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Spinal muscular atrophy, Ryukyuan type

MedGen UID:
Concept ID:
Disease or Syndrome
Synonym: Ryukyuan muscular atrophy
Monarch Initiative: MONDO:0010057
OMIM®: 271200

Clinical features

From HPO
Pes cavus
MedGen UID:
Concept ID:
Congenital Abnormality
The presence of an unusually high plantar arch. Also called high instep, pes cavus refers to a distinctly hollow form of the sole of the foot when it is bearing weight.
MedGen UID:
Concept ID:
Sign or Symptom
Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units.
Spinal muscular atrophy
MedGen UID:
Concept ID:
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.
MedGen UID:
Concept ID:
Anatomical Abnormality
An abnormal curvature of the spine in both a coronal (lateral) and sagittal (back-to-front) plane.
Proximal amyotrophy
MedGen UID:
Concept ID:
Disease or Syndrome
Amyotrophy (muscular atrophy) affecting the proximal musculature.

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