Abstract
We present a case report of patient H., a four-year-old male who was brought to the neurogenetics clinic of a university hospital. He was diagnosed with Williams syndrome (WS), which was confirmed by microarray; the patient was also diagnosed with autism spectrum disorder (ASD) by the pediatric neurology department. It is known that due to WS's phenotypical pattern, a co-diagnosis of both ASD and WS is apparently unlikely and often ignored. This case report discusses how this matter is addressed in the literature to understand the overlap of these two diseases, treating this case as a study model.