Neuronopathy, distal hereditary motor, type 9(HMN9; DHMN9)

MedGen UID:: 1617571
•Concept ID:: C4540265
•: Disease or Syndrome

Synonyms:	NEURONOPATHY, DISTAL HEREDITARY MOTOR, AUTOSOMAL DOMINANT 9; NEURONOPATHY, DISTAL HEREDITARY MOTOR, TYPE IX; NEUROPATHY, DISTAL HEREDITARY MOTOR, TYPE IX

Gene (location): Gene(s) directly associated with this condition or phenotype.	WARS1 (14q32.2)

Monarch Initiative:	MONDO:0060585
OMIM®:	617721

Definition

HMND9 is an autosomal dominant neurologic disorder characterized by juvenile onset of slowly progressive distal muscle weakness and atrophy affecting both the lower and upper limbs (summary by Tsai et al., 2017). 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

Absent patellar reflexes

MedGen UID:: 643630
•Concept ID:: C0558844
•: Finding

Absence of the knee jerk reflex, which can normally be elicited by tapping the patellar tendon with a reflex hammer just below the patella.

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Absent Achilles reflex

MedGen UID:: 108240
•Concept ID:: C0558845
•: Finding

Absence of the Achilles reflex (also known as the ankle jerk reflex), which can normally be elicited by tapping the tendon is tapped while the foot is dorsiflexed.

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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).

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Distal lower limb muscle weakness

MedGen UID:: 324514
•Concept ID:: C1836450
•: Finding

Reduced strength of the distal musculature of the legs.

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Distal upper limb muscle weakness

MedGen UID:: 461970
•Concept ID:: C3150620
•: Finding

Reduced strength of the distal musculature of the arms.

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Hyporeflexia

MedGen UID:: 195967
•Concept ID:: C0700078
•: Finding

Reduction of neurologic reflexes such as the knee-jerk reaction.

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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.

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Difficulty walking