Leber Congenital Amaurosis (LCA) is a rare genetic eye disease that appears at birth or in the first few months of life. The extent of vision loss varies from patient to patient, but is generally more rapid and severe than other forms of retinal disease. LCA accounts for 5% of all retinal dystrophies and 20% of blindness in school age children.
LCA is actually a term given to a group of diseases that are caused by mutations in at least 17 genes. The gene mutations lead to failure in function of the photoreceptor cells (rod and cone cells that detect light), ultimately causing cell degeneration. Given the severity of the condition, it is one of the most extensively researched inherited retinal disorders (IRDs), and a number of clinical trials are underway.
There are many different types of LCA, and the disease can present differently in different children. However, there are some basic symptoms that are often associated with LCA. These include nystagmus (involuntary jerky rhythmic eye movement), photophobia (sensitivity to light) and slow pupillary response to light. Eye-pressing and rubbing the eyes with a knuckle or finger can be common in babies and children who have very little vision. This can cause damage to the cornea (keratoconus) and lens and may result in a loss of fatty tissue around the eyes causing the eyes to look deep-set.
The extent and progression of degeneration depends on the type of LCA the child has. However, children with LCA usually have severe vision loss of 20/400 or worse, meaning that they can see at 20 feet what a person with “normal” vision can see at 400 feet.
LCA is a very rare condition usually inherited in an autosomal recessive manner, meaning that a faulty copy of the gene must be inherited from both parents. It can be caused by a mutation in any one of a number of genes that are important for retinal function. There are rare incidences where the inheritance pattern may be autosomal dominant. For more information on inheritance patterns, visit Unlock Genetics: www.RetinaUK.org.uk/unlock/discover-inheritance-patterns.
At present (Sep 2019), there are no treatments for LCA available on the NHS. However, a number of clinical trials are on-going and one gene therapy, known as Luxturna (voretigene neparvovec), has received European Medicines Agency approval. It is currently undergoing NICE appraisal and we are expecting NICE to publish formal guidance on NHS funding in December 2019.
Luxturna is a gene replacement therapy designed for the treatment of autosomal recessive LCA caused by mutations in the RPE65 gene. People must have two faulty copies of RPE65, confirmed by genetic testing, as well as reasonable numbers of remaining viable retinal cells, in order to benefit from this treatment. Most of those eligible will be children and young people.
Luxturna is administered via injection into the back of the eye under general anaesthetic. The treatment only needs to be given once but each eye is treated separately, a few days or weeks apart. There is a risk of side effects, including further sight loss, but if successful, the treatment can result in sustained improvement in functional vision, especially low light vision. Up to date information on the availability of Luxturna is available from our Helpline: 0300 111 4000 or Helpline@RetinaUK.org.uk.
Information on clinical trials for other forms of LCA can be found at www.clinicaltrials.gov; you can also read about possible treatment approaches for retinal disease at https://retinauk.org.uk/research/approaches-to-treatment/. Many treatment approaches are specific to a particular gene fault, so it is important that those affected by the disease are referred for genetic testing so that they can access new treatments and clinical trial opportunities.
Retina UK is occasionally approached by researchers and companies looking for our help in recruiting participants for studies or patient involvement initiatives, and we can pass on details of opportunities to people on our database who have expressed an interest in these activities and given consent to be contacted. Anyone who is not already in touch with Retina UK can call 01280 821334 or email info@RetinaUK.org.uk so that we can add them to our database. It is helpful for us to have as much detail about the diagnosis as possible, including genetic diagnosis if available, as some opportunities are condition specific.
The Retina UK Helpline provides information, support and signposting to people affected by inherited sight loss as well as healthcare and education professionals.
Contact 0300 111 4000 (9.30am – 9.30pm Mon to Fri) or Helpline@RetinaUK.org.uk.