Neuromuscular Flashcards
What is the most common genetic change in Charcot Marie Tooth syndrome?
17p duplication
What is another common genetic change in Charcot Marie Tooth syndrome?
PMP22
What is the phenotype of Charcot Marie Tooth syndrome?
Atrophy of muscles in legs, feet, and hands
High arched feet
Hammer toes
What percentage of SMN1 are deletions?
95%
What percentage of SMN1 mutations are de novo?
2%
What percentage of SMA cases is one parent a silent carrier?
4%
What is the problem with using copy number analysis of SMN1 for SMA?
Silent carriers are not detected
Also misses people with point mutations
What percentage of SMN1 are point mutations?
5%
In what NM disorder is onset <5 years, wheelchair <13 years, and lifespan 20-30 years?
DMD
What are features of DMD
Gower sign
Pseudohypertrophy of calf
Elevated CPK
Muscle weakness starts in proximal legs/pelvis
Awkward gait
Possible motor or developmental delay
Eventual respiratory issues
What is the Gower sign?
The child assumes the hands-and-knees position and then climbs to a stand by “walking” his hands progressively up his shins, knees, and thighs
What percentage of DMD is due to deletions?
80%
What is the testing strategy with DMD?
Start with del/dup analysis followed by sequencing
What cardiac finding occurs in DMD carriers and what percentage are affected?
DCM 8%
What is the age of onset of BMD?
5-60 years
What differentiates the muscular presentation in BMD versus DMD?
Preservation of neck flexor muscle strength in BMD
What genes are affected in Facioscapulohumeral Muscular Dystrophy?
DUX4 (AD)
SMCHD1 (<5%)
What muscles are affected in Facioscapulohumeral Muscular Dystrophy?
Face, shoulder blades, upper arms, abs, lower legs
What is the onset of Facioscapulohumeral Muscular Dystrophy and how long do patients live?
Onset <20 years
Normal life span
What is the mode of inheritance of Limb Girdle Muscular Dystrophy Type I and II?
Type I: AD
Type II: AR
What is the phenotype of Limb Girdle Muscular Dystrophy?
Affects proximal muscles around hips and shoulders
Waddling gait, trouble standing and with stairs, raising arms, may eventually need mobility assistance
Cardiomyopathy associated with some types
Elevated CK
What gene causes Oculopharyngeal Muscular Dystrophy?
PABPN1 (AD)
What are the features of Oculopharyngeal Muscular Dystrophy?
Affects eyelids, throat, facial, and limbs
Difficulty swallowing and keeping eyes open, some mobility issues
Onset 4-5 decade
What are the features of Emery Dreifuss Muscular Dystrophy?
Early contractures in elbows, neck and heels are common
Wasting of shoulders, upper arms, and calves
Cardiac conduction issues may show as fainting
When does Emery Dreifuss Muscular Dystrophy occur?
Onset by 10 years