Father gives up job to research cure for rare disease that is turning his sons' bones, eyeballs and sweat BLACK Daniel and Julien Sireau, 10 and 12, have Black Bone Disease Currently they are healthy but they will start to develop debilitating symptoms in early adulthood unless an effective treatment is found The disease causes severe, early-onset osteoarthritis as well as bone, urine, earwax and eyeball discolouration - can also cause heart disease The symptoms are caused by the rapid build up of toxic acid in the body Nick Sireau, the boys' father, has given up his job as CEO of a charity to help organise a clinical trial for a drug he believes will treat the disease If the trial is successful, the drug could be licenced and available on the NHS within five years Two brothers with a rare degenerative disease that causes their urine and bones to turn black have been given hope after their father gave up his job to look for a cure. Daniel and Julien Sireau, aged 10 and 12, have black bone disease - also known as Alkaptonuria (AKU) - which will cause them to develop severe early-onset osteoarthritis unless a cure can be found. The genetic disease causes the bones, cartilage, urine and earwax to turn black. It also results in brittle bones and heart disease. Julien (left) and Daniel (right) Sireau both have a genetic condition called Back Done Disease which causes their bones and urine to turn black. It also causes early-onset osteoarthritis and, possibly, heart disease Currently there is no treatment for the disease and Daniel and Julien could start to develop symptoms at any age from their mid-teens to their 40s. However, their father, Nick Sireau, 40, has given up his job as CEO of a charity called SolarAid - which aims to offer solar solutions to poverty - to help organise a clinical trial for a drug which he believes will offer a life-saving treatment for his children and all other AKU sufferers. Mr Sireau, from Cambridge, told MailOnline: "My hope is that my children never have to feel the pain of the symptoms - that they just won't have to worry about it." Just after Julien was born, Mr Sireau and his wife, Sonya, noticed that his nappies were turning black. They called an emergency doctor who thought the problem was caused by his mother eating red cabbage and then breastfeeding him. However, his parents were not convinced so took him to a GP who sent a range of tests to Great Ormond Street Children's Hospital. The boys' father, Nick (pictured with Daniel), gave up his job in 2010 to help find a cure for the condition. He believes a treatment has now been identified and is helping to organise a clinical trial Currently Julien (right) and Daniel (left) are healthy but they will start to develop symptoms in early adulthood unless a treatment is found When the tests were analysed, they revealed that Julien has Black Bone Disease which is a genetic disorder caused by a recessive gene. Mr Sireau said: "It took a lot of time to sink in. Doctors told us there was nothing we could do - that was very disempowering. It took us a while to start realising that we could do something. Black Bone Disease causes bone and cartilage to become discoloured. Image shows the elbow joint of an anonymous sufferer When the couple had their second child, Daniel, they knew there was a 25 per cent chance that he would also have the condition. Mr Sireau explained that after he was born, they kept checking his nappies for fear they too would go black. He said: "We were checking Daniel's nappies again and again. It was so sad when it happened but we try to be positive. We are given a chance to find a cure because the disease doesn't affect them as children. The boys are currently healthy but without treatment will eventually start to develop symptoms such as joint problems and back pain - the early symptoms of osteoarthritis. The osteoarthritis is caused by a toxic acid called homogentisic acid (HGA) attacking their bones and cartilage, turning them black and brittle. In people with Black Bone Disease, the acid accumulates at 2,000 times the normal rate. This also causes discolouration of the ears and black spots in the eyes. There is also a growing link between AKU and heart disease. This is because toxic acid called homogentisic acid HGA causes the blood vessels and valves in the heart to harden, turning them black, brittle and less effective at managing the flow of blood around the body. Although this is still believed to be an uncommon symptom of AKU, it is a potentially fatal consequence of the disease. Julien was diagnosed as a baby when his parents noticed his nappies were black - until then they did not realise they carried the gene mutation. There was a 25 per cent chance Daniel would also be affected AKU can also cause several other symptoms, such as kidney, prostate and bladder stones, black or dark sweat or a blue speckled discolouration of the skin. However, there is hope that all sufferers of Black Bone Disease will soon be able to live a normal life without developing any symptoms. In 2010 Mr Sireau gave up his job to join the AKU Society and help their search for a cure. He believes that a drug called Nitisinone could prevent HGA building up in patients and, therefore, prevent symptoms developing. Mr Sireau (pictured with Julien) believes the drug Nitisinone could prevent acid building up in patients and, therefore, prevent symptoms developing. The drug is already used to treat another rare disease The drug is already used to treat another rare disease and some Black Bone Disease patients have been able to access it in England. However, it is not currently licenced for use in people with Black Bone Disease meaning they fear it could become unavailable at any time - many patients can also currently not access it at all. Therefore, the AKU Society is organising a clinical trial involving 140 patients from across Europe in the hope of getting the drug licenced. The trial will take four years and will operate out of centres in Liverpool, Paris and Slovakia. Mr Sireau (pictured with Daniel) said: 'Personally, this means hope for my kids and for all of the patients. We hear the most horrible stories of people having to stop work and becoming depressed because of the symptoms. For me, it is important my kids don't suffer this pain' The medical side of the trial, which is expected to start at the end of the year, is being funded by the European Commission but the organisers need to raise $98,000 to pay for patient transport, carers for the more disabled patients and to provide support for patients. To date they have raised just over $40,000 and they only have 14 days left to raise the rest of the money. If the trial is successful, the treatment could be made available on the NHS within the next five years. If the drug trial is successful, the treatment could become available on the NHS within five years. Image shows Sonya Sireau Mr Sireau said: "Personally, this means hope for my kids and for all of the patients. For me, it is important my kids don't suffer this pain. To donate, visit www.indiegogo.com/projects/cure-black-bone-disease Black Bone Disease, also known as Alkaptonuria (AKU), is a rare genetic disease which causes early-onset osteoarthritis. It is causes by the lack of an enzyme called homogentisic dioxygenase which means that patients cannot fully breakdown a toxic acid called homogentisic acid. As a result, the acid builds up in the body at 2,000 times the normal rate. The first symptom is usually black urine. Other symptoms do not usually develop until the patient is in their 20s. At this stage, the patients tend to develop joint problems and back pain which is the start of osteoarthritis. This eventually causes the bones to become brittle and can be very disabling. The condition can also cause the eyeballs, sweat and earwax to turn black. It is thought there is also a link between AKU and potentially fatal heart disease. This is because HGA causes the blood vessels and valves in the heart to harden, turning them black, brittle and less effective at managing the flow of blood around the body. AKU is caused by a genetic mutation - it is a recessive disorder meaning the AKU gene must be carried by both of the patient's parents. If both parents are carriers, there is a 25 per cent chance of their child developing the condition. The condition is thought to occur in about one in every 250,000 to 500,000 people. Source: AKU Society