David Cameron has apologised after he said facing the shadow chancellor in Parliament was "like having someone with Tourette's sitting opposite you".
"I was speaking off the cuff and if I offended anyone, I am very sorry," he told the BBC's Andrew Marr.
The prime minister initially made his comments about Ed Balls's heckling in an interview with the Sunday Telegraph.
Nicky Clark, whose daughter has Tourette syndrome, said his comments showed "a lack of understanding".
Mrs Clark, who is from Shropshire, told BBC 5 live's Breakfast show that "comments like this compound the myths and the stereotypes surrounding people with Tourette's in Britain".
She added: "If we're supposed to look to him as some kind of lead, is this the best we can expect and disabled people expect?
"This comment comes in the middle of a piece about a fairer Britain. How fair is Britain going to be for disabled people if this is the lead we get from Downing Street?
"This shows an utter disregard for the condition and a lack of understanding from our prime minister."
Posted: Sun Jan 08, 2012 2:48 pm