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COACH syndrome 2(COACH2)

MedGen UID:
1752166
Concept ID:
C5436837
Disease or Syndrome
Synonyms: COACH SYNDROME 2; COACH2
 
Gene (location): CC2D2A (4p15.32)
 
Monarch Initiative: MONDO:0030859
OMIM®: 619111

Definition

COACH syndrome is classically defined as Cerebellar vermis hypoplasia, Oligophrenia, Ataxia, Colobomas, and Hepatic fibrosis (Verloes and Lambotte, 1989). Brain MRI demonstrates the molar tooth sign, which is a feature of Joubert syndrome. The disorder has been described as a Joubert syndrome-related disorder with liver disease (summary by Doherty et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of COACH syndrome, see 216360. [from OMIM]

Clinical features

From HPO
Hyperechogenic kidneys
MedGen UID:
477530
Concept ID:
C3275899
Finding
An increase in amplitude of waves returned in ultrasonography of the kidney, which is generally displayed as increased brightness of the signal.
Hypertensive disorder
MedGen UID:
6969
Concept ID:
C0020538
Disease or Syndrome
The presence of chronic increased pressure in the systemic arterial system.
Congenital hepatic fibrosis
MedGen UID:
40449
Concept ID:
C0009714
Disease or Syndrome
Congenital hepatic fibrosis is a disease of the liver that is present from birth. The liver has many important functions, including producing various substances needed by the body and breaking down other substances into smaller parts to be used or removed from the body.\n\nCongenital hepatic fibrosis is characterized by abnormal formation of the bile ducts and the blood vessels of the hepatic portal system. Bile ducts carry bile (a fluid that helps to digest fats) from the liver to the gallbladder and small intestine. The hepatic portal system is a branching network of veins (portal veins) that carry blood from the gastrointestinal tract to the liver for processing.\n\nA buildup of scar tissue (fibrosis) in the portal tracts also occurs in this disorder. Portal tracts are structures in the liver that bundle the vessels through which blood, lymph, and bile flow. Lymph is a fluid that helps exchange immune cells, proteins, and other substances between the blood and tissues. Fibrosis in the portal tracts can restrict the normal movement of fluids in these vessels.\n\nNarrowing of the portal veins due to malformation and portal tract fibrosis results in high blood pressure in the hepatic portal system (portal hypertension). Portal hypertension impairs the flow of blood from the gastrointestinal tract, causing an increase in pressure in the veins of the esophagus, stomach, and intestines. These veins may stretch and their walls may become thin, leading to a risk of abnormal bleeding.\n\nPeople with congenital hepatic fibrosis have an enlarged liver and spleen (hepatosplenomegaly). The liver is also abnormally shaped. Affected individuals also have an increased risk of infection of the bile ducts (cholangitis), hard deposits in the gallbladder or bile ducts (gallstones), and cancer of the liver or gallbladder.\n\nCongenital hepatic fibrosis may occur alone, in which case it is called isolated congenital hepatic fibrosis. More frequently, it occurs as a feature of genetic syndromes that also affect the kidneys, such as polycystic kidney disease (PKD).
Hepatic fibrosis
MedGen UID:
116093
Concept ID:
C0239946
Disease or Syndrome
The presence of excessive fibrous connective tissue in the liver. Fibrosis is a reparative or reactive process.
Portal fibrosis
MedGen UID:
893107
Concept ID:
C3805083
Disease or Syndrome
Fibroblast proliferation and fiber expansion from the portal areas to the lobule.
Hydrocephalus
MedGen UID:
9335
Concept ID:
C0020255
Disease or Syndrome
Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.
Corpus callosum, agenesis of
MedGen UID:
104498
Concept ID:
C0175754
Congenital Abnormality
The corpus callosum is the largest fiber tract in the central nervous system and the major interhemispheric fiber bundle in the brain. Formation of the corpus callosum begins as early as 6 weeks' gestation, with the first fibers crossing the midline at 11 to 12 weeks' gestation, and completion of the basic shape by age 18 to 20 weeks (Schell-Apacik et al., 2008). Agenesis of the corpus callosum (ACC) is one of the most frequent malformations in brain with a reported incidence ranging between 0.5 and 70 in 10,000 births. ACC is a clinically and genetically heterogeneous condition, which can be observed either as an isolated condition or as a manifestation in the context of a congenital syndrome (see MOLECULAR GENETICS and Dobyns, 1996). Also see mirror movements-1 and/or agenesis of the corpus callosum (MRMV1; 157600). Schell-Apacik et al. (2008) noted that there is confusion in the literature regarding radiologic terminology concerning partial absence of the corpus callosum, where various designations have been used, including hypogenesis, hypoplasia, partial agenesis, or dysgenesis.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Cerebellar vermis hypoplasia
