,250 published reports were displayed upon entry of the Boolean phrase “etiology AND hemifacial microsomia.” Of these papers, all of the publications selected for by the inclusion criterion had been published within the last ten years. Concomitantly, with regards to etiological origins, selection of a specific paper had to convey theories or experimental approaches of which had not been published as the main focus of a report more than three times in all with regards to previous documented literature with hemifacial microsomia as its basis. This final inclusion criterion left only eight studies eligible for this review. Reports included the suggestion of an etiologic role of growth hormone deficiency, fluoxetine ingestion, SALL4 expression, BAPX1 expression, and trisomy of chromosome 10. It appears that both genetic and environmental factors play a role in the etiology of HM. These factors include gene mutations, variation in serotonin receptor binding, growth hormone imbalances, and chromosomal abnormalities. Future studies in humans should determine the frequency of etiologic coding mutations in SALL4, BAPX1, and trisomy 10 in HM cases. Antecedentes: la microsomia hemifacial (MH) es una de las malformaciones faciales congenitas mas frecuentes en recien nacidos mundialmente. A pesar de su prevalencia, poco se sabe sobre su etiologia. Las caracteristicas de la MH varian en los diferentes reportes de la literatura; afecta oidos, boca y mandibula, uni o bilateralmente. Proposito y metodos: se llevo a cabo una revision sistematica de la literatura para determinar si hay nueva evidencia sobre el origen patologico de la MH. Durante siete meses (septiembre de 2010-abril de 2011) realizamos una busqueda exhaustiva en bases de datos electronicas. Un criterio de inclusion que determino los parametros especificos de la busqueda se implemento usando un numero de herramientas de busqueda. Resultados: la busqueda booleana (“etiology AND hemifacial microsomia”) arrojo un total de 1250 publicaciones. Se seleccionaron reportes publicados en los ultimos diez anos. Asimismo, con respecto a la etiologia, los articulos debian incluir teorias o experimentos que no se hubieran publicado como asunto principal mas de tres veces con la MH como base. Este criterio final de inclusion dejo solamente ocho estudios elegibles para la revision. Los reportes sugieren que una deficiencia en la hormona del crecimiento, ingestion de fluoxetina, expresion de SALL4, expresion de BAPX1 y trisomia del cromosoma 10 como factores etiologicos. Parece que factores geneticos y ambientales cumplen un papel en la etiologia de la MH. Estos factores incluyen mutaciones geneticas, variacion en la union del receptor de la serotonina, desbalances de la hormona del crecimiento y anomalias cromosomicas. Estudios futuros en humanos deberian determinar la frecuencia de mutaciones etiologicas en la codificacion de SALL4, BAPX1 y trisomia 10 en casos de MH.