Developmental disorders symptoms, which impair basic skills in girls, were diagnosed at the age of 4 among girls compared to 3.8 years in boys.

For the study, the researchers analysed data from an online registry that includes almost 50,000 individuals and family members affected by ASD. In the data review, researchers found that girls were diagnosed with pervasive developmental disorder, an ASD impacting the development of many basic skills, at a mean age of four years compared to 3.8 years for boys.
In addition, they found girls struggled more with social cognition, the ability to interpret social cues. Meanwhile, boys had more severe mannerisms such as repetitive behaviors like hand flapping, as well as highly restricted interests.
Older boys, ages 10-15, also had more difficulties with the ability to recognize social cues and use language in social situations.
Source-Medindia