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Cerebellar ataxia, brain abnormalities, and cardiac conduction defects(CABAC)

MedGen UID:
1794215
Concept ID:
C5562005
Disease or Syndrome
Synonyms: CABAC; CEREBELLAR ATAXIA, BRAIN ABNORMALITIES, AND CARDIAC CONDUCTION DEFECTS
 
Gene (location): EXOSC5 (19q13.2)
 
Monarch Initiative: MONDO:0859200
OMIM®: 619576

Definition

Cerebellar ataxia, brain abnormalities, and cardiac conduction defects (CABAC) is an autosomal recessive primarily neurologic disorder with variable manifestations. Common features included infantile-onset hypotonia, poor motor development, poor feeding and overall growth, and ataxic gait due to cerebellar ataxia. Other features include dysarthria, nystagmus, variable ocular anomalies, spasticity, hyperreflexia, and nonspecific dysmorphic features. Most, but not all, patients have global developmental delay with impaired intellectual development and speech delay. Brain imaging shows cerebellar hypoplasia, often with brainstem hypoplasia, enlarged ventricles, delayed myelination, and thin corpus callosum. A significant number of patients develop cardiac conduction defects in childhood or adolescence, often requiring pacemaker placement (summary by Slavotinek et al., 2020). [from OMIM]

