Spinal muscular atrophy is the second most prevalent genetic cause of infant death in the UK, after cystic fibrosis.
Studies show that between 1:50 and 1:34 of the population are carriers of the disease, and that it affects in the region of 1:10,000 children born in the UK. In the USA, 1:40 are carriers and 1:6,000 children are affected by the disease.
SMA is a neuromuscular condition causing weakness of the muscles. The gene for SMA is passed from parents to their children, but SMA can only affect a child if both parents carry a defective gene. Genes come in pairs, one from each parent. If a person has one normal and one affected gene they do not show the symptoms of SMA but are carriers. If both genes are affected they will have SMA.
Researchers at the Peninsula Medical School in Exeter, UK, have carried out studies into one of the two survival motor neuron (SMN) genes that set suffers from SMA apart from the rest of the population. In 98% of SMA sufferers, the SMN protein is only produced from one of these genes. The resulting fall in SMN protein levels is what causes SMA to develop.
The remaining two per cent of SMA sufferers produce normal levels of SMN protein, but the protein is altered so that it is no longer capable of performing its normal functions within the body. One of the main reasons for this is that these disease-causing alterations in the SMN protein prevent it from localising to the correct places in the body's cells. By looking at why mutations occur and what they do to divert protein away from the cellular areas where it is required, the Peninsula Medical School team may be able to identify compounds that alter the protein so that it is directed correctly -- effectively producing a treatment for the disease.
The research could also have potential bearings on other treatments, such as gene therapy.
The research team is developing a number of other research projects in this area, as well as looking at non-invasive ways of carrying out tests in clinical trials -- such as identifying SMA from saliva rather than blood samples.
The team is headed up by Dr. Philip Young, researcher and lecturer in biomedical science at the Peninsula Medical School. He said: "Although our results have no initial translational impact on patients, they highlight why alterations in the SMN protein could prevent it from functioning properly. This is important because if we can help the altered protein function we could potentially identify a novel therapeutic approach."
Twins Bethany and Ceri Astill, 11, from Torpoint, Plymouth, UK, were diagnosed with type 2 SMA around the time of their second birthday.
Mum Sian said: "We noticed that they were slow in trying to walk, and were intent on using their own unique ways of getting around. They were given the "lazy label" for a while, but a little after their first birthday our GP referred them to Derriford where they had a number of tests. A genetic blood test a few months later confirmed that they had type 2 SMA."
The girls are determined to be as much the same as other youngsters of their age, and they have always attended mainstream schools with the support of one-to-one carers. They have just started at Torpoint Community College, and they have a passion for music and drama.
Said Sian: "Although they have the daily struggle of getting around and doing everyday things that you or I take for granted, they are remarkably positive and outgoing -- so much so that we are often put in contact with families with recently diagnosed children to offer support and to explain how the condition can affect daily life."
Despite both undergoing spinal surgery in late June, the girls remain upbeat and are not adverse to turning down challenges from the most well-known of challenge makers -- Anika Rice. Earlier this year they took part in a Challenge Anika programme that was broadcast in early June, to raise money for the children¡¯s hospice movement. The girls and Sian were flown to London on Mohammed Al-Faed's private helicopter, and even recorded a track for a charity album with Duncan James from Blue.
Said Sian: "There's really no stopping them, and we are so proud of the way they go about dealing with their condition."
This research is published in Human Molecular Genetics.
Materials provided by Peninsula College of Medicine and Dentistry. Note: Content may be edited for style and length.
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