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Neuronopathy, distal hereditary motor, type 7A(HMN7A; HMND7)

MedGen UID:
322474
Concept ID:
C1834703
Disease or Syndrome
Synonyms: HARPER-YOUNG MYOPATHY; HMN VIIA; Neuronopathy, distal hereditary motor, autosomal dominant 7; NEURONOPATHY, DISTAL HEREDITARY MOTOR, HARDING TYPE VIIA; Neuronopathy, distal hereditary motor, type viia; NEUROPATHY, DISTAL HEREDITARY MOTOR, HARDING TYPE VIIA; SPINAL MUSCULAR ATROPHY, DISTAL, WITH VOCAL CORD PARALYSIS
 
Gene (location): SLC5A7 (2q12.3)
 
Monarch Initiative: MONDO:0008024
OMIM®: 158580

Definition

Autosomal dominant distal hereditary motor neuronopathy-7 (HMND7) is a neurologic disorder characterized by onset in the second decade of progressive distal muscle wasting and weakness affecting the upper and lower limbs and resulting in walking difficulties and hand grip. There is significant muscle atrophy of the hands and lower limbs. The disorder is associated with vocal cord paresis due to involvement of the tenth cranial nerve (summary by Barwick et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant distal HMN, see HMND1 (182960). [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).
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.
Tremor
MedGen UID:
21635
Concept ID:
C0040822
Sign or Symptom
An unintentional, oscillating to-and-fro muscle movement about a joint axis.
Gait disturbance
MedGen UID:
107895
Concept ID:
C0575081
Finding
The term gait disturbance can refer to any disruption of the ability to walk.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Abnormal motor nerve conduction velocity
MedGen UID:
866684
Concept ID:
C4021031
Anatomical Abnormality
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.
Increased jitter at single fiber EMG
MedGen UID:
866698
Concept ID:
C4021045
Finding
The variation in the time interval between the two action potentials of the same motor unit is called jitter. This term therefore applies to increased variability in the interval between successive action potentials of the same motor unit, which is measured by electromyography (EMG).
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation
MedGen UID:
892749
Concept ID:
C4021728
Finding
A compound muscle action potential (CMAP) is a type of electromyography (EMG). CMAP refers to a group of almost simultaneous action potentials from several muscle fibers in the same area evoked by stimulation of the supplying motor nerve and are recorded as one multipeaked summated action potential. This abnormality refers to a greater than normal decrease in the amplitude during the course of the investigation.
Vocal cord paralysis
MedGen UID:
53047
Concept ID:
C0042928
Disease or Syndrome
A loss of the ability to move the vocal folds.
Vocal cord paresis
MedGen UID:
155888
Concept ID:
C0751576
Disease or Syndrome
Decreased strength of the vocal folds.

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