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Charcot-Marie-Tooth disease, type IA(CMT1A)

MedGen UID:
75727
Concept ID:
C0270911
Disease or Syndrome
Synonyms: Charcot-Marie-Tooth disease type 1A; CHARCOT-MARIE-TOOTH DISEASE, AUTOSOMAL DOMINANT, WITH FOCALLY FOLDED MYELIN SHEATHS, TYPE 1A; Charcot-Marie-Tooth disease, demyelinating, type 1A; CHARCOT-MARIE-TOOTH NEUROPATHY, TYPE 1A; CMT 1A; CMT1A; Hereditary motor and sensory neuropathy 1A; HEREDITARY MOTOR AND SENSORY NEUROPATHY IA; HMSN 1A
SNOMED CT: Charcot-Marie-Tooth disease, type IA (40632002)
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): PMP22 (17p12)
 
Monarch Initiative: MONDO:0007309
OMIM®: 118220
Orphanet: ORPHA101081

Definition

For a general phenotypic description and a discussion of genetic heterogeneity of Charcot-Marie-Tooth disease type 1, see CMT1B (118200). CMT1A is the most common form of CMT. The average age of onset of clinical symptoms is 12.2 +/- 7.3 years. Slow nerve conduction velocity (NCV) less than 38 m/s is highly diagnostic and is a 100% penetrant phenotype independent of age (Lupski et al., 1991, 1992). [from OMIM]

Clinical features

From HPO
Limb muscle weakness
MedGen UID:
107956
Concept ID:
C0587246
Finding
Reduced strength and weakness of the muscles of the arms and legs.
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).
Hammertoe
MedGen UID:
209712
Concept ID:
C1136179
Anatomical Abnormality
Hyperextension of the metatarsal-phalangeal joint with hyperflexion of the proximal interphalangeal (PIP) joint.
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 middle fingers as far as oligo- or monodactyl hands.
Ulnar claw
MedGen UID:
871311
Concept ID:
C4025799
Congenital Abnormality
An abnormal hand position characterized by hyperextension of the fourth and fifth fingers at the metacarpophalangeal joints and flexion of the interphalangeal joints of the same fingers such that they are curled towards the palm.
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
Peripheral neuropathy
MedGen UID:
18386
Concept ID:
C0031117
Disease or Syndrome
Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course.
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
Steppage gait
MedGen UID:
98105
Concept ID:
C0427149
Finding
An abnormal gait pattern that arises from weakness of the pretibial and peroneal muscles due to a lower motor neuron lesion. Affected patients have footdrop and are unable to dorsiflex and evert the foot. The leg is lifted high on walking so that the toes clear the ground, and there may be a slapping noise when the foot strikes the ground again.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Hypertrophic nerve changes
MedGen UID:
322038
Concept ID:
C1832776
Finding
Segmental peripheral demyelination/remyelination
MedGen UID:
335873
Concept ID:
C1843077
Finding
A segmental pattern of demyelination and regeneration (remyelination) affecting peripheral nerves.
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 number of peripheral myelinated nerve fibers
MedGen UID:
346872
Concept ID:
C1858285
Finding
A loss of myelinated nerve fibers in the peripheral nervous system (in general, this finding can be observed on nerve biopsy).
Decreased motor nerve conduction velocity
MedGen UID:
388130
Concept ID:
C1858729
Finding
A type of decreased nerve conduction velocity that affects the motor neuron.
Distal muscle weakness
MedGen UID:
140883
Concept ID:
C0427065
Finding
Reduced strength of the musculature of the distal extremities.
Kyphoscoliosis
MedGen UID:
154361
Concept ID:
C0575158
Anatomical Abnormality
An abnormal curvature of the spine in both a coronal (lateral) and sagittal (back-to-front) plane.
Distal amyotrophy
MedGen UID:
338530
Concept ID:
C1848736
Disease or Syndrome
Muscular atrophy affecting muscles in the distal portions of the extremities.
Cold-induced muscle cramps
MedGen UID:
396193
Concept ID:
C1861675
Finding
Sudden and involuntary contractions of one or more muscles brought on by exposure to cold temperatures.

Term Hierarchy

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

Professional guidelines

PubMed

Bai Y, Treins C, Volpi VG, Scapin C, Ferri C, Mastrangelo R, Touvier T, Florio F, Bianchi F, Del Carro U, Baas FF, Wang D, Miniou P, Guedat P, Shy ME, D'Antonio M
Mol Neurobiol 2022 Jul;59(7):4159-4178. Epub 2022 Apr 30 doi: 10.1007/s12035-022-02838-y. PMID: 35501630Free PMC Article
Sanmaneechai O, Feely S, Scherer SS, Herrmann DN, Burns J, Muntoni F, Li J, Siskind CE, Day JW, Laura M, Sumner CJ, Lloyd TE, Ramchandren S, Shy RR, Grider T, Bacon C, Finkel RS, Yum SW, Moroni I, Piscosquito G, Pareyson D, Reilly MM, Shy ME; Inherited Neuropathies Consortium - Rare Disease Clinical Research Consortium (INC-RDCRC)
Brain 2015 Nov;138(Pt 11):3180-92. Epub 2015 Aug 25 doi: 10.1093/brain/awv241. PMID: 26310628Free PMC Article
de Visser M
Neuromuscul Disord 1993 Jan;3(1):77-9. doi: 10.1016/0960-8966(93)90045-l. PMID: 8329892

Curated

Aretz S, Rautenstrauss B, Timmerman V
Eur J Hum Genet 2010 Sep;18(9) Epub 2010 May 26 doi: 10.1038/ejhg.2010.75. PMID: 20512157Free PMC Article

Recent clinical studies

Clinical prediction guides

Müller E, Mostacciuolo ML, Micaglio G, Angelini C, Danieli GA
Hum Genet 1992 Nov;90(3):231-4. doi: 10.1007/BF00220067. PMID: 1487234
Patel PI, Garcia C, Montes de Oca-Luna R, Malamut RI, Franco B, Slaugenhaupt S, Chakravarti A, Lupski JR
Am J Hum Genet 1990 Dec;47(6):926-34. PMID: 1978559Free PMC Article

Supplemental Content

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    Clinical resources

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    • PubMed
      See practice and clinical guidelines in PubMed. The search results may include broader topics and may not capture all published guidelines. See the FAQ for details.
    • Bookshelf
      See practice and clinical guidelines in NCBI Bookshelf. The search results may include broader topics and may not capture all published guidelines. See the FAQ for details.

    Curated

    • EuroGenetest, 2010
      Clinical utility gene card for: HMSN/HNPP HMSN types 1, 2, 3, 6 (CMT1,2,4, DSN, CHN, GAN, CCFDN, HNA); HNPP

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