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Charcot-Marie-Tooth disease axonal type 2N(CMT2N)

MedGen UID:: 413754
•Concept ID:: C2750090
•: Disease or Syndrome

Synonyms:	CHARCOT-MARIE-TOOTH DISEASE, AXONAL, AUTOSOMAL DOMINANT, TYPE 2N; Charcot-Marie-Tooth disease, type 2N; Charcot-Marie-Tooth Neuropathy Type 2N; CHARCOT-MARIE-TOOTH NEUROPATHY, AXONAL, TYPE 2N; CMT2N
SNOMED CT:	Autosomal dominant Charcot-Marie-Tooth disease type 2N (719515001)
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. Autosomal dominant inheritance (Orphanet)

Gene (location): Gene(s) directly associated with this condition or phenotype.	AARS1 (16q22.1)

Monarch Initiative:	MONDO:0013212
OMIM®:	613287
Orphanet:	ORPHA228174

Definition

A mild form of axonal Charcot-Marie-Tooth disease, a peripheral sensorimotor neuropathy, with characteristics of distal legs sensory loss and weakness that can be asymmetric. Tendon reflexes are reduced in the knees and absent in ankles. Progression is slow. [from SNOMEDCT_US]

Clinical features

From HPO

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.

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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).

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Hammertoe

MedGen UID:: 209712
•Concept ID:: C1136179
•: Anatomical Abnormality

Hyperextension of the metatarsal-phalangeal joint with hyperflexion of the proximal interphalangeal (PIP) joint.

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Lower limb muscle weakness

MedGen UID:: 324478
•Concept ID:: C1836296
•: Finding

Weakness of the muscles of the legs.

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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.

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Sensorineural hearing loss disorder

MedGen UID:: 9164
•Concept ID:: C0018784
•: Disease or Syndrome

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

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Areflexia

MedGen UID:: 115943
•Concept ID:: C0234146
•: Finding

Absence of neurologic reflexes such as the knee-jerk reaction.

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Hyporeflexia

MedGen UID:: 195967
•Concept ID:: C0700078
•: Finding

Reduction of neurologic reflexes such as the knee-jerk reaction.

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Peripheral axonal neuropathy

MedGen UID:: 266071
•Concept ID:: C1263857
•: Disease or Syndrome

An abnormality characterized by disruption of the normal functioning of peripheral axons.

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Distal sensory impairment

MedGen UID:: 335722
•Concept ID:: C1847584
•: Finding

An abnormal reduction in sensation in the distal portions of the extremities.

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Decreased motor nerve conduction velocity

MedGen UID:: 388130
•Concept ID:: C1858729
•: Finding

A type of decreased nerve conduction velocity that affects the motor neuron.

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Distal muscle weakness

MedGen UID:: 140883
•Concept ID:: C0427065
•: Finding

Reduced strength of the musculature of the distal extremities.

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Muscular atrophy

MedGen UID:: 892680
•Concept ID:: C0541794
•: Pathologic Function

The presence of skeletal muscular atrophy (which is also known as amyotrophy).

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Distal lower limb amyotrophy

MedGen UID:: 324515
•Concept ID:: C1836451
•: Disease or Syndrome

Muscular atrophy of distal leg muscles.

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Abnormality of limbs
Abnormality of the musculoskeletal system
Abnormality of the nervous system
Ear malformation
- Sensorineural hearing loss disorder

Term Hierarchy

GTR
MeSH
Orphanet

CClinical test, RResearch test, OOMIM, GGeneReviews, VClinVar

CROGVCharcot-Marie-Tooth disease

Fetal anomaly
- Congenital Systemic Disorder
  - Abnormality of the nervous system
    - Hereditary motor and sensory neuropathy
      - Charcot-Marie-Tooth disease
        Charcot-Marie-Tooth disease type 2
        Charcot-Marie-Tooth disease axonal type 2N

Follow this link to review classifications for Charcot-Marie-Tooth disease axonal type 2N in Orphanet.

Recent clinical studies

Diagnosis

NCAM1 and GDF15 are biomarkers of Charcot-Marie-Tooth disease in patients and mice.

Jennings MJ, Kagiava A, Vendredy L, Spaulding EL, Stavrou M, Hathazi D, Grüneboom A, De Winter V, Gess B, Schara U, Pogoryelova O, Lochmüller H, Borchers CH, Roos A, Burgess RW, Timmerman V, Kleopa KA, Horvath R
Brain 2022 Nov 21;145(11):3999-4015. doi: 10.1093/brain/awac055. PMID: 35148379 Free PMC Article

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