Medical condition of the week – Williams syndrome

The medical condition of the week this week is Williams syndrome, a genetic disorder which can cause an array of different symptoms. Williams syndrome is thought to affect about 1 in 7,500-20,000 people and is caused by a deletion mutation of chromosome 7 (in other words, some of the 7th chromosome is missing). It is thought that there are more than 25 genes deleted from chromosome 7, although this is not always the case in every sufferer of Williams syndrome. Unlike many genetic disorders, Williams syndrome is not inherited, and so effects both males and females equally. Instead, the deletion of genes occurs due to a random mutation during embryonic development. Also unlike many genetic disorders, Williams syndrome is autosomal dominant, meaning that an individual only has to have one chromosome missing the genes in order to display the characteristics of Williams syndrome (or the phenotype).

The main characteristics of Williams syndrome include mild to moderate learning disability, distinctive facial feature, cardiovascular related problems and what is often say to be unique personality characteristics.

Distinctive facial features are see with most children with Williams syndrome and are often referred to as “elfin” like. They include; a broad forehead; a short upturned nose; full cheeks and a wide mouth and full lips. It is also not uncommon for children with Williams syndrome and blue/green eyes to have a “starburst” or white lacy pattern on their iris. Due to these distinctive facial features children with Williams syndrome often have widely spaced teeth which may be crooked or missing. However, most of these dental abnormalities are easily corrected by orthodontic treatment.

The majority of people with Williams syndrome also have problems with their cardiovascular system, some of the most common being supravalvular aortic stenosis (SVAS) a narrowing of the aorta, (the main blood vessel to the heart) or narrowing of the pulmonary artery, (main blood vessel into the lungs). In many cases this narrowing is insignificant, and requires not treatment just monitoring. However, if the narrowing is severe it may require a surgery to correct it.

Some young children with Williams syndrome also have hypercalcemia, high calcium levels in the blood. However, most of the time this resolves itself during childhood, however occasionally treatment with medication or a change in diet may be required. Abnormalities of connective tissue is also seen in people with Williams syndrome, this can result in joint problems, and skin which is often soft and loose. However, physiotherapy and occupational therapy can often help with this.

As children many people with Williams syndrome are diagnosed with “failure to thrive”, and can often have problems feeding. These have been linked to severe gag reflex and low muscle tone among other things. However, these tend to resolve themselves as sufferers get older. Other problems which have been linked to Williams syndrome include; abnormalities in the Kidney structure or function; umbilical and groin hernias; and hypersensitive hearing, found in about 90% of children with Williams syndrome.

Many children with Williams syndrome have attention deficit disorder (ADD), developmental delays and learning disabilities, and many have difficulty with visual-spatial tasks (e.g. drawing) and fine motor skills. However, children with Williams syndrome are often loveable and have a very friendly personality, particularly they are noted for their expressive language skills and their politeness. Children with Williams syndrome also tend to have a high affinity for music and are very gifted in this area.

Sadly, like many other genetic conditions there is currently no “cure” for Williams syndrome. However, the associated conditions such as hypercalcaemia and SVAS can be treated; and work with physiotherapists, speech therapists and occupational therapists can also help sufferers of Williams syndrome to reach their full potential. Hopefully, with advances in the future into genetic testing, screening and gene therapy, even if conditions such as Williams syndrome cannot be cured, they can at least be more widely known.

Sources:
http://learn.genetics.utah.edu/content/disorders/chromosomal/williams/
http://www.williams-syndrome.org/

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Combating blindness with gene therapy

Surgeons in Oxford have used a new technique of gene therapy to help improve the vision of six patients who would have gone blind without the treatment.

The condition which the gene therapy was used to treat choroidermeia, a condition which causes the light-detecting cells at the back of the eye to determinate and dye gradually, leading to impaired site and finally complete blindness. The condition effects approximately 1,000 people in the UK and has causes the deterioration of vision in one in four people over the age of 75. The gene therapy itself begins by lifting the retina by injecting fluid into the back of the eye. DNA is then injected into the retina, inserting “working” copies of the faulty genes to prevent the rest of the light-detecting cells from dying.

Jonathan Wyatt, 63, was the first patient to undergo the gene therapy and found that, not only did the operation stabilise his vision, but it also significantly improves it, allowing him to now read three lines further down on an optician’s sight chart. Before the operation Mr Wyatt still had a little bit of vision, however since the operation his wife explained that “he is more independent, he can find things he couldn’t before, he can go to the shops on his own and he’s less of a nuisance!”.

There was also success for the other patients in the trial. Wayne Thompson, said that he noticed an immediate effect after the operation saying “my colour vision improves. Trees and flowers seemed much more vivid and I was able to see start for the first time since I was 17 when my vision began to deteriorate”. After being told that he would not see his daughter, aged 9, grow up, he is now hoping to see his grandchildren grow up.

Professor Robert MacLaren, the surgeon who led the research was “absolutely delighted” by the outcome, saying “we really couldn’t ask for a better result”. He believes that the success of the process demonstrates the principle that gene therapy could be used to cure other forms of genetic blindness such as age-related macular degeneration and glaucoma. As summed up by Clara Aglen of the Royal National Institute of Blind People “As this process advances there is hope that is could be transferred across and provide a cure for these common causes of blindness”.

Source:
BBC news – http://www.bbc.co.uk/news/health-25718064