Introduction: Pontocerebellar hypoplasia (PCH) is a reduction of the size of the cerebellum and pons secondary to an alteration in its development, and can be caused by neurodegenerative diseases of genetic origin, of which there are known 10 subtypes (PCH 1-10), cortical malformations, metabolic and genetic diseases.
Objective: To present the case of a child with microcephaly, PCH and West syndrome, in which the genetic study allowed to make the diagnosis of a deletion on chromosome X.
Case Report: This is a female infant of 7-month at diagnosis, without family or obstetric history of interest, head circumference at birth -1.