Stickler’s syndrome is caused by a mutation of four genes: COL2A1, COL11A1, COL9A1, and COL11A2. These genes provide the complete instructions for the production of collagen, the major protein component of connective tissues in the body. The genes encode three types of collagen: type XI, type IX, and type II. These are important components of sclera, cornea, vitreous humour, and cartilage. Mutation of COL2A1, COL11A1, COL9A1, and COL11A2 results to the production of defective collagens that cannot function properly, which can lead to abnormalities in body parts where collagen is found such as the eyes, bones, joints, ear and facial bones.
Stickler’s syndrome is inherited in an autosomal dominant manner if the genes involved are COL2A1, COL11A1, and COL11A2. In this manner of inheritance, just one copy of the mutant gene from either the mother or father will cause the disorder. An affected person has a 50 percent chance of passing on the mutant gene to each child.
Stickler’s syndrome due to COL9A1 mutation is inherited through autosomal recessive manner. Two copies of the mutant gene from both the mother and father are needed to cause the disorder.