Muscle Diseases Flashcards
Gross motor delay, weakness, delay in walking
DMD
Often dominant inheritance,
progressive weakness,
CK is
Dystrophy due to abnormal nuclear function, organization or transcription
Ex: FSHD
Myopathies usually have __________ muscle weakness
diffuse or proximal
weakness starts in teens, early adulthood, commonly ASYMMETRIC, bilateral facial weakness (eyes), scapular winging, near normal CK, other organ system involvement
Facioscapulohumeral muscular dystrophy (FSHD)
If DTR are increased, then…
neuromuscular problem is in brain/spinal cord
inherited in any pattern, Diffuse weakness in infancy/prenatally, all muscles affected including extra-ocular, normal CK, stable or slowly progressive course
Congenital myopathies
Hypotonia, diffuse weakness, contractures, opthalmoplegia, scoliosis, resp insufficiency, normal cognition, rare cardiomyopathy
Congenital myopathies
If tone is increased, then…
neuromuscular problem is in brain/spinal cord
Dystrophies of nuclear transcription, nuclear membrane have _______ CK
near-normal CK
FSHD is _________ inheritance
Autosomal dominant
Most disorders of contractile mechanism
Congenital myopathies
Inherited disorders characterized by progressive degeneration/regeneration
Muscular dystrophies
mismatch between injury/repair
Late onset signs of DMD
Speech delay, articulation problems, cognitive delay
X-linked muscular dystrophies
Duchenne, Becker
Transcription of DUX4
FSHD
Allelic to DMD
BMD (same gene involved)
Deletion within 4q35, decreased methylation of D4Z4, transcription of DUX4
FSHD1
Elevated CK indicates
Membrane stability/repair dysfunction
Usually recessive or x-linked, Progressive proximal to distal weakness, loss of muscle with fibrosis and fat replacement, CK >5x normal
Dystrophy due to membrane defect
Ex: Duchenne muscular dystrophy
Weakness around age 3, progressive to wheelchair around age 12, calf hypertrophy
DMD
SMCHD1 mutation in 18p11.32 gene responsible for methylation of D4Z4 long repeat, transcription of DUX4
FSHD2
weakness in childhood, cardiomyopathy, muscle fatigue/cramping
BMD
Core myopathies associated with genes
RYR1, SEPN1
What gene is associated with all types of congenital myopathies?
RYR1 - Ryanodine receptor - release of calcium to initiate contraction
Gene mutation also risk for malignant hyperthermia
Dystrophin mutations
Large deletions, duplications
Point mutation
