Predisposition to Adult Onset Disease Flashcards
What are the main mechanisms of adult onset genetic disease?
Single gene
Chromosomal
Mitochondrial
Multifactoral
What is the mean age of onset of amyotrophic lateral sclerosis (motor neurone disease)?
55yrs
What are the clinical features of ALS?
Progressive muscle weakness, wasting and increased reflexes Limn and bulbar muscles involved Pure motor signs (with fasciculations) Cognition spared Death due to respiratory failure
What gene is involved in ALS?
Cu/Zn superoxide dismutase (SOD)
What is the primary function of SOD?
Catalyses conversion of intercellular superoxide radicals produced during normal metabolism
How many types of SOD are found in humans and where are they located?
SOD1 (cytoplasm) contain Cu and Zn
SOD2 (mitochondria) contains manganese
SOD3 (extracellular) contain Cu and Zn
What mode incidence is found in Huntington’s disease?
Autosomal dominant
What are the clinical features of Huntington’s disease?
Chorea
Athetosis
Myoclonus
Rigidity
Cognitive changes (poor planning, memory, subcortical dementia)
Personalty changes (irritable, apathetic, loss of empathy, disinhibition, self centred)
Psychiatric disease (depression, paranoia, psychosis)
What is the common onset of Huntington’s disease?
Late 30’s early 40’s but variable
What are the advantages of predictive testing?
Uncertainty of gene status removed
If negative, concerns about self and offspring reduced
If positive, can make plans for future, arrange surveillance or treatment, inform children/ decide whether to have children
What are the disadvantages of predictive testing?
If positive, removes hope, continues uncertainty, known risk to offspring, impact on self/family, potential problems with insurance/mortgage
If negative, expectations of a ‘good’ result’ and ‘survivor’ guilt
