Rett's syndrome is characterized by all of the following EXCEPT

(D) Decrease head circumference at birth # Two syndromes with autistic features namely Asperger's syndrome & Rett's syndrome.> Asperger's syndrome is characterized by autism without any significant delay in language or cognitive development (including intelligence). This syndrome occurs predominantly in boys (male: female ratio = 8:1). It probably represents mild cases of autism.> Rett's syndrome is a disorder which is only reported in girls so far. After an apparently normal early development and normal head circumference at birth, there is a deceleration of head growth between the age of 5 months and 30 months. There is also a loss of purposive hand movements and acquired fine motor manipulative skills between the same ages, with subsequent development of stereotyped hand movements (e.g. hand wringing). Later, other movement disorders also develop and severe mental handicap is invariable.