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Charcot-Marie-Tooth disease axonal type 2Z(CMT2Z)

MedGen UID:
1800448
Concept ID:
C5569025
Disease or Syndrome
Synonyms: CHARCOT-MARIE-TOOTH DISEASE, AXONAL, AUTOSOMAL DOMINANT, TYPE 2Z; CHARCOT-MARIE-TOOTH NEUROPATHY, TYPE 2Z
SNOMED CT: Autosomal dominant Charcot-Marie-Tooth disease type 2 due to MORC2 mutation (1187564009); Autosomal dominant Charcot-Marie-Tooth disease type 2Z (1187564009); Autosomal dominant Charcot-Marie-Tooth disease type 2 due to MORC2 (MORC family CW-type zinc finger 2) mutation (1187564009)
Modes of inheritance:
Autosomal dominant inheritance
MedGen UID:
141047
Concept ID:
C0443147
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 heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.
 
Gene (location): MORC2 (22q12.2)
 
Monarch Initiative: MONDO:0014736
OMIM®: 616688
Orphanet: ORPHA466768

Definition

Charcot-Marie-Tooth disease type 2Z (CMT2Z) is an autosomal dominant axonal peripheral neuropathy characterized by onset, usually in the first decade, of distal lower limb muscle weakness and sensory impairment. The disorder is progressive, and affected individuals tend to develop upper limb and proximal muscle involvement in an asymmetric pattern, resulting in severe disability late in adulthood. Rare occurrence of global developmental delay with impaired intellectual development or learning difficulties has been observed. In some instances, the same mutation may result in different phenotypic manifestations (CMT2Z or DIGFAN), which highlights the clinical spectrum associated with MORC2 mutations and may render the classification of patients into one or the other disorder challenging (summary by Sevilla et al., 2016, Ando et al., 2017, Guillen Sacoto et al., 2020). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210). [from OMIM]

