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Charcot-Marie-Tooth disease type 4B3(CMT4B3)

MedGen UID:
811329
Concept ID:
C3695063
Disease or Syndrome
Synonyms: Charcot-Marie-Tooth Neuropathy Type 4B3; Charcot-Marie-Tooth Neuropathy Type 4B3 (CMT4B3)
SNOMED CT: Charcot-Marie-Tooth disease type 4B3 (763345008); Charcot-Marie-Tooth disease with focally folded myelin (763345008)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): SBF1 (22q13.33)
 
Monarch Initiative: MONDO:0014117
OMIM®: 615284
Orphanet: ORPHA363981

Definition

A subtype of Charcot-Marie-Tooth type 4 with characteristics of childhood onset of slowly progressing, demyelinating sensorimotor neuropathy, focally folded myelin sheaths in nerve biopsy, reduced nerve conduction velocities and the typical Charcot-Marie-Tooth phenotype (i.e. distal muscle weakness and atrophy, and sensory loss). There is evidence this disease is caused by homozygous or compound heterozygous mutation in the SBF1 gene on chromosome 22q. [from SNOMEDCT_US]

Clinical features

From HPO
Urinary incontinence
MedGen UID:
22579
Concept ID:
C0042024
Finding
Loss of the ability to control the urinary bladder leading to involuntary urination.
Pes planus
MedGen UID:
42034
Concept ID:
C0016202
Anatomical Abnormality
A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced.
Syndactyly
MedGen UID:
52619
Concept ID:
C0039075
Congenital Abnormality
Webbing or fusion of the fingers or toes, involving soft parts only or including bone structure. Bony fusions are referred to as "bony" syndactyly if the fusion occurs in a radio-ulnar axis. Fusions of bones of the fingers or toes in a proximo-distal axis are referred to as "symphalangism".
Upper limb muscle weakness
MedGen UID:
305607
Concept ID:
C1698196
Finding
Weakness of the muscles of the arms.
Lower limb muscle weakness
MedGen UID:
324478
Concept ID:
C1836296
Finding
Weakness of the muscles of the legs.
Distal lower limb muscle weakness
MedGen UID:
324514
Concept ID:
C1836450
Finding
Reduced strength of the distal musculature of the legs.
Muscle fibrillation
MedGen UID:
65418
Concept ID:
C0231531
Finding
Fine, rapid twitching of individual muscle fibers with little or no movement of the muscle as a whole. If a motor neuron or its axon is destroyed, the muscle fibers it innervates undergo denervation atrophy. This leads to hypersensitivity of individual muscle fibers to acetyl choline so that they may contract spontaneously. Isolated activity of individual muscle fibers is generally so fine it cannot be seen through the intact skin, although it can be recorded as a short-duration spike in the EMG.
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
Gait disturbance
MedGen UID:
107895
Concept ID:
C0575081
Finding
The term gait disturbance can refer to any disruption of the ability to walk. In general, this can refer to neurological diseases but also fractures or other sources of pain that is triggered upon walking. However, in the current context gait disturbance refers to difficulty walking on the basis of a neurological or muscular disease.
Loss of ambulation
MedGen UID:
332305
Concept ID:
C1836843
Finding
Inability to walk in a person who previous had the ability to walk.
Myelin outfoldings
MedGen UID:
334341
Concept ID:
C1843168
Finding
The presence of excessive redundant myelin in the peripheral nerve sheath.
Distal sensory impairment
MedGen UID:
335722
Concept ID:
C1847584
Finding
An abnormal reduction in sensation in the distal portions of the extremities.
Onion bulb formation
MedGen UID:
376237
Concept ID:
C1847906
Finding
Repeated episodes of segmental demyelination and remyelination lead to the accumulation of supernumerary Schwann cells around axons, which is referred to as onion bulb formation. This finding affects peripheral nerves.
Decreased nerve conduction velocity
MedGen UID:
347509
Concept ID:
C1857640
Finding
A reduction in the speed at which electrical signals propagate along the axon of a neuron.
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.
Brain atrophy
MedGen UID:
1643639
Concept ID:
C4551584
Disease or Syndrome
Partial or complete wasting (loss) of brain tissue that was once present.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Skeletal muscle atrophy
MedGen UID:
892680
Concept ID:
C0541794
Pathologic Function
The presence of skeletal muscular atrophy (which is also known as amyotrophy).
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Ophthalmoplegia
MedGen UID:
45205
Concept ID:
C0029089
Sign or Symptom
Paralysis of one or more extraocular muscles that are responsible for eye movements.
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.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVCharcot-Marie-Tooth disease type 4B3
Follow this link to review classifications for Charcot-Marie-Tooth disease type 4B3 in Orphanet.

Recent clinical studies

Diagnosis

Flusser H, Halperin D, Kadir R, Shorer Z, Shelef I, Birk OS
Clin Genet 2018 Nov;94(5):473-479. Epub 2018 Aug 9 doi: 10.1111/cge.13419. PMID: 30039846

Supplemental Content

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