Paeds Written - Genetics Flashcards
Pathophysiology of muscular dystrophies
X linked recessive
Deletion of dystrophin gene
Dystrophin deficiency –> myocyte necrosis –> release of CK
Duchenne muscular dystrophy - clinical features
progressive proximal muscle weakness Delayed walking waddling gait often unable to climb stairs alone Gower's sign - uses arms to stand from squatted position Calf pseudo hypertrophy intellectual impairment (30%)
Diagnosis of Duchenne’s
Genetic testing = definitive
Creatine kinase - raised
Muscle biopsy - previously used
Prognosis & complications of Duchenne’s
Most unable to walk by 12yo
Dilated cardiomyopathy & resp failure
Survive to ~25-30yo
Differences between Duchenne’s & Becker
Similar Sx BUT Becker’s
- milder
- progresses more slowly
- normal life expectancy
Genetics of Myotonic dystrophy
Autosomal dominant
Trinucleotide repeat disorder
Exhibits genetic anticipation
Subtypes of Myotonic dystrophy
Type 1 - more common, more severe, muscle weakness + wasting of legs, hands, neck, face
Type 2 - shoulders, elbows, hips
+ cataracts, learning disabilities, arrhythmias
Spinal muscular atrophy - presentation
Progressive weakness + wasting of skeletal muscles
Charcot-Marie tooth disease - Presentation
symmetrical
slowly progressive
distal muscle wasting
+ high arched foot?
Marfan’s syndrome - presentation
Tall, slender Disproportionately long limbs Long, narrow face High arched palate Joint hypermobility Scoliosis Flat feet Pectus excavatum
Complications / Associations in Marfan syndrome
Cardiac abnormalities - mitral prolapse, aortic aneurysm, aortic dissection
Visual disturbance - cataracts, lens dislocation
