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Genetic and Rare Diseases Information Center (GARD)

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Knobloch syndrome

Other Names for this Disease
  • Myopia retinal detachment encephalocele
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Your Question

How did Knobloch syndrome get its name? Is severe myopia one of the main symptoms?

Our Answer

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What is Knobloch syndrome?

Knobloch syndrome is characterized by severe nearsightedness (myopia), recurrent retinal detachment, and encephalocele. This condition has an autosomal recessive pattern of inheritance. There are three types of Knobloch syndrome, which can be distinguished by the underlying genetic cause. The condition is called Knobloch syndrome type I when it is caused by mutations in the COL18A1 gene. The genes associated with Knobloch syndrome type II and type III have not been identified; however, Knobloch syndrome type III has been linked to a specific region on chromosome 17, known as 17q11.2.[1]
Last updated: 4/5/2010

How did Knobloch syndrome get its name?

Knobloch syndrome is named after one of the authors who first published an article on this condition. In 1971, a family was described by W.H. Knobloch and J.M. Layer in which 5 of 10 siblings had severe nearsightedness (myopia), recurrent retinal detachment, and encephalocele.[2] All the affected siblings had normal intelligence. The parents were unaffected and not related to one another.[1]
Last updated: 4/5/2010

What are the signs and symptoms of Knobloch syndrome?

The three main features of Knobloch syndrome are severe nearsightedness (myopia), recurrent retinal detachment, and encephalocele. The severe myopia develops early on in life, and it is usually diagnosed within the first year of life. Affected individuals may have additional eye abnormalities, such as congenital cataracts. An encephalocele is a sac-like protrusion of the brain through an opening in the skull. A variety of other signs and symptoms have been described in affected individuals. Intelligence is not affected by Knobloch syndrome.[3]
Last updated: 4/5/2010

What causes Knobloch syndrome?

Some cases of Knobloch syndrome are caused by mutations in the COL18A1 gene.[1] This gene provides instructions for making a protein that is used to assemble type XVIII collagen. Collagens are a family of proteins that strengthen and support connective tissues, such as skin, bone, tendons, and ligaments, throughout the body. The condition has also been linked to a specific region on chromosome 17, known as 17q11.2. However, researchers have not determined which gene in this region is associated with Knobloch syndrome.[4]
Last updated: 4/5/2010

How is Knoblch syndrome inherited?

Knobloch syndrome has an autosomal recessive pattern of inheritance, which means that both copies of the gene in each cell have mutations.[3] The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they do not show signs and symptoms of the condition. Autosomal recessive disorders are typically not seen in every generation of an affected family.
Last updated: 4/5/2010