Genetic Diseases Flashcards
What pattern of inheritance does Duchenne muscular dystrophy (DMD) follow?
X-linked recessive
Where is delay in motor movement and muscle weakness usually present in DMD?
Pelvic and shoulder girdles
When does death typically occur in DMD and why?
Between 20 and 30 years old
Cardiorespiratory muscle dysfunction
List some clinical features of DMD
Thigh muscle wasting
Gower sign
Exaggerated lumbar lordosis
Which protein is deficient in DMD? Why is it important?
Dystrophin
Connects contractile cell elements together - without it muscles can’t renew or operate
What type of genetic abnormalities affects the dystrophin gene in DMD?
Large deletions (70%) Point mutations, small insertions and deletions (30%)
List investigations for DMD
Serum CK (raised)
Electromyography
Muscle biopsy
Genetic screen
Asymptomatic carriers of the DMD gene can have raised serum CK. True/False?
True
When is the usual onset for Huntington disease?
Between 30-50 years old but can vary
List the clinical features of Huntington disease
Involuntary, semi-purposeful movements Clumsiness Irritability/agitation Apathy Delusions/hallucinations Depression
What inheritance pattern does Huntington disease follow?
Autosomal dominant
What happens to the basal ganglia in the brain in Huntington disease?
Caudate nucleus atrophy
What is the molecular genetic defect in Huntington disease?
Extra CAG codons (extra glutamine produced)
Alzheimer disease is a multifactorial genetic disease. Which inheritance patterns can it follow?
Autosomal dominant (10%) Trisomy 21 (with Down syndrome)