MedGen UID:
333548
Concept ID:
C1840379
Finding
Underdevelopment of the vermis of cerebellum.
Molar tooth sign on MRI
MedGen UID:
400670
Concept ID:
C1865060
Finding
An abnormal appearance of the midbrain in axial magnetic resonance imaging in which the elongated superior cerebellar peduncles give the midbrain an appearance reminiscent of a molar or wisdom tooth.
Oculomotor apraxia
MedGen UID:
483686
Concept ID:
C3489733
Disease or Syndrome
Ocular motor apraxia is a deficiency in voluntary, horizontal, lateral, fast eye movements (saccades) with retention of slow pursuit movements. The inability to follow objects visually is often compensated by head movements. There may be decreased smooth pursuit, and cancelation of the vestibulo-ocular reflex.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Apneic episodes in infancy
MedGen UID:
814310
Concept ID:
C3807980
Finding
Recurrent episodes of apnea occurring during infancy.
Elevated circulating hepatic transaminase concentration
MedGen UID:
116013
Concept ID:
C0235996
Finding
Elevations of the levels of SGOT and SGPT in the serum. SGOT (serum glutamic oxaloacetic transaminase) and SGPT (serum glutamic pyruvic transaminase) are transaminases primarily found in the liver and heart and are released into the bloodstream as the result of liver or heart damage. SGOT and SGPT are used clinically mainly as markers of liver damage.
Elevated circulating creatinine concentration
MedGen UID:
148579
Concept ID:
C0700225
Finding
An increased amount of creatinine in the blood.
Congenital ocular coloboma
MedGen UID:
1046
Concept ID:
C0009363
Congenital Abnormality
Coloboma is an eye abnormality that occurs before birth. Colobomas are missing pieces of tissue in structures that form the eye. They may appear as notches or gaps in one of several parts of the eye, including the colored part of the eye called the iris; the retina, which is the specialized light-sensitive tissue that lines the back of the eye; the blood vessel layer under the retina called the choroid; or the optic nerves, which carry information from the eyes to the brain.\n\nColobomas may be present in one or both eyes and, depending on their size and location, can affect a person's vision. Colobomas affecting the iris, which result in a "keyhole" appearance of the pupil, generally do not lead to vision loss. Colobomas involving the retina result in vision loss in specific parts of the visual field. Large retinal colobomas or those affecting the optic nerve can cause low vision, which means vision loss that cannot be completely corrected with glasses or contact lenses.\n\nSome people with coloboma also have a condition called microphthalmia. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in these cases some remaining eye tissue is generally present. Such severe microphthalmia should be distinguished from another condition called anophthalmia, in which no eyeball forms at all. However, the terms anophthalmia and severe microphthalmia are often used interchangeably. Microphthalmia may or may not result in significant vision loss.\n\nPeople with coloboma may also have other eye abnormalities, including clouding of the lens of the eye (cataract), increased pressure inside the eye (glaucoma) that can damage the optic nerve, vision problems such as nearsightedness (myopia), involuntary back-and-forth eye movements (nystagmus), or separation of the retina from the back of the eye (retinal detachment).\n\nColobomas involving the eyeball should be distinguished from gaps that occur in the eyelids. While these eyelid gaps are also called colobomas, they arise from abnormalities in different structures during early development.\n\nSome individuals have coloboma as part of a syndrome that affects other organs and tissues in the body. These forms of the condition are described as syndromic. When coloboma occurs by itself, it is described as nonsyndromic or isolated.
Strabismus
MedGen UID:
21337
Concept ID:
C0038379
Disease or Syndrome
A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.
Chorioretinal coloboma
MedGen UID:
66820
Concept ID:
C0240896
Congenital Abnormality
Absence of a region of the retina, retinal pigment epithelium, and choroid.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  

