Stickler syndrome is a connective tissue disorder affecting about 1/7,500 newborn babies. Connective tissue, as its name suggests, is involved in connecting different parts of our body together. Stickler syndrome is caused by changes in the connective tissue.
What are the features of Stickler syndrome?
People with Stickler syndrome may have a cleft palate and a small lower jaw. These are two features that are part of the Pierre Robin Sequence. Of those with Stickler Syndrome, 60% have Pierre Robin sequence. The cleft palate is surgically repaired around 12-24 months of age.
The eyes can be affected, resulting in near sightedness. There is also an increased risk of cataracts and retinal detachment.
Hearing loss of some degree affects around 80% of people with Stickler Syndrome. If hearing loss is conductive (sound is not conducted from the external ear to the inner ear), it is often possible to improve it by surgery. However, surgery is frequently unable to improve hearing if the hearing loss is sensorineural (the hearing problem is in the inner ear, auditory nerve or auditory centers of the brain). Hearing aids can help hearing in both types of hearing loss.
The joints may be enlarged and hyperextensible (more flexible than other family members).
About half of those with Stickler syndrome have a heart defect called mitral valve prolapse. The mitral valve is a valve in the heart that allows blood to flow between two chambers of the heart (left atrium to the left ventricle) while preventing the blood from flowing in the opposite direction (left ventricle to the left atrium). Mitral valve prolapse is when this valve is looser or floppier than it should be. A person with this may feel tired and the heart may sometimes beat irregularly or faster than normal. It is possible to have mitral valve prolapse and have no symptoms at all. The heart is able pump adequate blood supply to the body and the condition does not tend to degenerate over time. Listening to the heart can detect mitral valve prolapse. If mitral valve prolapse is present, a doctor can advise possible treatments based on any symptoms that may occur. Before any dental work or surgery, it is important to consult with a doctor, as antibiotics may be required to prevent rare but serious infection in the heart.
This syndrome is a variable condition. The number of features displayed and the degree of effect varies between individuals.
What causes Stickler syndrome?
Stickler syndrome is caused by a change in one of the genes for connective tissue. There are three genes which have been identified that can cause this syndrome. A change in any one of the three genes can cause Stickler syndrome. The particular gene involved appears to have a bearing on the degree to which some features such as eyesight and hearing problems are present. There are some families with Stickler syndrome that are not linked to any of the three known genes, so there may be at least one other, unknown gene involved.
Can it happen again?
Stickler syndrome is an autosomal dominant condition, so males and females are equally likely to be affected. This means that once you have Stickler syndrome you have a 50% or 1 in 2 chance of passing it on to your children.
If your child is the first person in the family to have Stickler syndrome, then it is likely that the change was in a particular egg or sperm. There is a very low chance that you could have another child with Stickler syndrome.
Is there a test for Stickler syndrome?
Stickler syndrome is still diagnosed clinically and not by a genetic test. A genetic test may be used to try to confirm the syndrome. If a change is found then that can be used to test other members of the family who may be more mildly affected, if they wish to be tested.
Why not do genetic testing first?
The problem is that there may be other genes involved that are not yet known, so a negative result does not mean you do not have Stickler syndrome. In addition to this, the clinical significance of all the changes that could occur in the Stickler syndrome genes are not known, so finding a change does not mean you have the condition. If you have enough features to be diagnosed clinically with Stickler syndrome, and a change is found in one of the Stickler syndrome genes, then it is likely that the change is the cause of the Stickler syndrome features.
- Gorlin R.J., Cohen M.M., Hennekam R.C.: Syndromes of the Head and Neck. Oxford University Press, 1990.
- Jones K.L., Smith’s Recognizable Patterns of Human Malformation. 5th Edition. W.B. Soliders Company A Division of Harcourt Brace and Company, 1997.
- Online Mendelian Inheritance in Man, OMIM (TM). McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University (Baltimore, MD) and National Center for Biotechnology Information, National Library of Medicine (Bethesda, MD), 2000.