week 5 - DMD Flashcards
What are Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) referred to?
Xp21 dystrophies bc of genetic basis being variants in the DMD gene, which encodes dystrophin, at this locus
is DMD or BMD more severe?
DMD
incidences od DMD
approx 1:3500
incidences of BMD
approx 1:20k
When does DMD present itself in male patients?
between ages 2-4 with slowly progressive muscle weakness resulting in awkward gait, inability to run quickly, difficulty rising form the floor
How can DMD patients get up from the floor?
Gower’s sign - climbing up the legs and tight
when do most affected boys require a wheelchair by?
age 11, due to severe proximal weakness
what are more severe consequences of DMD?
lumbar lordosis, joint contractures, cardiorespiratory failure
What is the life expectancy for boys with DMD?
late teens, early 20s
Is there a cure?
no, beneficial treatments such as steroids and respiratory support in the form of continuous positive airways pressure (CPAP)
What is unusual about male calves when DMD or BMD is present?
increase in size, but mainly due to replacement of muscle fibres by fat and connective tissue - pseudohypertrophy
What about intellectual ability in DMD patients?
1/3 of boys show mild-moderate intellectual impairment, mean intelligence quotients of 83
How severe is BMD in comparison?
similar but less aggressive course, mean age of onset is 11, many remain ambulant until well into adult life, life expectancy only slightly reduced
What is the genetic basis of DMD and BMD?
X-linked recessive