CASK-Related Disorders

Title

Subtypes:

X-linked intellectual disability with or without nystagmus; X-linked intellectual disability, Najm type

Summary Summary

CASK-related disorders are a group of genetic disorders that affect brain development. The two main related disorders include microcephaly with pontine and cerebellar hypoplasia (MICPCH) and X-linked intellectual disability (XL-ID) with or without nystagmus. Males with these disorders usually have more severe symptoms than females. The signs and symptoms may include: autism spectrum disorders, intellectual disability, epilepsy disorders, seizures, a small head size (microcephaly) with specific brain findings (pontine and cerebellar hypoplasia), delayed growth, vision and hearing issues, and low muscle tone (hypotonia).^[1]^[2]

CASK-related disorders are caused by mutations in the CASK gene and are inherited in an X-linked manner.^[1] Some researchers have suggested that a condition called FG syndrome 4 may also be caused by mutations in the CASK gene, but it seems that the only family described with this syndrome may have actually had XL-ID, with or without nystagmus.^[3]^[2] Treatment is focused on alleviating symptoms and may include medication to control seizures, nutritional support, hearing and vision aids, and physical therapy. The best management usually requires a team of specialists.^[1]

Last updated: 3/17/2017

Symptoms Symptoms

The two main conditions in CASK-related disorders include microcephaly with pontine and cerebellar hypoplasia (MICPCH), and X-linked intellectual disability (XL-ID) with or without nystagmus. The signs and symptoms associated with each condition may overlap and males are usually more severely affected than females. Symptoms appear in infancy and typically progress over time.^[1]^[3]

The signs and symptoms found in people with MICPCH may include:^[1]^[2]

An unusually small head at birth (microcephaly) that does not grow at the same rate as the rest of the body
Underdevelopment (hypoplasia) of areas of the brain called the cerebellum and the pons
Intellectual disability, which is usually severe
Sleep disturbances
Repetitive behaviors including self-biting and hand flapping
Seizures
Vision problems, such as a small (hypoplastic) nerve in the eye (optic nerve), deterioration of the retina of the eye (retinopathy), and strabismus (crossed eyes)
Hearing loss caused by nerve problems in the inner ear (sensorineural deafness)
Decreased muscle tone (hypotonia) in the torso, increased muscle tone (hypertonia), and stiffness (spasticity) in the limbs
Movement problems such as involuntary tensing of various muscles (dystonia)

Individuals with MICPCH may also have a different types of epilepsy disorders including Ohtahara syndrome, West syndrome, and myoclonic epilepsy. These disorders are more common in males with MICPCH. Other findings may include unique facial features such as arched eyebrows; a short, broad nose; a lengthened area between the nose and mouth (philtrum); a protruding upper jaw (maxilla); a short chin; and large ears. People with MICPCH do not usually develop language skills, and most do not learn to walk.^[2]

X-linked intellectual disability (XL-ID) with or without nystagmus is typically a more mild condition with signs and symptoms that may include:^[1]^[2]

Rapid, involuntary eye movements (nystagmus)
Other eye findings such as strabismus and an abnormal coloration of the optic disc (optic disc pallor)
Mild to severe intellectual disability (some females having normal intelligence)
Seizures
Hypotonia
Rhythmic shaking (tremors)

One family with FG syndrome 4 (FGS4) was found to have mutations in the CASK gene, however, some researchers suggest that this family should be included under X-linked intellectual disability (XL-ID) with or without nystagmus.^[4]

