Muscular Dystrophy Flashcards

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1
Q

What age does Duchenne muscular dystrophy present?

A

2-3 years

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2
Q

At what age do Duchenne muscular dystrophy patients require a wheelchair?

A

12 years

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3
Q

In Duchenne and Becker muscular dystrophy which muscles are affected most by weakness?

A

Starts in trunk but spreads to arms and legs
Legs get weak first
Hard to run, jump, or climb stairs

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4
Q

What age does Emery-Dreifuss muscular dystrophy present?

A

Ages 10 to 20 years

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5
Q

In Emery-Dreifuss muscular dystrophy which muscles are affected most by weakness?

A

Weakness starts in arms and later affects legs too
Sometimes face weakens a little

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6
Q

What are other problems associated with Emery-Dreifuss muscular dystrophy?

A

Heart problems
Contractures

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7
Q

What age does limb girdle muscular dystrophy present?

A

Childhood or later

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8
Q

In limb girdle muscular dystrophy which muscles are affected most by weakness?

A

Shoulders and hips

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9
Q

What age does facioscapulohumeral muscular dystrophy present?

A

Usually affects people ages 20 to 30 years but can happen younger

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10
Q

In facioscapulohumeral muscular dystrophy which muscles are affected most by weakness?

A

Face muscles get so weak a person cannot smile, whistle, or shut his or her eyes tight
Weakness affects legs; shoulders and upper arms

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11
Q

What age does congenital muscular dystrophy present?

A

Birth

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12
Q

In congenital muscular dystrophy which muscles are affected most by weakness?

A

Many muscles; this is sometimes called “floppy baby”

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13
Q

What are the initial labs ordered in muscular dystrophy?

A

CK, CMP, TSH, T4, ESR

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14
Q

What is the testing strategy in DMD?

A

Del/dup analysis first (80%) followed by sequencing

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15
Q

In the absence of family history, what is the chance that a person’s mother is a carrier of DMD (with an affected proband)?

A

2/3

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16
Q

What is the cardiac finding in female carriers of DMD and what percentage are affected?

A

8% develop DCM

17
Q

What is the onset of Beckers muscular dystrophy?

A

5-60 years

18
Q

What genes are associated with facioscapulohumeral muscular dystrophy?

A

DUX4 (AD) part of the D4Z4 macrosatellite repeat
SMCHD1 (<5%)

19
Q

What gene causes oculopharyngeal muscular dystrophy?

A

PABPN1 (AD)

20
Q

What are the features of oculopharyngeal muscular dystrophy?

A

Affects eyelids, throat, facial, and limbs
Difficulty swallowing and keeping eyes open
Onset 40-50s

21
Q

What is the genetic cause of myotonic dystrophy type 1 (DM1)?

A

CTG trinucleotide repeat in the DMPK gene (AD)

22
Q

What is the presentation of MILD myotonic dystrophy type 1 (DM1)?

A

Mild myotonia
Normal life span
Onset 20-70

23
Q

What is the presentation of CLASSIC myotonic dystrophy type 1 (DM1)?

A

Cataracts
Baldness
Muscle weakness and wasting
Myotonia
Cardiac conduction issues
Shortened life span
Onset 10-30 years

24
Q

What is the presentation of CONGENITAL myotonic dystrophy type 1 (DM1)?

A

Hypotonia at birth
Respiratory insufficiency and early death
ID

25
Q

What are the CTG repeat lengths in myotonic dystrophy?

A

Premutation: 35-49
Mild: 50-150
Classic: 100-1000
Congenital: >1000

26
Q

What is the genetic cause of myotonic dystrophy Type 2?

A

CCTG repeats in the CNBP gene (AD)

27
Q

What is the CK level in DMD/BMD

A

CK up to 20X normal

28
Q

What percentage of LGMD is AR and what are the two most common genes associated with the condition?

A

90%

CAPN3
DYSF

29
Q

What is pleiotrophy?

A

Mutations in the same gene with different phenotypes?
e.g. LGMD2 and Myoshi distal myopathy

30
Q

What are some classical clues of LGMD hip girdle?

A

Falls on uneven surfaces
Need to use arms on a chair/table to pull self up
Cannot get out of booths/trucks

31
Q

What are some classical clues of LGMD shoulder girdle?

A

Uses elbows to feed self
Cannot lift objects (grocery bags)

32
Q

What are the genetic causes of Emery-Dreifuss MD?

A

X-linked:
EMD
FHL1

AD/AR:
LMNA