Clinical features

From HPO
Tapered finger
MedGen UID:
98098
Concept ID:
C0426886
Finding
The gradual reduction in girth of the finger from proximal to distal.
Clinodactyly
MedGen UID:
1644094
Concept ID:
C4551485
Congenital Abnormality
An angulation of a digit at an interphalangeal joint in the plane of the palm (finger) or sole (toe).
Mitral regurgitation
MedGen UID:
7670
Concept ID:
C0026266
Disease or Syndrome
An abnormality of the mitral valve characterized by insufficiency or incompetence of the mitral valve resulting in retrograde leaking of blood through the mitral valve upon ventricular contraction.
Tricuspid regurgitation
MedGen UID:
11911
Concept ID:
C0040961
Disease or Syndrome
Failure of the tricuspid valve to close sufficiently upon contraction of the right ventricle, causing blood to regurgitate (flow backward) into the right atrium.
Right bundle branch block
MedGen UID:
88445
Concept ID:
C0085615
Disease or Syndrome
A conduction block of the right branch of the bundle of His. This manifests as a prolongation of the QRS complex (greater than 0.12 s) with delayed activation of the right ventricle and terminal delay on the EKG.
Short stature
MedGen UID:
87607
Concept ID:
C0349588
Finding
A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).
Growth delay
MedGen UID:
99124
Concept ID:
C0456070
Pathologic Function
A deficiency or slowing down of growth pre- and postnatally.
Dysphagia
MedGen UID:
41440
Concept ID:
C0011168
Disease or Syndrome
Difficulty in swallowing.
Feeding difficulties
MedGen UID:
65429
Concept ID:
C0232466
Finding
Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.
Cerebellar ataxia
MedGen UID:
849
Concept ID:
C0007758
Disease or Syndrome
Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).
Dysarthria
MedGen UID:
8510
Concept ID:
C0013362
Mental or Behavioral Dysfunction
Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.
Leukodystrophy
MedGen UID:
6070
Concept ID:
C0023520
Disease or Syndrome
Leukodystrophy refers to deterioration of white matter of the brain resulting from degeneration of myelin sheaths in the CNS. Their basic defect is directly related to the synthesis and maintenance of myelin membranes. Symmetric white matter involvement at MRI is a typical finding in patients with leukodystrophies.
Spasticity
MedGen UID:
7753
Concept ID:
C0026838
Sign or Symptom
A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.
Hyperreflexia
MedGen UID:
57738
Concept ID:
C0151889
Finding
Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.
Orofacial dyskinesia
MedGen UID:
57747
Concept ID:
C0152115
Disease or Syndrome
Syndromes which feature dyskinesias as a cardinal manifestation of the disease process. Included in this category are degenerative, hereditary, post-infectious, medication-induced, post-inflammatory, and post-traumatic conditions.
Dysmetria
MedGen UID:
68583
Concept ID:
C0234162
Finding
A type of ataxia characterized by the inability to carry out movements with the correct range and motion across the plane of more than one joint related to incorrect estimation of the distances required for targeted movements.
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.
Inability to walk
MedGen UID:
107860
Concept ID:
C0560046
Finding
Incapability to ambulate.
Cerebellar atrophy
MedGen UID:
196624
Concept ID:
C0740279
Disease or Syndrome
Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.
Absent speech
MedGen UID:
340737
Concept ID:
C1854882
Finding
Complete lack of development of speech and language abilities.
Intellectual disability, profound
MedGen UID:
892508
Concept ID:
C3161330
Mental or Behavioral Dysfunction
Profound mental retardation is defined as an intelligence quotient (IQ) below 20.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Subnormal intellectual functioning which originates during the developmental period. Intellectual disability, previously referred to as mental retardation, has been defined as an IQ score below 70.
CNS hypomyelination
MedGen UID:
892446
Concept ID:
C4025616
Finding
Reduced amount of myelin in the central nervous system resulting from defective myelinogenesis.
Myoclonic seizure
MedGen UID:
1385980
Concept ID:
C4317123
Sign or Symptom
A myoclonic seizure is a type of motor seizure characterised by sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus.
Cerebral cortical atrophy
MedGen UID:
1646740
Concept ID:
C4551583
Disease or Syndrome
Atrophy of the cortex of the cerebrum.
Pachygyria
MedGen UID:
504794
Concept ID:
CN001193
Finding
Pachygyria is a malformation of cortical development with abnormally wide gyri with sulci 1,5-3 cm apart and abnormally thick cortex measuring more than 5 mm (radiological definition). See also neuropathological definitions for 2-, 3-, and 4-layered lissencephaly.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Retrognathia
MedGen UID:
19766
Concept ID:
C0035353
Congenital Abnormality
An abnormality in which the mandible is mislocalised posteriorly.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Muscle weakness
MedGen UID:
57735
Concept ID:
C0151786
Finding
Reduced strength of muscles.
Camptodactyly
MedGen UID:
195780
Concept ID:
C0685409
Congenital Abnormality
The distal interphalangeal joint and/or the proximal interphalangeal joint of the fingers or toes cannot be extended to 180 degrees by either active or passive extension.
Generalized hypotonia
MedGen UID:
346841
Concept ID:
C1858120
Finding
Generalized muscular hypotonia (abnormally low muscle tone).
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Wide mouth
MedGen UID:
44238
Concept ID:
C0024433
Congenital Abnormality
Distance between the oral commissures more than 2 SD above the mean. Alternatively, an apparently increased width of the oral aperture (subjective).
Mandibular prognathia
MedGen UID:
98316
Concept ID:
C0399526
Finding
Abnormal prominence of the chin related to increased length of the mandible.
Prominent nose
MedGen UID:
98423
Concept ID:
C0426415
Finding
Distance between subnasale and pronasale more than two standard deviations above the mean, or alternatively, an apparently increased anterior protrusion of the nasal tip.
Deviated nasal septum
MedGen UID:
154288
Concept ID:
C0549397
Finding
Positioning of the nasal septum to the right or left in contrast to the normal midline position of the nasal septum.
Thick vermilion border
MedGen UID:
332232
Concept ID:
C1836543
Finding
Increased width of the skin of vermilion border region of upper lip.
Tooth malposition
MedGen UID:
377692
Concept ID:
C1852504
Finding
Abnormal alignment, positioning, or spacing of the teeth, i.e., misaligned teeth.
Prominent nasal bridge
MedGen UID:
343051
Concept ID:
C1854113
Finding
Anterior positioning of the nasal root in comparison to the usual positioning for age.
Sloping forehead
MedGen UID:
346640
Concept ID:
C1857679
Finding
Inclination of the anterior surface of the forehead from the vertical more than two standard deviations above the mean (objective); or apparently excessive posterior sloping of the forehead in a lateral view.
Astigmatism
MedGen UID:
2473
Concept ID:
C0004106
Disease or Syndrome
Astigmatism (from the Greek 'a' meaning absence and 'stigma' meaning point) is a condition in which the parallel rays of light entering the eye through the refractive media are not focused on a single point. Both corneal and noncorneal factors contribute to refractive astigmatism. Corneal astigmatism is mainly the result of an aspheric anterior surface of the cornea, which can be measured readily by means of a keratometer; in a small fraction of cases (approximately 1 in 10) the effect is neutralized by the back surface. The curvature of the back surface of the cornea is not considered in most studies, because it is more difficult to measure; moreover, in the case of severe corneal astigmatism, there is evidence that both surfaces have the same configuration. Noncorneal factors are errors in the curvature of the 2 surfaces of the crystalline lens, irregularity in the refractive index of the lens, and an eccentric lens position. Since the cornea is the dominant component of the eye's refracting system, a highly astigmatic cornea is likely to result in a similarly astigmatic ocular refraction (summary by Clementi et al., 1998).
Esotropia
MedGen UID:
4550
Concept ID:
C0014877
Disease or Syndrome
A form of strabismus with one or both eyes turned inward ('crossed') to a relatively severe degree, usually defined as 10 diopters or more.
Myopia
MedGen UID:
44558
Concept ID:
C0027092
Disease or Syndrome
Nearsightedness, also known as myopia, is an eye condition that causes blurry distance vision. People who are nearsighted have more trouble seeing things that are far away (such as when driving) than things that are close up (such as when reading or using a computer). If it is not treated with corrective lenses or surgery, nearsightedness can lead to squinting, eyestrain, headaches, and significant visual impairment.\n\nNearsightedness usually begins in childhood or adolescence. It tends to worsen with age until adulthood, when it may stop getting worse (stabilize). In some people, nearsightedness improves in later adulthood.\n\nFor normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. People who are nearsighted typically have eyeballs that are too long from front to back. As a result, light entering the eye is focused too far forward, in front of the retina instead of on its surface. It is this change that causes distant objects to appear blurry. The longer the eyeball is, the farther forward light rays will be focused and the more severely nearsighted a person will be.\n\nNearsightedness is measured by how powerful a lens must be to correct it. The standard unit of lens power is called a diopter. Negative (minus) powered lenses are used to correct nearsightedness. The more severe a person's nearsightedness, the larger the number of diopters required for correction. In an individual with nearsightedness, one eye may be more nearsighted than the other.\n\nEye doctors often refer to nearsightedness less than -5 or -6 diopters as "common myopia." Nearsightedness of -6 diopters or more is commonly called "high myopia." This distinction is important because high myopia increases a person's risk of developing other eye problems that can lead to permanent vision loss or blindness. These problems include tearing and detachment of the retina, clouding of the lens (cataract), and an eye disease called glaucoma that is usually related to increased pressure within the eye. The risk of these other eye problems increases with the severity of the nearsightedness. The term "pathological myopia" is used to describe cases in which high myopia leads to tissue damage within the eye.
Optic atrophy
MedGen UID:
18180
Concept ID:
C0029124
Disease or Syndrome
Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.
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.
Horizontal nystagmus
MedGen UID:
124399
Concept ID:
C0271385
Disease or Syndrome
Nystagmus consisting of horizontal to-and-fro eye movements.

