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Ectodermal dysplasias are a group of genodermatoses characterized by dystrophy of ectodermal derived structures. The most frequent presentation of the ectodermal dysplasias is the hypohidrotic type, which has an incidence of 7/100,000 newborns and has been described in all ethnic groups. The hypohidrotic ectodermal dysplasia (HED) has different etiologies, and it is more frequently associated with an X-linked pattern of inheritance caused by pathogenic variants of the EDA gene in Xq13.1. EDA encodes the protein ectodisplasin A, a signal molecule which participates in epithelium and mesenchymal development of the skin.A 6 year-old male patient with the main clinical characteristics of the X-linked HED including hypotrichosis, hypodontia and hypohidrosis. The direct sequencing analysis of EDA in our patient detected a de novo pathogenic variant, c.466CT, p.Arg156Cys, rs132630313. This variant has been previously described in different ethnic groups, including Mexican families, and is considered a mutational hotspot. The clinical characteristics, etiology and management of the X-linked HED, including the possibility of prenatal therapy in order to avoid the clinical manifestations are discussed.The molecular analysis in patients with X-linked HED is of relevance, as it enables to confirm the clinical diagnosis and also, it allows a genetic assessment with molecular bases.Las displasias ectodérmicas son un grupo de genodermatosis que se caracterizan por distrofia de las estructuras derivadas del ectodermo. De ellas, la variedad más común es la hipohidrótica, con una incidencia de 7/100,000 nacidos vivos observada en todos los grupos étnicos. La displasia ectodérmica hipohidrótica tiene distintas etiologías. La presentación más frecuente es la asociada a un patrón de herencia ligado al cromosoma X, causada por variantes patogénicas del gen EDA en Xq13.1. EDA codifica a la ectodisplasina A, una molécula de señalización que participa en la comunicación epitelio-mesénquima durante el desarrollo de la piel y los anexos.Varón de 6 años con las características clínicas cardinales de la displasia ectodérmica hipohidrótica ligada al cromosoma X (DEHLX), que incluyen hipotricosis, oligodoncia e hipohidrosis. El análisis del gen EDA por secuenciación directa mostró la presencia de la variante patogénica c.466CT, p.Arg156Cys, rs132630313 con presentación de novo en el paciente. Esta variante ya ha sido reportada en diferentes poblaciones, incluyendo familias mexicanas, y constituye un punto caliente para mutación en EDA. Se analizaron los hallazgos clínicos, la etiología y el manejo de la DEHLX, en la que de manera reciente se ha planteado la posibilidad de otorgar tratamiento prenatal para prevenir sus manifestaciones clínicas.Se pone de relevancia que el análisis molecular en pacientes con DEHLX corrobora el diagnóstico clínico y permite brindar asesoramiento genético con bases moleculares.

Background Ectodermal dysplasias are a group of genodermatoses characterized by dystrophy of ectodermal derived structures. The most frequent presentation of the ectodermal dysplasias is the hypohidrotic type, which has an incidence of 7/100,000 newborns and has been described in all ethnic groups. The hypohidrotic ectodermal dysplasia (HED) has different etiologies, and it is more frequently associated with an X-linked pattern of inheritance caused by pathogenic variants of the EDA gene in Xq13.1. EDA encodes the protein ectodisplasin A, a signal molecule which participates in epithelium and mesenchymal development of the skin. Case report A 6 year-old male patient with the main clinical characteristics of the X-linked HED including hypotrichosis, hypodontia and hypohidrosis. The direct sequencing analysis of EDA in our patient detected a de novo pathogenic variant, c.466C>T, p.Arg156Cys, rs132630313. This variant has been previously described in different ethnic groups, including Mexican families, and is considered a mutational hotspot. The clinical characteristics, etiology and management of the X-linked HED, including the possibility of prenatal therapy in order to avoid the clinical manifestations are discussed. Conclusions The molecular analysis in patients with X-linked HED is of relevance, as it enables to confirm the clinical diagnosis and also, it allows a genetic assessment with molecular bases.