Spinal Muscular Atrophy: Q&A
The parents of a baby girl who died of a genetic disease are hosting a fundraiser for the hospice which helped them through their ordeal.
Laura and Paul Taylor, of Grimsby's St Nicholas Drive, lost their daughter Grace to Spinal Muscular Atrophy (SMA) when she was just six months old.
The couple turned to St Andrew's Children's Hospice for support, and the staff have continued to help them in the aftermath of Grace’s death.
On Sunday the couple will host a Christmas fair at St Christopher's Methodist Church, Convamore Road, Grimsby, to raise money for the hospice.
But what is SMA and what are the symptoms?
Spinal muscular atrophy is a genetic disease that causes muscle weakness and a progressive loss of movement.
Described by the SMA Trust as “a devastating, genetic disease”, it causes the motor neurons of the spinal cord and brain stem to deteriorate. These cells are critically important, as they are responsible for supplying messages to muscle cells. The messages tell the muscles when to contract (shorten) and relax.
Without the proper input from the motor neurons, muscle cells cannot function properly. The muscle cells will, therefore, become much smaller (atrophy) and will produce symptoms of muscle weakness.
SMA is a leading genetic killer of infants and toddlers, with 50 per cent of the most severely diagnosed cases resulting in death by the age of two.
Children with a less severe form of SMA face the prospect of progressive muscle wasting, loss of mobility and motor function. Their minds, however, are unaffected.
Is there a cure?
There is currently no cure for SMA, but research is under way and several clinical trials have been conducted.
What are the symptoms?
SMA affects a person’s physical abilities, such as walking and breathing, but does not impact upon their mental development.
SMA can affect the muscles throughout the body, but it is those closest to the centre of the body, such as the shoulders, hips and back, that are usually the most seriously affected.
There are different types of SMA, with varying symptoms. Of childhood SMA there are four:
- Type 0 (develops before birth): A very severe form of SMA, it causes reduced movement of the foetus which is usually first noticed between weeks 30 and 36 of the pregnancy. Babies with type 0 SMA are hardly able to move and have problems breathing and swallowing.
- Type I (known as Werdnig-Hoffmann disease): Babies will suffer severe muscle weakness, which can cause problems with moving, eating, breathing and swallowing. They are usually unable to raise their head or sit without support.
Symptoms may be apparent at birth or during the first few months of life - they usually occur before the baby is six months old. Most children who have type I SMA are unlikely to live past their second birthday.
- Type II: Usually develops when an infant is between six and 18 months old. Infants have less severe symptoms than those with types 0 and I, but will usually become weaker over time.
Infants with type II SMA will usually be able to sit, but it is unlikely they’ll be able to stand or walk unaided. They may also have breathing problems; floppy arms and legs; reduced or absent tendon reflexes and twitching of the muscles in the arms, legs or tongue.
As they grow, most children with type II SMA will develop scoliosis of their spine - an abnormal curvature of the spine to one side.
- Type III (known as Kugelberg-Welander disease): The mildest form of childhood SMA, but the symptoms and their severity can vary greatly.
A diagnosis is usually only made after the age of two, and the symptoms usually develop between early childhood and early adulthood.
Most children with type III SMA are able to stand unaided and walk, but they may have balance problems; difficulty running or climbing steps and a slight tremor of their fingers.
Over time, the muscles of children with type III SMA will become weaker, and those who are able to walk may be unable to do so when they get older.
There are two types of adult SMA:
- Type IV: Type IV SMA begins in adulthood. The symptoms are usually mild to moderate, start to develop after the age of 35, and progress very slowly.
In most cases, muscle weakness initially affects just one side of the body, before eventually progressing to both sides. Symptoms may include muscle weakness in the hands, feet and tongue; muscle tremor and twitching; and speech impairment.
- Kennedy’s syndrome (or spinal-bulbar muscular atrophy (SBMA): Only affects men. It usually develops between the ages of 20 and 40, although it can sometimes affect teenage boys and those aged over 40.
The initial symptoms may include a tremor of the hands; muscle cramps on exertion; muscle twitches and weakness of the muscles of the limbs. As the condition progresses further, other symptoms may include weakness of the facial and tongue muscles, which may cause difficulty swallowing (dysphagia) and slurred speech and recurring pneumonia.
Some sufferers may experience an enlargement of the male breasts (gynecomastia); a low sperm count or infertility or diabetes mellitus, an excess of glucose (sugar) in the blood.
What causes SMA?
SMA is caused by one or more faulty genes. It is usually inherited, which means the genes can be passed on from parents to children.
For a child to develop SMA, both parents must have the defective gene and pass it on to their child. These parents are known as carriers, and don't actually have SMA.
If both parents are SMA carriers and have a child, there is a 50 per cent chance the child will be a carrier of SMA and a 25 per cent chance that the child will develop SMA.
Approximately one in every 40 people is a carrier of the defective gene that causes SMA.
Find out more about the causes here.
How is SMA treated?
Until an effective treatment for SMA can be found, the management of the condition currently focuses on relieving the symptoms and providing supportive care:
- More moderately affected children and adults with breathing difficulties can be given a special mask or mouthpiece to support their breathing
- If a baby with SMA is unable to swallow and is at risk of choking they may need to be fed through a tube that is attached directly to their stomach. This is known as a gastrostomy tube
- Physiotherapy is often used to help improve a child’s posture and range of movement, as well as helping to slow the development of scoliosis
- A specially made back brace, or corset, can be used to help support the back and encourage the spine to grow correctly
- An occupational therapist will be able to offer advice and support to improve the independence of someone with SMA
How common is SMA?
In the UK, it is estimated there are between 5,500 and 6,000 people with SMA at any one time.
One in every 6,000 births is affected by SMA.