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Hereditary motor and sensory neuropathy with optic atrophy(CMT6; HMSN6A; HMSN6; CMT6A)

MedGen UID:
140747
Concept ID:
C0393807
Disease or Syndrome
Synonyms: CHARCOT-MARIE-TOOTH DISEASE, TYPE 6; Hereditary Motor and Sensory Neuropathy VI; PERIPHERAL NEUROPATHY AND OPTIC ATROPHY
SNOMED CT: Hereditary motor and sensory neuropathy type VI (128203003); Hereditary motor-sensory neuropathy with optic atrophy (128203003); Hereditary sensory and motor neuropathy, type VI (128203003); Hereditary motor-sensory neuropathy, type VI (128203003); HMSN VI (128203003); Hereditary motor and sensory neuropathy with optic atrophy (128203003)
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).
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.
 
Related genes: SLC25A46, MFN2, PDXK
 
Monarch Initiative: MONDO:0019551
OMIM®: 601152; 608507
Orphanet: ORPHA90120

Disease characteristics

Excerpted from the GeneReview: MFN2 Hereditary Motor and Sensory Neuropathy
MFN2 hereditary motor and sensory neuropathy (MFN2-HMSN) is a classic axonal peripheral sensorimotor neuropathy, inherited in either an autosomal dominant (AD) manner (~90%) or an autosomal recessive (AR) manner (~10%). MFN2-HMSN is characterized by more severe involvement of the lower extremities than the upper extremities, distal upper-extremity involvement as the neuropathy progresses, more prominent motor deficits than sensory deficits, and normal (>42 m/s) or only slightly decreased nerve conduction velocities (NCVs). Postural tremor is common. Median onset is age 12 years in the AD form and age eight years in the AR form. The prevalence of optic atrophy is approximately 7% in the AD form and approximately 20% in the AR form. [from GeneReviews]
Authors:
Stephan Züchner   view full author information

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).
Tinnitus
MedGen UID:
52760
Concept ID:
C0040264
Disease or Syndrome
Tinnitus is an auditory perception that can be described as the experience of sound, in the ear or in the head, in the absence of external acoustic stimulation.
Mild neurosensory hearing impairment
MedGen UID:
867180
Concept ID:
C4021538
Disease or Syndrome
The presence of a mild form of sensorineural hearing impairment.
Anosmia
MedGen UID:
1950
Concept ID:
C0003126
Finding
An inability to perceive odors. This is a general term describing inability to smell arising in any part of the process of smelling from absorption of odorants into the nasal mucous overlying the olfactory epithelium, diffusion to the cilia, binding to olfactory receptor sites, generation of action potentials in olfactory neurons, and perception of a smell.
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
Positive Romberg sign
MedGen UID:
66017
Concept ID:
C0240914
Finding
The patient stands with the feet placed together and balance and is asked to close his or her eyes. A loss of balance upon eye closure is a positive Romberg sign and is interpreted as indicating a deficit in proprioception.
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.
Abnormality of visual evoked potentials
MedGen UID:
105509
Concept ID:
C0522214
Finding
An anomaly of visually evoked potentials (VEP), which are electrical potentials, initiated by brief visual stimuli, which are recorded from the scalp overlying the visual cortex.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Distal sensory impairment of all modalities
MedGen UID:
322937
Concept ID:
C1836527
Finding
Reduced ability to sense pain, temperature, touch, vibration stimuli in the distal regions of the extremities.
Distal sensory impairment
MedGen UID:
335722
Concept ID:
C1847584
Finding
An abnormal reduction in sensation in the distal portions of the extremities.
Decreased motor nerve conduction velocity
MedGen UID:
388130
Concept ID:
C1858729
Finding
A type of decreased nerve conduction velocity that affects the motor neuron.
Axonal degeneration/regeneration
MedGen UID:
368889
Concept ID:
C1968790
Finding
A pattern of simultaneous degeneration and regeneration of axons (see comment).
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Proximal muscle weakness
MedGen UID:
113169
Concept ID:
C0221629
Finding
A lack of strength of the proximal muscles.
Distal muscle weakness
MedGen UID:
140883
Concept ID:
C0427065
Finding
Reduced strength of the musculature of the distal extremities.
Lumbar hyperlordosis
MedGen UID:
263149
Concept ID:
C1184923
Finding
An abnormal accentuation of the inward curvature of the spine in the lumbar region.
Distal amyotrophy
MedGen UID:
338530
Concept ID:
C1848736
Disease or Syndrome
Muscular atrophy affecting muscles in the distal portions of the extremities.
Vocal cord paresis
MedGen UID:
155888
Concept ID:
C0751576
Disease or Syndrome
Decreased strength of the vocal folds.
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.
Central scotoma
MedGen UID:
57750
Concept ID:
C0152191
Finding
An area of depressed vision located at the point of fixation and that interferes with central vision.
Color vision defect
MedGen UID:
115964
Concept ID:
C0234629
Finding
An anomaly in the ability to discriminate between or recognize colors.
Optic disc pallor
MedGen UID:
108218
Concept ID:
C0554970
Finding
A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression.
Dysmetric saccades
MedGen UID:
322908
Concept ID:
C1836392
Finding
The controller signal for saccadic eye movements has two components
Slow decrease in visual acuity
MedGen UID:
343976
Concept ID:
C1853141
Finding

