Is poor grammar a symptom of williams syndrome?

Not specifically.: Symptoms include developmental delays, learning disabilities, and other medical problems-cardiovascular in particular. They can have striking verbal capabilities, highly social personalities and affinity for music.

William's Syndrome: Children and adults with williams’s syndrome have very impressive social and verbal abilities. Their verbal abilities surpass their overall IQ scores. The language used by individuals with williams’s syndrome differs notably from other children with a similar IQ who do not have williams syndrome. They also tend to use speech that is rich in emotional descriptors.