U.S. flag

An official website of the United States government

Format

Send to:

Choose Destination

Neuronopathy, distal hereditary motor, autosomal recessive 9(HMNR9)

MedGen UID:
1850177
Concept ID:
C5882672
Disease or Syndrome
Synonyms: HMNR9; NEUROPATHY, DISTAL HEREDITARY MOTOR, AUTOSOMAL RECESSIVE 9
 
Gene (location): COQ7 (16p12.3)
 
Monarch Initiative: MONDO:0957874
OMIM®: 620402

Definition

Autosomal recessive distal hereditary motor neuronopathy-9 (HMNR9) is a slowly progressive peripheral neuropathy characterized by juvenile onset of distal muscle weakness and atrophy, resulting in gait difficulties. Most affected individuals also have upper limb involvement with weakness and atrophy of the hand muscles. Foot deformities are often present. Some patients may have mild sensory abnormalities or pyramidal signs. Electrophysiologic studies are consistent with a length-dependent axonal motor neuropathy (summary by Jacquier et al., 2023). For a discussion of genetic heterogeneity of autosomal recessive HMN, see HMNR1 (604320). [from OMIM]

Clinical features

From HPO
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).
Distal lower limb muscle weakness
MedGen UID:
324514
Concept ID:
C1836450
Finding
Reduced strength of the distal musculature of the legs.
Distal upper limb muscle weakness
MedGen UID:
461970
Concept ID:
C3150620
Finding
Reduced strength of the distal musculature of the arms.
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.
Disturbed sensory perception
MedGen UID:
508504
Concept ID:
C0150075
Finding
Alteration or impairment in the processing or interpretation of sensory information can lead to abnormal perceptions or experiences.
Hyperreflexia
MedGen UID:
57738
Concept ID:
C0151889
Finding
Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.
Hoffmann sign
MedGen UID:
78828
Concept ID:
C0277839
Sign or Symptom
A Hoffmann test is performed by flicking the fingernail of the long finger, from dorsal to volar, on each hand while the hand was supported by the examiner's hand. The test was done with the neck in the neutral position and then with the neck maximally forward flexed. Any flexion of the ipsilateral thumb and/or index finger was interpreted as a positive test.
Dementia
MedGen UID:
99229
Concept ID:
C0497327
Mental or Behavioral Dysfunction
A loss of global cognitive ability of sufficient amount to interfere with normal social or occupational function. Dementia represents a loss of previously present cognitive abilities, generally in adults, and can affect memory, thinking, language, judgment, and behavior.
Gait disturbance
MedGen UID:
107895
Concept ID:
C0575081
Finding
The term gait disturbance can refer to any disruption of the ability to walk.
Gowers sign
MedGen UID:
65865
Concept ID:
C0234182
Finding
A phenomenon whereby patients are not able to stand up without the use of the hands owing to weakness of the proximal muscles of the lower limbs.
Increased variability in muscle fiber diameter
MedGen UID:
336019
Concept ID:
C1843700
Finding
An abnormally high degree of muscle fiber size variation. This phenotypic feature can be observed upon muscle biopsy.
Proximal muscle weakness in lower limbs
MedGen UID:
356423
Concept ID:
C1866010
Finding
A lack of strength of the proximal muscles of the legs.
Proximal muscle weakness in upper limbs
MedGen UID:
356424
Concept ID:
C1866012
Finding
A lack of strength of the proximal muscles of the arms.
Lower limb amyotrophy
MedGen UID:
870475
Concept ID:
C4024921
Finding
Muscular atrophy affecting the lower limb.

Recent clinical studies

Etiology

Christodoulou K, Zamba E, Tsingis M, Mubaidin A, Horani K, Abu-Sheik S, El-Khateeb M, Kyriacou K, Kyriakides T, Al-Qudah AK, Middleton L
Ann Neurol 2000 Dec;48(6):877-84. PMID: 11117544

Clinical prediction guides

Christodoulou K, Zamba E, Tsingis M, Mubaidin A, Horani K, Abu-Sheik S, El-Khateeb M, Kyriacou K, Kyriakides T, Al-Qudah AK, Middleton L
Ann Neurol 2000 Dec;48(6):877-84. PMID: 11117544

Supplemental Content

Table of contents

    Clinical resources

    Consumer resources

    Recent activity

    Your browsing activity is empty.

    Activity recording is turned off.

    Turn recording back on

    See more...