Last updated: 3/17/2017

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
5%-29% of people have these symptoms
Macrogyria		0007227
Nystagmus	Involuntary, rapid, rhythmic eye movements	0000639
Optic disc pallor		0000543
Optic nerve hypoplasia		0000609
Scoliosis	Abnormal curving of the spine	0002650
Seizures	Seizure	0001250
Sensorineural hearing impairment		0000407
Strabismus	Cross-eyed Squint Squint eyes [ more ]	0000486
1%-4% of people have these symptoms
Feeding difficulties in infancy		0008872
Neonatal hypotonia	Low muscle tone, in neonatal onset	0001319
Prominent forehead	Pronounced forehead Protruding forehead [ more ]	0011220
Percent of people who have these symptoms is not available through HPO
Abnormally large globe	Increased size of eyes Large eyes [ more ]	0001090
Absent speech	Absent speech development Lack of language development Lack of speech No speech development No speech or language development Nonverbal [ more ]	0001344
Broad nasal tip	Broad tip of nose Broad, upturned nose Increased breadth of nasal tip Increased breadth of tip of nose Increased width of nasal tip Increased width of tip of nose Nasal tip, broad Nasal tip, wide Wide tip of nose [ more ]	0000455
Cerebellar hypoplasia	Small cerebellum Underdeveloped cerebellum [ more ]	0001321
Decreased body weight	Decreased weight Low body weight Low weight Weight less than 3rd percentile [ more ]	0004325
Dilated fourth ventricle		0002198
Epicanthus	Eye folds Prominent eye folds [ more ]	0000286
Generalized hypotonia	Decreased muscle tone Low muscle tone [ more ]	0001290
Global developmental delay		0001263
High palate	Elevated palate Increased palatal height [ more ]	0000218
Hyperreflexia	Increased reflexes	0001347
Hypertelorism	Wide-set eyes Widely spaced eyes [ more ]	0000316
Hypohidrosis	Decreased ability to sweat Decreased sweating Sweating, decreased [ more ]	0000966
Intellectual disability	Mental deficiency Mental retardation Mental retardation, nonspecific Mental-retardation [ more ]	0001249
Intellectual disability, moderate	IQ between 34 and 49	0002342
Long philtrum		0000343
Macrotia	Large ears	0000400
Micrognathia	Little lower jaw Small jaw Small lower jaw [ more ]	0000347
Muscle weakness	Muscular weakness	0001324
Muscular hypotonia of the trunk	Low muscle tone in trunk	0008936
Oval face	Oval facial shape	0000300
Postnatal growth retardation	Growth delay as children	0008897
Progressive microcephaly	Progressively abnormally small cranium Progressively abnormally small skull [ more ]	0000253
Prominent nasal bridge	Elevated nasal bridge High nasal bridge Prominent bridge of nose Prominent nasal root Protruding bridge of nose Protruding nasal bridge [ more ]	0000426
Short nose	Decreased length of nose Shortened nose [ more ]	0003196
Short stature	Decreased body height Small stature [ more ]	0004322
Spasticity	Involuntary muscle stiffness, contraction, or spasm	0001257
Wide nasal bridge	Broad nasal bridge Broad nasal root Broadened nasal bridge Increased breadth of bridge of nose Increased breadth of nasal bridge Increased width of bridge of nose Increased width of nasal bridge Nasal bridge broad Wide bridge of nose Widened nasal bridge [ more ]	0000431
X-linked dominant inheritance		0001423
X-linked inheritance		0001417

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

Last updated: 5/1/2019

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

Cause Cause

CASK-related disorders are caused by mutations in the CASK gene. This gene provides instructions for making the CASK protein, which is typically found in the nerve cells in the brain (neurons). The CASK protein is involved in controlling the activity of other genes that are involved in brain development and regulating the movement of certain necessary for signaling between neurons. Researchers suspected the protein may also be involved in development of the nerves that control eye movement.^[2]

Mutations in the CASK gene are thought to affect the role of the CASK protein in brain development and function, resulting in the associated signs and symptoms. Research indicates that the more severe symptoms associated with these disorders are caused by mutations that completely eliminate the function of the CASK protein, while more mild symptoms are caused by mutations that impair or reduce the function of the protein.^[1]^[2]

Last updated: 3/16/2017

Inheritance Inheritance

CASK-related disorders are inherited in an X-linked dominant manner.^[1] This means that the gene responsible for the condition is located on the X chromosome, and having only one mutated copy of the gene is enough to cause the condition.

Because males have only one X chromosome (and one Y chromosome) and females have two X chromosomes, X-linked dominant conditions affect males and females differently. Both males and females can have an X-linked dominant condition. However, because males don't have a second, working copy of the gene (as females do), they usually have more severe disease than females.

If a father has the mutated X-linked gene:

All of his daughters will inherit the mutated gene (they will all receive his X chromosome)
None of his sons will inherit the mutated gene (they only inherit his Y chromosome)

If a mother has the mutated X-linked gene, each of her children (both male and female) has a 50% chance to inherit the mutated gene.

Rather than being inherited from a parent, the condition may also be caused by a new mutation that occurs for the first time in an affected person (a de novo mutation).

Last updated: 3/16/2017

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.

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 CASK-Related Disorders. This website is maintained by the National Library of Medicine.

In-Depth Information

GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
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.
Online Mendelian Inheritance in Man (OMIM)
Online Mendelian Inheritance in Man (OMIM)

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Have a question? Contact a GARD Information Specialist.

References References

Moog U, Uyanik G, Kutsche K. CASK-Related Disorders. GeneReviews. November 26, 2013; https://www.ncbi.nlm.nih.gov/books/NBK169825/.
CASK-related intellectual disability. Genetics Home Reference. March 2014; https://ghr.nlm.nih.gov/condition/cask-related-intellectual-disability.
Srivastava S, McMillan R, Willis J, Clark H, Chavan V, Lian C, Zhang H, Hulver M, Mukherjee K. X-linked intellectual disability gene CASK regulates postnatal brain growth in a non-cell autonomous manner. Acta Neuropathol Commun. March 31, 2016; 4:30. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4818453/.
FG syndrome. Genetics Home Reference. December 2012; https://ghr.nlm.nih.gov/condition/fg-syndrome.