Knobloch syndrome 2 is a rare hereditary disorder of the brain and eyes first described in 2011.
Only one patient with this syndrome, an 18 month old female infant, has been identified. The clinical features are similar to those of Knobloch Syndrome 1 to some extent with the skull defect, called an occipital encephalocele, near-sightedness, cataract, and retinal degeneration. This patient had poor vision which deteriorated during some years of follow-up and she developed a detachment of the retina. Her lenses also were displaced. Brain imaging did not reveal any abnormalities. The only additional findings were some delay fine motor movements.
This is an autosomal recessive condition that requires the presence of changes (mutations) in both copies of a specific gene. The parents of an affected individual which carry a single changed copy are clinically normal but confer a risk of 25% for Knobloch syndrome to each offspring.
The skull defect is usually visible at birth but sometimes can be subtle if only the overlying skin is involved. An ophthalmologist is needed to diagnose the ocular changes in this syndrome. While most retinal detachments can be repaired, such surgery is often unsuccessful in Knobloch syndrome.
The skull defect can be surgically closed and the cataracts/dislocated lenses can be removed.