London: Scientists have identified a protein that causes muscle damage in children with a form of motor neurone disease, a finding which they say could soon lead to new drugs to help reverse the damage.
The disease, called spinal muscular atrophy (SMA) or the "floppy baby syndrome", is the leading genetic cause of death in children. It affects one in 6,000 births, but 50 per cent of those with the most severe form die before the age of two.
In a study on mice, a team at the University of Edinburgh in the UK found that muscles of children with SMA are damaged by having low levels of a protein called SMN which is caused by a genetic mutation.
This mutation also disrupts the muscles` blood supply, leading to further damage, the researchers said.
In a second study, the researchers treated mice with SMA with a class of drugs known as HDAC inhibitors and found that the treatment increased the levels of the protein in muscle by targeting the genetic mutation.
"SMA is the most common genetic cause of infant death in the western world," said Dr Tom Gillingwater, a professor of neuroanatomy who led the Edinburgh study.
By showing the important role that muscles play in this disease, we can now focus our efforts on trying to block the disease in all affected tissues of the body," Dr Gillingwater was quoted as saying by the BBC News.
Research is now under way, looking at whether HDAC or other drugs can be tailored to further improve muscle control and increase blood supply.
Children with SMA experience progressive muscle wastage, loss of mobility and motor function. There are three grades of the condition, with type one being the most severe. Most cases are detected when a baby is very young and displays problems eating, swallowing and breathing. Often they can also fail to cry when they are born.
Type 1 babies have floppy limbs and "flickering" tongues, while type 2 is usually picked up when children are between six and 18 months old and affected children are able to sit, but cannot walk.
Type 3 is the mildest form of the disease. Children are usually diagnosed over the age of two. Many have problems walking and may require a wheelchair.
However, SMA does not affect children`s mental abilities. It was known that in the condition, there is damage to the nerves. But the Edinburgh research team found they also suffer from unhealthy muscles -- and that this damage can occur even if the nerve connections are healthy.
Lucy Blythe, of the SMA Trust, which funded the research, said: "These findings are significant. This is a tragic condition, because so many babies with type 1 die before the age of two."