A 3 year old boy is brought with normal developmental milestones but has delayed speech difficulty in communication and concentration. He is not making friends. What is the MOST probable diagnosis in this child?

This child is most probably suffering from autism. Autism is a neurologic disorder characterized by qualitative impairment in social interaction and communication and presence of restricted repetitive and stereotyped patterns of behavior, interests, and activities. Pervasive developmental disorder: Children with this disorder have impaired social interaction and shows repetitive behaviors. They do not have significant delays in cognitive, language or self-help skills. Childhood disintegrative disorder: Children have normal development for 2 years following which there will be regression in at least one of the following areas: social interaction, communication, and behavior. Rett's syndrome is a genetic syndrome caused by a mutation on the X chromosome that is characterized by regression in skills in the first year of life. Ref: Goldson E., Reynolds A. (2012). Chapter 3. Child Development & Behavior. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.