Autism spectrum disorder (ASD) is an early-onset neurodevelopmental disorder characterized by deficits in communicative and social skills and repetitive behaviors and/or restricted interests. The genetic mechanism underlying ASD is as complex and heterogeneous as its clinical heterogeneity. Beckwith-Wiedemann syndrome (BWS) is a well-known human imprinting disorder characterized by macroglossia, visceromegaly, hemihypertrophy, abdominal wall defects and a number of other various developmental abnormalities with an increased risk for embryonal tumors. In the literature, a greater frequency of neurobehavioral issues including ASD has been reported in children with BWS. Here, we present a 7-year-old boy diagnosed with ASD and BWS admitted to our clinic with complaints of emotional and behavioral changes after suddenly losing his father due to myocardial infarction. Upon initial assessment and psychiatric examination, the ASD diagnosis was confirmed and the exacerbation of the symptoms was assumed to be related with his bereavement. The family was given psychoeducation and the boy was started on escitalopram 0.5 mg/day, gradually increased to 2.5 mg/day. One month after this intervention, the family reported significant improvements in his symptoms. Although BWS has not been studied as extensively as other genetic conditions associated with neurodevelopmental disorders, it may be important for us to expand our knowledge about ASD accompanying human imprinting diseases including BWS.