Genetics Flashcards
What is an example of an X-linked recessive neuro disease?
Duchenne muscular dystrophy
What is an example of an AD neuro disease?
Huntington’s
What are some examples of neuro diseases displaying heterogeneity/are multifactorial?
Alzheimer’s
MS
What does DMD cause?
Delay in motor development
Wheelchair bound by 10-12y
Death from involvement of respiratory and cardiac muscle in 20s
Male incidence 1:3000
When and where does the onset of DMD occur?
~3-4 years in the pelvic and shoulder girdles
What feature occurs in DMD and Becker muscular dystrophy?
Calf hypertrophy
Why does DMD occur?
Deletion of dystrophin gene in 70% DMD boys
Point mutations, small insertions and deletion in remaining 30%
How is DMD diagnosed?
Developmental delay in boys Muscle weakness- Gower's, toe walking Raised CK EMG Muscle Biopsy Molecular genetic testing
What may be included in a DDx of DMD?
Autosomal recessive limb girdle muscular dystrophies-some caused by sarcoglycan deficiencies
What carrier testing occurs in DMD?
Identify mutation in affected boy
Test for mutation in female relatives wishing to know status
Female carriers of dystrophin mutations can be offered prenatal/pre-gestational testing
What histological findings are seen in DMD?
No spinal cord or nerve abnormality
Muscle tissue has extensive granulation and the sarcolemma is broken down and destroyed
What is Huntington’s disease?
AD progressive neurodegenerative disorder
Incidence 1:20000
What happens in Huntington’s disease?
Onset between 30-50
Involuntary movements
Dementia
Progression to severe dependency and death over 15-20 years
What is the penetrance of Huntington’s?
Age dependant (variable)
What are some early clinical signs of Huntington’s?
Clumsiness Agitation Irritability Apathy Anxiety Disinhibition Delusions/Hallucinations Abnormal eye movements Depression