The deletion 22q13.3 syndrome (Phelan-McDermid syndrome) is a chromosome microdeletion syndrome characterized by neonatal hypotonia, global developmental delay, normal to accelerated growth, absent to severely delayed speech, and minor dysmorphic features. Common physical traits include long eye lashes, large or unusual ears, relatively large hands, dysplastic toenails, full brow, dolicocephaly, full cheeks, bulbous nose, and pointed chin. Behavior is autisticlike with decreased perception of pain and habitual chewing or mouthing. The loss of 22q13.3 can result from simple deletion, translocation, ring chromosome formation and less common structural changes affecting the long arm of chromosome 22, specifically the region containing the SHANK3 gene. The present case was referred at the age of 8 months because of delayed psychomotor development, hypotonia and autistic features. Clinical examination showed a small forehead, long eyelashes, epicanthal folds and lowset ears, large and broad hands and feet with short terminal phalanges. He had no eye contact and could not sit without support.