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
Follow this link to review classifications for Hereditary motor and sensory neuropathy with optic atrophy in Orphanet.

Professional guidelines

PubMed

Méreaux JL, Firanescu C, Coarelli G, Kvarnung M, Rodrigues R, Pegoraro E, Tazir M, Taithe F, Valter R, Huin V, Lidström K, Banneau G, Morais S, Parodi L, Coutelier M, Papin M, Svenningsson P, Azulay JP, Alonso I, Nilsson D, Brice A, Le Guern E, Press R, Vazza G, Loureiro JL, Goizet C, Durr A, Paucar M, Stevanin G
Neurogenetics 2021 Mar;22(1):71-79. Epub 2021 Jan 23 doi: 10.1007/s10048-020-00633-2. PMID: 33486633Free PMC Article
van Gassen KL, van der Heijden CD, de Bot ST, den Dunnen WF, van den Berg LH, Verschuuren-Bemelmans CC, Kremer HP, Veldink JH, Kamsteeg EJ, Scheffer H, van de Warrenburg BP
Brain 2012 Oct;135(Pt 10):2994-3004. Epub 2012 Sep 10 doi: 10.1093/brain/aws224. PMID: 22964162
Lott MT, Voljavec AS, Wallace DC
Am J Ophthalmol 1990 Jun 15;109(6):625-31. doi: 10.1016/s0002-9394(14)72429-8. PMID: 2346190

Recent clinical studies

Etiology

Sommer C, Schröder JM
Arch Neurol 1989 Sep;46(9):973-7. doi: 10.1001/archneur.1989.00520450043017. PMID: 2775013

Diagnosis

Braunisch MC, Gallwitz H, Abicht A, Diebold I, Holinski-Feder E, Van Maldergem L, Lammens M, Kovács-Nagy R, Alhaddad B, Strom TM, Meitinger T, Senderek J, Rudnik-Schöneborn S, Haack TB
Clin Genet 2018 Feb;93(2):255-265. Epub 2017 Nov 8 doi: 10.1111/cge.13084. PMID: 28653766
Chalmers RM, Riordan-Eva P, Wood NW
J Neurol Neurosurg Psychiatry 1997 Apr;62(4):385-7. doi: 10.1136/jnnp.62.4.385. PMID: 9120454Free PMC Article
Schröder JM
Brain Pathol 1993 Apr;3(2):177-90. doi: 10.1111/j.1750-3639.1993.tb00742.x. PMID: 8293179

Prognosis

Braunisch MC, Gallwitz H, Abicht A, Diebold I, Holinski-Feder E, Van Maldergem L, Lammens M, Kovács-Nagy R, Alhaddad B, Strom TM, Meitinger T, Senderek J, Rudnik-Schöneborn S, Haack TB
Clin Genet 2018 Feb;93(2):255-265. Epub 2017 Nov 8 doi: 10.1111/cge.13084. PMID: 28653766

Clinical prediction guides

Sommer C, Schröder JM
Arch Neurol 1989 Sep;46(9):973-7. doi: 10.1001/archneur.1989.00520450043017. PMID: 2775013

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