What is Stickler Syndrome?
Stickler syndrome is a group of genetically inherited conditions that affects the collagen (connective tissue) in a person’s body. It is the most plentiful protein in the body – about one third of all our protein is made up of collagen. Collagen forms a major part of connective tissue, which can be described as the supportive tissue of the organs of the body. Some connective tissue acts like a glue or binding, in other areas it acts like scaffolding, and can also allow for the elastic stretching and tightening, especially in the muscles. Collagen is also an important part of the cartilage which covers the bone ends of the joints. In the eye it is found in the sclera, (the white of the eye) cornea and vitreous humour.
Why Stickler Syndrome?
Stickler syndrome is named after Dr Gunnar B Stickler who defined the condition in 1956. He named it Hereditary Progressive Arthro-ophthalmopathy, but colleagues called it Stickler Syndrome. In 1960 Dr Stickler examined a twelve year-old boy at the Mayo Foundation in Minnesota, USA. The boy had bony enlargements of several joints and was extremely short sighted. His mother was totally blind. Dr Stickler discovered that there were other members of the family with similar symptoms, the first family member having been seen by Dr Charles Mayo in 1887. This prompted Dr Stickler to study the family.
Who is affected?
Stickler Syndrome affects around 1 in 7,500 to 9,000 new born babies. If a parent has Stickler syndrome, there is a 50% chance of any children developing the condition. There are also recorded cases where the condition has occurred for the first time in a child. This is known as a spontaneous mutation.
What Types of Stickler Syndrome are there?
Mutations in the dominant genes COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, COL9A3 cause Stickler syndrome. COL9A1, COl9A2I and COL9A3 cause recessive Stickler syndrome, where the risk of parents having another affected child is less than 25% rather than 50%. Researchers believe that mutations in other genes also cause the condition and work is being carried out to identify these. The three most common are:
Type 1 – COL2A1 is responsible for Stickler syndrome in about 75% of people diagnosed with the condition. Most will have ‘full’ Stickler syndrome affecting the sight, joints, hearing and any mid-line clefting. Findings show those with this anomaly have an increased incidence of cleft abnormalities.
Type II – COL112A again causes ‘full’ stickler syndrome, and patients with this anomaly have more incidence of deafness. There is also a recessive variety of type II which has been identified in 3 people with very, severe deafness.
Type III -COL112A causes a non-ocular Stickler-like syndrome, which affects only the joints and hearing with no eye problems.
How Does s it affect a sufferer?
The symptoms and severity of Stickler syndrome vary from patient to patient, even within a family, and can be difficult to diagnose. There is a range of treatments and support available, and with this on-going help it is possible to learn to live within the limitations of the condition.
What are the symptoms?
- Short-sight (myopia)
- Abnormal appearance of the vitreous gel.
- High risk of retinal detachments (tearing of the lining of the eye), which may affect both eyes.
Bones and Joints
- Hyper-mobile (over flexible) joints and/or stiff joints.
- Early joint disease leading to osteoarthritis and joint replacements at a younger age
- a full cleft, submucous or high arched palate and/or bifid uvula
- Micrognathia – where the lower jaw is shorter than the other resulting in poor contact between the chewing surfaces of the upper and lower teeth. These symptoms are similar to those found in Pierre Robin sequence (PRS). It is reported that 30% of children diagnosed with PRS are later re-diagnosed as having Stickler syndrome.
- Other facial characteristics include a flat face with a small nose and little or no nasal bridge. Appearance tends to improve with age
- Hearing loss ( sensorineural and or conductive. The degree varies in affected individuals and may become more severe over time.
- Glue ear in childhood caused by cleft palate.
These may include curvature of the spine (scoliosis), and because of sight and hearing problems, some learning difficulties may be experienced. Many people within the support group, especially children, complain of chronic fatigue.
NOTE: There is no cure for Stickler syndrome.
Management of the condition
Once Stickler syndrome is diagnosed, a co-ordinated multidisciplinary approach is desirable. This should include:
- Ophthalmic assessment. Due to the high risk of retinal detachment, all patients also require long-term follow up and are advised to seek ophthalmic help if they see new floaters or shadows in their vision.
- If there is evidence of midline clefting, a maxillo-facial assessment.
- Hearing tests and management of combined conductive and sensorineural deafness.
- Joint hypermobility should be assessed objectively using the Beighton scoring system to allow comparison with age, sex and race matched population.
- Rheumatological assessment and follow up is advised in older patients who may benefit from physiotherpy, arthropathy, or ultimately joint replacement surgery.
- Children should be educationally assessed. Although intelligence is normal, patients of school age may face considerable educational difficulties because of combined visual and auditory impairment.