Knobloch syndrome

Title

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Other Names:

Myopia retinal detachment encephalocele; Knobloch-Layer syndrome; Retinal detachment-occipital encephalocele syndrome

Categories:

Congenital and Genetic Diseases; Eye diseases

Summary Summary

Knobloch syndrome is characterized by severe vision problems and skull defects.^[1] The most common features include extreme nearsightedness (high myopia), recurrent retinal detachment, and occipital encephalocele.^[1]^[2] There are three types of Knobloch syndrome, which can be distinguished by the underlying genetic cause. Knobloch syndrome type I is caused by mutations in the COL18A1 gene. The genes associated with Knobloch syndrome type 2 and type 3 have not been identified; however, Knobloch syndrome type 3 has been linked to a specific region on chromosome 17, known as 17q11.2.^[2]^[3] Knobloch syndrome follows an autosomal recessive pattern of inheritance.^[1]^[2]^[3] Treatment is aimed at addressing the symptoms present in each individual and may include surgery to repair retinal detachments and occiptal encephaloceles.^[3]

Last updated: 10/18/2016

Symptoms Symptoms

The three main features of Knobloch syndrome are severe nearsightedness (high myopia), recurrent retinal detachment, and occipital encephalocele.^[1]^[2]^[3] The severe myopia develops early on in life, and is usually diagnosed within the first year. Affected individuals may have additional eye abnormalities, such as congenital cataracts, iris abnormalities, and lens subluxation (when the lens of the eye drifts off-center). An encephalocele is a sac-like protrusion of the brain through an opening in the base of the skull (the occipital bone). A variety of other signs and symptoms have been described in affected individuals. Intelligence is not affected by Knobloch syndrome.^[3]

Last updated: 10/18/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms	Other Names	Learn More: HPO ID
80%-99% of people have these symptoms
Calvarial skull defect	Cranial defect Skull defect [ more ]	0001362
Macular degeneration		0000608
Myopia	Close sighted Near sighted Near sightedness Nearsightedness [ more ]	0000545
Occipital encephalocele	Brain tissue sticks out through back of skull	0002085
Retinal detachment	Detached retina	0000541
30%-79% of people have these symptoms
Hydrocephalus	Too much cerebrospinal fluid in the brain	0000238
Nystagmus	Involuntary, rapid, rhythmic eye movements	0000639
Progressive visual loss	Progressive loss of vision Progressive vision loss Progressive visual impairment Slowly progressive visual loss Vision loss, progressive Visual loss, progressive [ more ]	0000529
Vitreoretinopathy		0007773
5%-29% of people have these symptoms
Abnormal hair morphology	Abnormality of the hair Hair abnormality [ more ]	0001595
Bifid ureter		0030037
Cataract	Clouding of the lens of the eye Cloudy lens [ more ]	0000518
Depressed nasal bridge	Depressed bridge of nose Flat bridge of nose Flat nasal bridge Flat, nasal bridge Flattened nasal bridge Low nasal bridge Low nasal root [ more ]	0005280
Dextrocardia	Heart tip and four chambers point towards right side of body	0001651
Ectopia lentis		0001083
Epicanthus	Eye folds Prominent eye folds [ more ]	0000286
Joint hyperflexibility	Joints move beyond expected range of motion	0005692
Lymphangioma		0100764
Mental deterioration	Cognitive decline Cognitive decline, progressive Intellectual deterioration Progressive cognitive decline [ more ]	0001268
Midface retrusion	Decreased size of midface Midface deficiency Underdevelopment of midface [ more ]	0011800
Patent ductus arteriosus		0001643
Pyloric stenosis		0002021
Seizure		0001250
Strabismus	Cross-eyed Squint Squint eyes [ more ]	0000486
Vesicoureteral reflux		0000076
Percent of people who have these symptoms is not available through HPO
Alopecia	Hair loss	0001596
Ataxia		0001251
Autosomal recessive inheritance		0000007
Band keratopathy		0000585
Cerebellar atrophy	Degeneration of cerebellum	0001272
Cerebral atrophy	Degeneration of cerebrum	0002059
Developmental cataract	Clouding of the lens of the eye at birth	0000519
High myopia	Severe near sightedness Severely close sighted Severely near sighted [ more ]	0011003
Macular hypoplasia		0001104
Peripapillary atrophy		0500087
Phthisis bulbi		0000667
Polymicrogyria	More grooves in brain	0002126
Ventriculomegaly		0002119
Visual loss	Loss of vision Vision loss [ more ]	0000572

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Do you have more information about symptoms of this disease? We want to hear from you.

Last updated: 1/1/2021

Do you have updated information on this disease? We want to hear from you.

Cause Cause

Some cases of Knobloch syndrome are caused by mutations in the COL18A1 gene.^[1]^[2]^[3] 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.^[1] 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.^[2]^[3]

Last updated: 10/18/2016

Inheritance Inheritance

Knobloch syndrome has an autosomal recessive pattern of inheritance, which means that both copies of the gene in each cell have mutations.^[1]^[2]^[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.^[1] When 2 carriers of an autosomal recessive condition have children, each cild has a:

25% chance to be affected
50% chance to be an unaffected carrier like each parent
25% chance to be unaffected and not a carrier

Last updated: 10/18/2016

Find a Specialist Find a Specialist

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.

Related Diseases Related Diseases

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
The differential diagnosis should include the following syndromes: Stickler, Wagner, Marshall, Meckel and HARD±E syndrome (see these terms). Visit the Orphanet disease page for more information.

Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Foundation Fighting Blindness
7168 Columbia Gateway Drive, Suite 100
Columbia, MD 21046
Toll-free: 1-800-683-5555
Telephone: +1-410-423-0600
TTY: 1-800-683-5551
E-mail: info@fightblindness.org
Website: https://www.fightingblindness.org/

Social Networking Websites

Visit the following Facebook groups related to Knobloch syndrome:
Humans with Knobloch Syndrome Resource & Support Group

Organizations Providing General Support

National Alliance for Eye and Vision Research (NAEVR)
5515 Security Lane
Suite 500
Rockville, MD 20852
Telephone: +1-240-221-2905
E-mail: jamesj@eyeresearch.org
Website: https://www.eyeresearch.org/
Retina International
Suite 108, Camden Business Centre
12 Camden Row
Dublin 8
Ireland
Telephone: +353 1 472 0468
E-mail: avril.daly@retina-International.org
Website: https://www.retina-international.org/

Do you know of an organization? We want to hear from you.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

Genetics Home Reference (GHR) contains information on Knobloch syndrome. This website is maintained by the National Library of Medicine.

In-Depth Information

The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Knobloch syndrome. Click on the link to view a sample search on this topic.

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