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Neuronopathy, distal hereditary motor, autosomal recessive 7(HMNMYO; HMNR7)

MedGen UID:
1786836
Concept ID:
C5543119
Disease or Syndrome
Synonyms: NEUROPATHY, DISTAL HEREDITARY MOTOR, AUTOSOMAL RECESSIVE 7; Neuropathy, hereditary motor, with myopathic features
 
Gene (location): VWA1 (1p36.33)
 
Monarch Initiative: MONDO:0030977
OMIM®: 619216

Definition

Autosomal recessive distal hereditary motor neuronopathy-7 (HMNR7) is characterized by onset of lower leg weakness in the first decade. Affected individuals have difficulty climbing stairs and problems standing on the heels. Some patients have later onset well into the adult years. Most patients have foot deformities, and some may have leg muscle atrophy. The disorder is slowly progressive and often involves the upper limbs. Muscle biopsy and electrophysiologic studies are consistent with both a myopathic process and an axonal motor neuropathy. Sensory abnormalities are not typically present, and patients remain ambulatory. The phenotype shows phenotypic overlap with distal hereditary motor neuropathy, but can distinguished by the presence of myopathic features (summary by Deschauer et al., 2021 and Pagnamenta et al., 2021). For a discussion of genetic heterogeneity of autosomal recessive HMN, see HMNR1 (604320). [from OMIM]

Clinical features

From HPO
Myalgia
MedGen UID:
68541
Concept ID:
C0231528
Sign or Symptom
Pain in muscle.
Clubfoot
MedGen UID:
3130
Concept ID:
C0009081
Congenital Abnormality
Clubfoot is a congenital limb deformity defined as fixation of the foot in cavus, adductus, varus, and equinus (i.e., inclined inwards, axially rotated outwards, and pointing downwards) with concomitant soft tissue abnormalities (Cardy et al., 2007). Clubfoot may occur in isolation or as part of a syndrome (e.g., diastrophic dysplasia, 222600). Clubfoot has been reported with deficiency of long bones and mirror-image polydactyly (Gurnett et al., 2008; Klopocki et al., 2012).
Scapular winging
MedGen UID:
66822
Concept ID:
C0240953
Anatomical Abnormality
Abnormal protrusion of the scapula away from the surface of the back.
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.
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.
Distal upper limb muscle weakness
MedGen UID:
461970
Concept ID:
C3150620
Finding
Reduced strength of the distal musculature of the arms.
Paresthesia
MedGen UID:
14619
Concept ID:
C0030554
Disease or Syndrome
Abnormal sensations such as tingling, pricking, or numbness of the skin with no apparent physical cause.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Motor axonal neuropathy
MedGen UID:
413108
Concept ID:
C2749625
Disease or Syndrome
Progressive impairment of function of motor axons with muscle weakness, atrophy, and cramps. The deficits are length-dependent, meaning that muscles innervated by the longest nerves are affected first, so that for instance the arms are affected at a later age than the onset of deficits involving the lower leg.
Impaired tactile sensation
MedGen UID:
866866
Concept ID:
C4021221
Finding
A reduced sense of touch (tactile sensation). This is usually tested with a wisp of cotton or a fine camel's hair brush, by asking patients to say 'now' each time they feel the stimulus.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Flexion contracture
MedGen UID:
83069
Concept ID:
C0333068
Anatomical Abnormality
A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.
Frequent falls
MedGen UID:
163408
Concept ID:
C0850703
Finding
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.
EMG: myopathic abnormalities
MedGen UID:
867362
Concept ID:
C4021726
Pathologic Function
The presence of abnormal electromyographic patterns indicative of myopathy, such as small-short polyphasic motor unit potentials.
Lower limb amyotrophy
MedGen UID:
870475
Concept ID:
C4024921
Finding
Muscular atrophy affecting the lower limb.
Tongue fasciculations
MedGen UID:
65987
Concept ID:
C0239548
Finding
Fasciculations or fibrillation affecting the tongue muscle.

Recent clinical studies

Etiology

Ververis A, Dajani R, Koutsou P, Aloqaily A, Nelson-Williams C, Loring E, Arafat A, Mubaidin AF, Horany K, Bader MB, Al-Baho Y, Ali B, Muhtaseb A, DeSpenza T Jr, Al-Qudah AA, Middleton LT, Zamba-Papanicolaou E, Lifton R, Christodoulou K
J Med Genet 2020 Mar;57(3):178-186. Epub 2019 Sep 11 doi: 10.1136/jmedgenet-2019-106108. PMID: 31511340Free PMC Article
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

Diagnosis

Ververis A, Dajani R, Koutsou P, Aloqaily A, Nelson-Williams C, Loring E, Arafat A, Mubaidin AF, Horany K, Bader MB, Al-Baho Y, Ali B, Muhtaseb A, DeSpenza T Jr, Al-Qudah AA, Middleton LT, Zamba-Papanicolaou E, Lifton R, Christodoulou K
J Med Genet 2020 Mar;57(3):178-186. Epub 2019 Sep 11 doi: 10.1136/jmedgenet-2019-106108. PMID: 31511340Free PMC Article

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

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