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.
Wrist drop
MedGen UID:
533950
Concept ID:
C0231666
Finding
A condition in which the affected individual cannot extend the wrist, which hangs flaccidly.
Absent Achilles reflex
MedGen UID:
108240
Concept ID:
C0558845
Finding
Absence of the Achilles reflex (also known as the ankle jerk reflex), which can normally be elicited by tapping the tendon is tapped while the foot is dorsiflexed.
Pes cavus
MedGen UID:
675590
Concept ID:
C0728829
Congenital Abnormality
An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight).
Foot dorsiflexor weakness
MedGen UID:
356163
Concept ID:
C1866141
Finding
Weakness of the muscles responsible for dorsiflexion of the foot, that is, of the movement of the toes towards the shin. The foot dorsiflexors include the tibialis anterior, the extensor hallucis longus, the extensor digitorum longus, and the peroneus tertius muscles.
Split hand
MedGen UID:
397570
Concept ID:
C2699510
Congenital Abnormality
A condition in which middle parts of the hand (fingers and metacarpals) are missing giving a cleft appearance. The severity is very variable ranging from slightly hypoplastic middle fingers over absent middel fingers as far as oligo- or monodactyl hands.
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
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).
Fasciculations
MedGen UID:
5124
Concept ID:
C0015644
Sign or Symptom
Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units.
Babinski sign
MedGen UID:
19708
Concept ID:
C0034935
Finding
Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract.
Clumsiness
MedGen UID:
66690
Concept ID:
C0233844
Sign or Symptom
Lack of physical coordination resulting in an abnormal tendency to drop items or bump into objects.
Abnormal pyramidal sign
MedGen UID:
68582
Concept ID:
C0234132
Sign or Symptom
Functional neurological abnormalities related to dysfunction of the pyramidal tract.
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
High pitched voice
MedGen UID:
66836
Concept ID:
C0241703
Finding
An abnormal increase in the pitch (frequency) of the voice.
Incoordination
MedGen UID:
141714
Concept ID:
C0520966
Finding
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.
Myokymia
MedGen UID:
146882
Concept ID:
C0684219
Sign or Symptom
Myokymia consists of involuntary, fine, continuous, undulating contractions that spread across the affected striated muscle.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Gait ataxia
MedGen UID:
155642
Concept ID:
C0751837
Sign or Symptom
A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall.
Distal sensory impairment
MedGen UID:
335722
Concept ID:
C1847584
Finding
An abnormal reduction in sensation in the distal portions of the extremities.
Impaired distal vibration sensation
MedGen UID:
381262
Concept ID:
C1853767
Finding
A decrease in the ability to perceive vibration in the distal portions of the limbs.
Motor delay
MedGen UID:
381392
Concept ID:
C1854301
Finding
A type of Developmental delay characterized by a delay in acquiring motor skills.
Decreased motor nerve conduction velocity
MedGen UID:
388130
Concept ID:
C1858729
Finding
A type of decreased nerve conduction velocity that affects the motor neuron.
Impaired distal tactile sensation
MedGen UID:
867225
Concept ID:
C4021583
Finding
A reduced sense of touch (tactile sensation) on the skin of the distal limbs. This is usually tested with a wisp of cotton or a fine camel's hair brush, by asking patients to say 'now' each time they feel the stimulus.
Impaired distal proprioception
MedGen UID:
867227
Concept ID:
C4021585
Finding
A loss or impairment of the sensation of the relative position of parts of the body and joint position occuring at distal joints.
Decreased amplitude of sensory action potentials
MedGen UID:
870496
Concept ID:
C4024943
Finding
A reduction in the amplitude of sensory nerve action potential. This feature is measured by nerve conduction studies.
Hypertonia
MedGen UID:
10132
Concept ID:
C0026826
Finding
A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move.
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.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Muscle spasm
MedGen UID:
52431
Concept ID:
C0037763
Sign or Symptom
Sudden and involuntary contractions of one or more muscles.
Proximal muscle weakness
MedGen UID:
113169
Concept ID:
C0221629
Finding
A lack of strength of the proximal muscles.
Difficulty walking
MedGen UID:
86319
Concept ID:
C0311394
Finding
Reduced ability to walk (ambulate).
Distal muscle weakness
MedGen UID:
140883
Concept ID:
C0427065
Finding
Reduced strength of the musculature of the distal extremities.
Distal amyotrophy
MedGen UID:
338530
Concept ID:
C1848736
Disease or Syndrome
Muscular atrophy affecting muscles in the distal portions of the extremities.
Intrinsic hand muscle atrophy
MedGen UID:
351202
Concept ID:
C1864716
Finding
Atrophy of the intrinsic muscle groups of the hand, comprising the thenar and hypothenar muscles; the interossei muscles; and the lumbrical muscles.

Recent clinical studies

Diagnosis

Stafki SA, Turner J, Littel HR, Bruels CC, Truong D, Knirsch U, Stettner GM, Graf U, Berger W, Kinali M, Jungbluth H, Pacak CA, Hughes J, Mirchi A, Derksen A, Vincent-Delorme C, Theil AF, Bernard G, Ellis D, Fassihi H, Lehmann AR, Laugel V, Mohammed S, Kang PB
Pediatr Neurol 2023 Apr;141:79-86. Epub 2023 Jan 24 doi: 10.1016/j.pediatrneurol.2023.01.011. PMID: 36791574Free PMC Article
Ando M, Okamoto Y, Yoshimura A, Yuan JH, Hiramatsu Y, Higuchi Y, Hashiguchi A, Mitsui J, Ishiura H, Fukumura S, Matsushima M, Ochi N, Tsugawa J, Morishita S, Tsuji S, Takashima H
Eur J Neurol 2017 Oct;24(10):1274-1282. Epub 2017 Aug 3 doi: 10.1111/ene.13360. PMID: 28771897

Clinical prediction guides

Ando M, Okamoto Y, Yoshimura A, Yuan JH, Hiramatsu Y, Higuchi Y, Hashiguchi A, Mitsui J, Ishiura H, Fukumura S, Matsushima M, Ochi N, Tsugawa J, Morishita S, Tsuji S, Takashima H
Eur J Neurol 2017 Oct;24(10):1274-1282. Epub 2017 Aug 3 doi: 10.1111/ene.13360. PMID: 28771897

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