U.S. flag

An official website of the United States government

Format

Send to:

Choose Destination

X-linked distal spinal muscular atrophy type 3(SMAX3; HMNX)

MedGen UID:
335168
Concept ID:
C1845359
Disease or Syndrome
Synonyms: ATP7A-Related Distal Motor Neuropathy; NEURONOPATHY, DISTAL HEREDITARY MOTOR, X-LINKED; NEUROPATHY, DISTAL HEREDITARY MOTOR, X-LINKED; SPINAL MUSCULAR ATROPHY, DISTAL, X-LINKED RECESSIVE
SNOMED CT: X-linked distal hereditary motor neuropathy type 3 (766764008); X-linked distal spinal muscular atrophy type 3 (766764008); ATP7A (ATPase copper transporting alpha) related distal motor neuropathy (766764008)
Modes of inheritance:
X-linked recessive inheritance
MedGen UID:
375779
Concept ID:
C1845977
Finding
Source: Orphanet
A mode of inheritance that is observed for recessive traits related to a gene encoded on the X chromosome. In the context of medical genetics, X-linked recessive disorders manifest in males (who have one copy of the X chromosome and are thus hemizygotes), but generally not in female heterozygotes who have one mutant and one normal allele.
 
Gene (location): ATP7A (Xq21.1)
 
Monarch Initiative: MONDO:0010338
OMIM®: 300489
Orphanet: ORPHA139557

Definition

A rare distal hereditary motor neuropathy with characteristics of slowly progressive atrophy and weakness of distal muscles of hands and feet with normal deep tendon reflexes or absent ankle reflexes and minimal or no sensory loss, sometimes mild proximal weakness in the legs and feet and hand deformities in males. [from SNOMEDCT_US]

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).
Unsteady gait
MedGen UID:
68544
Concept ID:
C0231686
Finding
A shaky or wobbly manner of walking.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Distal sensory impairment
MedGen UID:
335722
Concept ID:
C1847584
Finding
An abnormal reduction in sensation in the distal portions of the extremities.
Abnormal peripheral nervous system morphology
MedGen UID:
892389
Concept ID:
C4025831
Anatomical Abnormality
A structural abnormality of the peripheral nervous system, which is composed of the nerves that lead to or branch off from the central nervous system. This includes the cranial nerves (olfactory and optic nerves are technically part of the central nervous system).
Spinal muscular atrophy
MedGen UID:
7755
Concept ID:
C0026847
Disease or Syndrome
Spinal muscular atrophy (SMA) is characterized by muscle weakness and atrophy resulting from progressive degeneration and irreversible loss of the anterior horn cells in the spinal cord (i.e., lower motor neurons) and the brain stem nuclei. The onset of weakness ranges from before birth to adulthood. The weakness is symmetric, proximal > distal, and progressive. Before the genetic basis of SMA was understood, it was classified into clinical subtypes based on maximum motor function achieved; however, it is now apparent that the phenotype of SMN1-associated SMA spans a continuum without clear delineation of subtypes. With supportive care only, poor weight gain with growth failure, restrictive lung disease, scoliosis, and joint contractures are common complications; however, newly available targeted treatment options are changing the natural history of this disease.
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.
EMG: neuropathic changes
MedGen UID:
867363
Concept ID:
C4021727
Finding
The presence of characteristic findings of denervation on electromyography (fibrillations, positive sharp waves, and giant motor unit potentials).

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVX-linked distal spinal muscular atrophy type 3
Follow this link to review classifications for X-linked distal spinal muscular atrophy type 3 in Orphanet.

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...