Recent clinical studies

Etiology

Koyama Y, Asahina M, Honma K, Arai K, Hattori T
Cerebellum 2009 Jun;8(2):130-6. doi: 10.1007/s12311-008-0076-2. PMID: 19009326
Katsanos KH, Nastos D, Noussias V, Christodoulou D, Kappas A, Tsianos EV
Dis Esophagus 2001;14(1):63-6. doi: 10.1111/j.1442-2050.2001.00152.x. PMID: 11422310

Diagnosis

Koyama Y, Asahina M, Honma K, Arai K, Hattori T
Cerebellum 2009 Jun;8(2):130-6. doi: 10.1007/s12311-008-0076-2. PMID: 19009326
Katsanos KH, Nastos D, Noussias V, Christodoulou D, Kappas A, Tsianos EV
Dis Esophagus 2001;14(1):63-6. doi: 10.1111/j.1442-2050.2001.00152.x. PMID: 11422310
Seigel RS, Seeger JF, Gabrielsen TO, Allen RJ
Radiology 1979 Jan;130(1):159-64. doi: 10.1148/130.1.159. PMID: 758643

Prognosis

Katsanos KH, Nastos D, Noussias V, Christodoulou D, Kappas A, Tsianos EV
Dis Esophagus 2001;14(1):63-6. doi: 10.1111/j.1442-2050.2001.00152.x. PMID: 11422310

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