Here, using behavioral tests to assess neonatal thermosensory reactivity, we discovered the existence of early developmental deficits in thermal sensitivity in neonate mice lacking the autism-associated gene Magel2. MAGEL2 is an imprinted gene highly expressed in the hypothalamus that is paternally expressed and which paternal deletion and point mutation cause Prader-Willi [24] and Schaaf-Yang [25] respectively; two syndromes with high prevalence of ASD (27% and 78% respectively). This evidence concerns the gene MAGEL2 and autism.