Introduction
Sticklers syndrome is a rare genetic disorder that is caused by the mutation of certain genes involved in the formation of proteins known as collagen. Collagen is the building block of many types of connective tissues that support the body's internal structures. The collagen that area affected by the stickler syndrome make up the cartilage which is the tissue that cushions bones with joints and the vitreous which is the jelly like fluid that fills the center of the eye. In most cases, stickler syndrome is passed on from the parents to the child but if one parent does not have stickler syndrome, the chances of the child contracting sticklers syndrome are 50%.
Types of stickler syndrome
There are four main types of sticklers syndrome and each of them is identified depending on the inheritance pattern and the location of the mutated gene.
- Sticklers syndrome type 1: It is the most popular stickler condition. It affects the eyes, joints, jaw, ears and cleft and is caused by the nmutation of a gene known as COLA21. The inheritance pattern fro this type of stickler syndrome is autosomal dominant.
- Sticklers syndrome type 2: It is caused by the mutation of COL11A1 gene on the chromosome 1p21. Its inheritance pattern is autosomal dominant.
- Sticklers syndrome type 3: It mainly affects the joints and ears but does not affect the eyes. It is caused by the mutation of COL11A2 gene on the chromosome 6p21.3. Its inheritance pattern is autosomal dominant.
- Sticklers syndrome type 4: It is caused by mutation in the gene COL9A1 that is located on the 6q13 chromosome. Its inheritance pattern is autosomal recessive.
Causes of stickler syndrome
Sticklers syndrome is caused by mutations of certain genes that are responsible for the formation of proteins known as collagen. Sticklers syndrome can be hereditary where it is passed from the parents to the child. However, in some cases, sticklers can develop on its own due to low amounts or defective collagen molecules. A metabolic defect that affects the hyaluronic acid and the 2-d type collagen is also a known cause of stickler syndrome.
Symptoms of stickler syndrome
The signs and symptoms of sticklers syndrome tend to vary from one individual to another depending on the severity of the disease. The following are the main symptoms of sticklers syndrome.
- Altered facial features: People suffering from sticklers tend to have a flattened face with a small nose, a recessed nasal bridge and a foreshortened chin.
- Pierre robin sequence: Most people with stickler have birth defects that make breathing and feeding difficult. This combination of birth defects is known as Pierre robin defects and includes a small jaw, a tongue that falls back to the throat and a cleft palate.
- Hearing difficulties: The severity of this varies among people with stickler syndrome. It affects the ability to hear high frequencies and it worsens with time.
- Eye problems: Children suffering from stickler experience a lot of eye problems most of which are associated with older people. These eye problems include;
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- Cataract - Some children are born with cataract which is a clouding of the focusing lens within the eye. Some develop cataract later in life.
- Severe nearsightedness - Most children with stickler syndrome are born with this defect which is a disorder of the vision where the affected person can see near objects clearly and far objects appear to be blurry.
- Retinal detachments - These are problems associated with the retina which is crucial for proper vision hence blindness can occur at some point if the retina pulls away from the back of the eyeball.
- Glaucoma - This causes pressure in the eye to increase leading to the damage of the optic nerve.
5. Bone and joint abnormalities:
- Long fingers – People suffering from sticklers have long fingers with enlarged knuckles.
- Osteoarthritis – This is premature arthritis that starts in childhood.
- Excessive joint flexibility – People who suffer from stickler are able to extend their joints beyond the normal range. This ability tends to lessen with age.
- Scoliosis – This is the abnormal curvatures of the spine. Children with stickler should be monitored for the development of this disorder so that early treatment can be administered.
