An eight-year-old boy pleaded with his mother to kill him to rid him of the pain of a rare brain condition.

Greg Storey is tormented by Tourette syndrome, which causes sufferers to swear uncontrollably and give involuntary jerks and screams.

The youngster, from Pickering, North Yorkshire, will be the subject of a moving documentary, The Boy Can't Help It, to be screened on Wednesday.

His mother, Kim, a teacher, has been able to cope with most of the problems the condition has brought to their lives.

But she wept when Greg asked her: "Mam, please kill me to take away the pain."

Kim, 35, said: "He said he felt as if he should not be alive and wanted someone to kill him because the pain was too much.

"The second time, I was bathing him and he asked me to cut his throat."

She and husband Paul, 39, a police officer, are also living with the fear that their daughter, Elena, four, may develop the syndrome.

Paul said: "Elena and Greg fight like cat and dog, but she sticks up for him and if someone has a go at Greg she will tell them off."

The symptoms of Tourette, already distressing for the family, are likely to get worse as Greg enters adolescence.

But Kim said: "We will fight through it together every step of the way."