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Neuronopathy, distal hereditary motor, autosomal recessive 8(SORDD; HMNR8)

MedGen UID:
1714781
Concept ID:
C5394466
Disease or Syndrome
Synonyms: NEUROPATHY, DISTAL HEREDITARY MOTOR, AUTOSOMAL RECESSIVE 8; SORBITOL DEHYDROGENASE DEFICIENCY; Sorbitol dehydrogenase deficiency with peripheral neuropathy
 
Gene (location): SORD (15q21.1)
 
Monarch Initiative: MONDO:0030055
OMIM®: 618912

Definition

Autosomal recessive distal hereditary motor neuronopathy-8 (HMNR8), or sorbitol dehydrogenase deficiency with peripheral neuropathy (SORDD), is characterized by onset of distal muscle weakness mainly affecting the lower limbs and resulting in difficulty walking. Onset of symptoms is usually in the first or second decades of life, although later adult onset has been reported; the disorder is slowly progressive. Nerve conduction velocities are most consistent with an axonal process. More variable features include distal sensory impairment, upper limb tremor, and scoliosis. Laboratory studies show increased serum sorbitol (summary by Cortese et al., 2020). For a general phenotypic description and 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.
Gait disturbance
MedGen UID:
107895
Concept ID:
C0575081
Finding
The term gait disturbance can refer to any disruption of the ability to walk.
Impaired vibratory sensation
MedGen UID:
220959
Concept ID:
C1295585
Finding
A decrease in the ability to perceive vibration. Clinically, this is usually tested with a tuning fork which vibrates at 128 Hz and is applied to bony prominences such as the malleoli at the ankles or the metacarpal-phalangeal joints. There is a slow decay of vibration from the tuning fork. The degree of vibratory sense loss can be crudely estimated by counting the number of seconds that the examiner can perceive the vibration longer than the patient.
Impaired pain sensation
MedGen UID:
373348
Concept ID:
C1837522
Finding
Reduced ability to perceive painful stimuli.
Decreased motor nerve conduction velocity
MedGen UID:
388130
Concept ID:
C1858729
Finding
A type of decreased nerve conduction velocity that affects the motor neuron.
Decreased amplitude of sensory action potentials
MedGen UID:
870496
Concept ID:
C4024943
Finding
A reduction in the amplitude of sensory nerve action potential. This feature is measured by nerve conduction studies.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Proximal muscle weakness in lower limbs
MedGen UID:
356423
Concept ID:
C1866010
Finding
A lack of strength of the proximal muscles of the legs.
Increased serum sorbitol concentration
MedGen UID:
1751042
Concept ID:
C5421627
Finding
An increased level of sorbitol in the blood circulation.

Recent clinical studies

Etiology

Irobi J, Dierick I, Jordanova A, Claeys KG, De Jonghe P, Timmerman V
Neuromolecular Med 2006;8(1-2):131-46. doi: 10.1385/nmm:8:1-2:131. PMID: 16775372

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