spinal mus·cu·lar at·ro·phy type I
[MIM*253300] the early infantile form, characterized by profound muscle weakness and wasting with onset at or shortly after birth; death occurs usually before 2 years of age. Autosomal recessive inheritance, caused by mutation in the survival motor neuron gene (SMN1) on 5q. About half of affected patients are also missing both homologues of a neighboring gene that encodes neuronal apoptosis inhibitory protein (NAIP), the loss of which is thought to influence the severity of the disease.
Farlex Partner Medical Dictionary © Farlex 2012
spinal muscular atrophy type 1
An autosomal recessive condition (OMIM:253300) characterised by degeneration of the anterior horn cells of the spinal cord, leading to symmetrical muscle weakness and atrophy. Disease severity is inversely proportional to the copy number of SMN2, a copy gene which predominantly produces exon 7-skipped transcripts and only low amounts of full-length transcripts that encode for a protein identical to SMN1. Only about 4% of SMA patients bear one SMN1 copy with an intragenic mutation. SMA1 is the severest form of the SMAs, with onset before age 6 months. Infants never achieve the ability to sit.
Molecular pathology
Defects of SMN1, which encodes a survival motor neuron protein, cause spinal muscular atrophy types 1–4.Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
Werdnig-Hoffmann disease
Spinal muscle atrophy, see there. McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
Hoffmann,
Johann, German neurologist, 1857-1919. Hoffmann muscular atrophy - progressive dysfunction of the anterior horn cells in the spinal cord and brainstem cranial nerves. Synonym(s): infantile spinal muscular atrophy
Hoffmann phenomenon - excessive irritability of the sensory nerves to electrical or mechanical stimuli in tetany.
Hoffmann sign - in latent tetany, mild mechanical stimulation of the trigeminal nerve causes severe pain. Synonym(s):
Hoffmann reflex Werdnig-Hoffmann muscular atrophy - see under
Werdnig
Werdnig,
Guido, Austrian neurologist, 1862-1919. Werdnig-Hoffmann muscular atrophy - progressive dysfunction of the anterior horn cells in the spinal cord and brainstem cranial nerves, with profound weakness and bulbar dysfunction. Synonym(s):
infantile spinal muscular atrophy;
Werdnig-Hoffmann disease Medical Eponyms © Farlex 2012