A teenager could have died after being startled by the ringing of a telephone, an inquest was told yesterday.

Kasia Ber died in bed at her parents' home in Horden, County Durham, on December 28, last year.

A post-mortem examination revealed that the 17-year-old was suffering from a genetic heart disorder, known as Long QT syndrome, which had gone undetected.

Hartlepool Coroner Malcolm Donnelly said the cause of death was congenital fatal ventricular arrythmia, brought on by Long QT syndrome.

He read out a letter from Kasia's boyfriend, Scott Wheatley, in which he said they had been woken by a phone alarm at 7am on December 28.

The letter said: "Kasia said my name and she was shaking slightly. I held her to comfort her, and then I realised she had stopped breathing."

A statement issued by the Bers' solicitor, David Gripton, said: "Ventricular arrythmias are precipitated by stimuli that involve production of adrenaline - such as fear or sudden or loud noises - as in Kasia's case, where the stimulus to the fatal ventricular rhythm disturbance may have been the telephone alarm ring."

Kasia's aunt died from a sudden arrythmia and her mother takes beta blockers to treat Long QT syndrome.

Since Kasia's death, two cousins have been diagnosed as having the same condition. But her brother, Christopher, has been given the all clear.

Mr Gripton questioned Dr Michael Wallace, who had examined Kasia two weeks before her death while he was working as a locum at Jupiter House medical practice, in Sunderland Road, Horden.

She had complained of suffering from palpitations and shortness of breath.

Dr Wallace said he had attributed her complaints to stress or panic attacks, and an ECG had not revealed Kasia's heart condition.

He also said he was unaware at the time of a sudden death in the family, or that Kasia's mother suffered from Long QT.

Mr Donnelly recorded a narrative verdict that "Kasia died as a result of an undiagnosed genetic condition".

Speaking at their home in Brier Avenue, Horden, last night, Kasia's parents, John and Diane Ber, told of the devastation caused by losing their daughter.

Mr Ber said: "She was so vibrant, so full of fun - the joker in the pack. She was also very caring and studious."

The couple said they were disappointed with the inquest.

Mr Ber said: "We think the coroner should have used his powers to make recommendations about screening teenagers like Kasia when they show symptoms of heart problems."

Kasia's death provoked an angry reaction from two of the region's MPs who have campaigned for young people who display signs of heart defects to be screened as a matter of course.

Dari Taylor, MP for Stockton South, pushed through a Private Members Bill in the House of Commons two years ago calling for GPs to be given directives on how to deal with such cases.

She said last night that two years down the line after the Bill had gone through, young people were still dying needlessly.

Kevan Jones, MP for Durham North, backed Mrs Taylor's Bill and has continued to campaign with her for the screening of youngsters.

He said of Kasia's death: "This is just one of eight young people a week who die from sudden cardiac arrest.

"We must raise awareness of this condition, which has a devastating effect on families."