A family faces an anxious wait after being told all four of them could get leukaemia. Rachel Simpson, 15, was diagnosed last year with a one-in-a-million genetic condition which doctors say will eventually give her cancer if untreated. The rest of the family, from Heysham, near Lancaster, are now waiting on tests which could reveal which of them also have a mutation of the GATA2 gene. The GATA2 gene is important in the production of blood cells, and the disorder means a sufferer's blood count might be low, making them more vulnerable to infection. Alternatively, the blood cells might be abnormal, leading to leukaemia. Rachel Simpson, 15, has a one-in-a-million genetic condition which doctors say will eventually give her cancer if untreated. The rest of her family (her mother, Donna, father Derek and brother Steven are pictured) are now waiting on tests which could reveal who else has the faulty gene . Miss Simpson's mother Donna, who works as an artisan cake maker, said the rest of the family will find out their fate in the next few weeks. And despite the family fears, her daughter had taken the news as best she could. She said: 'Getting a diagnosis like that, it's a bit mixed. As a parent your feel like your insides have been ripped out, you've got to be brave. 'But there's also relief that we know what's wrong so she can deal with it. 'She's been absolutely amazing, we've not had any tears, nothing, she's ever so matter of fact about it, she understands all the consequences, they explained it all, and she's been so mature.' She explained her daughter's diagnosis came after years of illness. 'She's been getting ill for the last two or three years - she kept getting pneumonia and cellulitis; any infection around she just seems to get.' Baffled, doctors ran blood tests - which revealed she had a mutation of the GATA2 gene. Mrs Simpson said: 'The rest of us have had our fair share of problems, but no more than anybody else. 'We're just waiting for the tests to come back to see if we have the mutation.' Miss Simpson suffers from a mutation of the GATA2 gene. This is important in the production of blood cells, and the disorder means a sufferer's blood counts might be low, making them more vulnerable to infection. Or, the blood cells might be abnormal, leading to leukaemia . Doctors say the mutation's frequency is less than one in a million - and one member of a family has a 50/50 per cent chance of passing it on . She added that despite the bad news about the mutation, the family were grateful for the testing. 'A few years ago we'd have never found out until Rachel got leukaemia,' she said. 'But now they but now they can predict it, which is amazing. She added: 'God willing, I want my son Steven to be OK. We've already been told he's not a bone marrow match, so Rachel will need to go on the bone marrow register.' Professor Inderjeet Dokal, of St Bartholomew's Hospital in London, is an expert in Rachel's condition. He said: 'This mutation's frequency is less than one in a million, it's a very rare genetic disorder. 'One member of a family has a 50/50 chance of passing it on, but it can also be the first time in the family that the genetic mutation occurs. 'If we assume one of the parents has it, then there's a significant possibility that her brothers and sisters have the defect, although they may not have symptoms.' He added: 'If they have the same defect, they can't be a bone marrow donor. 'The donor has to be both tissue type compatible and also negative for the mutation, so it makes it more difficult to find a suitable donor.'
Rachel Simpson, 15, diagnosed with one-in-a-million genetic condition .
Has mutation of the GATA2 gene, making her vulnerable to infection .
Can also make blood cells abnormal, leading to leukaemia .
The other members of her family will find out their fate in next few weeks .