A mum has spoken out about the condition which will rob her daughters of their lives before they reach their teens.
Ashleigh Lennon, seven, and Alisha, four, are the only sisters in the country to both suffer from the rare form of Batten's Disease. The condition, which affects just one in every 300,000 births, is untreatable, and the girls are unlikely to reach their twelfth birthdays.
Despite being born healthy, the girls' health has deteriorated over time. Ashleigh is now blind and paralysed, and Alisha has balance problems.
Their mum, Jane Lennon, 36, from Lancaster has an older daughter Lucy, 15, who does not have the condition as she has a different father.
The disease is the result of a faulty gene carried by Ms Lennon and Alisha and Ashleigh's dad. Ms Lennon said:
'Lots of us are probably carriers of a faulty gene, but would probably never know it. It is only when you meet someone with the same faulty gene and have children together that it could become a problem.'
Ashleigh was diagnosed with Late Infantile Batten's Disease when she was five. The family was told there was a one-in-four chance that her sister Alisha, then two, would also have it.
'The consultant just had to be very blunt and tell us the facts. It was a terrible shock to be told that Ashleigh had a terminal disease,' says their mother, 'Alisha was sat there on my knee at the time when he told us there was a 25 per cent chance she could also have the disease. Six months later, she was tested and also diagnosed with it.'
Ashleigh now cannot move or talk and is fed by a tube, whilst her sister Alisha is still walking and running but has begun to have regular seizures.
Jane said: 'Alisha was always very clever and was like a little genius and is very active. She just looks like any other four-year-old and it is hard knowing she will suffer the same fate as her sister. It almost seems that much more cruel knowing Alisha will lose her mobility as she is so active and full of life now.'
More information about Batten's Disease can be found at http://www.bdfa-uk.org.uk/