Professional guidelines

PubMed

Tang X, Liu C, Liu X, Chen J, Fan X, Liu J, Ma D, Cao G, Chen Z, Xu D, Zhu Y, Jiang X, Cheng L, Wu Y, Hou L, Li Y, Shao X, Zheng S, Zhang A, Zheng B, Jian S, Rong Z, Su Q, Gao X, Rao J, Shen Q, Xu H; Chinese Children Genetic Kidney Disease Database (CCGKDD); “Internet Plus” Nephrology Alliance of the National Center for Children’s Care
J Med Genet 2022 Feb;59(2):147-154. Epub 2020 Dec 15 doi: 10.1136/jmedgenet-2020-107184. PMID: 33323469

Recent clinical studies

Etiology

Tang X, Liu C, Liu X, Chen J, Fan X, Liu J, Ma D, Cao G, Chen Z, Xu D, Zhu Y, Jiang X, Cheng L, Wu Y, Hou L, Li Y, Shao X, Zheng S, Zhang A, Zheng B, Jian S, Rong Z, Su Q, Gao X, Rao J, Shen Q, Xu H; Chinese Children Genetic Kidney Disease Database (CCGKDD); “Internet Plus” Nephrology Alliance of the National Center for Children’s Care
J Med Genet 2022 Feb;59(2):147-154. Epub 2020 Dec 15 doi: 10.1136/jmedgenet-2020-107184. PMID: 33323469
Brancati F, Iannicelli M, Travaglini L, Mazzotta A, Bertini E, Boltshauser E, D'Arrigo S, Emma F, Fazzi E, Gallizzi R, Gentile M, Loncarevic D, Mejaski-Bosnjak V, Pantaleoni C, Rigoli L, Salpietro CD, Signorini S, Stringini GR, Verloes A, Zabloka D, Dallapiccola B, Gleeson JG, Valente EM; International JSRD Study Group
Hum Mutat 2009 Feb;30(2):E432-42. doi: 10.1002/humu.20924. PMID: 19058225Free PMC Article

Diagnosis

Tang X, Liu C, Liu X, Chen J, Fan X, Liu J, Ma D, Cao G, Chen Z, Xu D, Zhu Y, Jiang X, Cheng L, Wu Y, Hou L, Li Y, Shao X, Zheng S, Zhang A, Zheng B, Jian S, Rong Z, Su Q, Gao X, Rao J, Shen Q, Xu H; Chinese Children Genetic Kidney Disease Database (CCGKDD); “Internet Plus” Nephrology Alliance of the National Center for Children’s Care
J Med Genet 2022 Feb;59(2):147-154. Epub 2020 Dec 15 doi: 10.1136/jmedgenet-2020-107184. PMID: 33323469
Doherty D, Parisi MA, Finn LS, Gunay-Aygun M, Al-Mateen M, Bates D, Clericuzio C, Demir H, Dorschner M, van Essen AJ, Gahl WA, Gentile M, Gorden NT, Hikida A, Knutzen D, Ozyurek H, Phelps I, Rosenthal P, Verloes A, Weigand H, Chance PF, Dobyns WB, Glass IA
J Med Genet 2010 Jan;47(1):8-21. Epub 2009 Jul 1 doi: 10.1136/jmg.2009.067249. PMID: 19574260Free PMC Article
Gleeson JG, Keeler LC, Parisi MA, Marsh SE, Chance PF, Glass IA, Graham JM Jr, Maria BL, Barkovich AJ, Dobyns WB
Am J Med Genet A 2004 Mar 1;125A(2):125-34; discussion 117. doi: 10.1002/ajmg.a.20437. PMID: 14981712
Kumar S, Rankin R
Am J Med Genet 1996 Jan 11;61(2):122-6. doi: 10.1002/(SICI)1096-8628(19960111)61:2<122::AID-AJMG3>3.0.CO;2-Z. PMID: 8669436

Clinical prediction guides

Tang X, Liu C, Liu X, Chen J, Fan X, Liu J, Ma D, Cao G, Chen Z, Xu D, Zhu Y, Jiang X, Cheng L, Wu Y, Hou L, Li Y, Shao X, Zheng S, Zhang A, Zheng B, Jian S, Rong Z, Su Q, Gao X, Rao J, Shen Q, Xu H; Chinese Children Genetic Kidney Disease Database (CCGKDD); “Internet Plus” Nephrology Alliance of the National Center for Children’s Care
J Med Genet 2022 Feb;59(2):147-154. Epub 2020 Dec 15 doi: 10.1136/jmedgenet-2020-107184. PMID: 33323469

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