Flashcards in DNA testing in diagnosis of neurological disorders Deck (13):
What are unstable repeat expansion?
expansion of a segment of DNA within a specific gene above the threshold - usually consists of repeating units of 3 or more nucleotides eg CAG, CCG
what are unstable repeat expansion also called?
dynamic mutations -> size of the expansion is changing
the increase in expansion size from generation to generation
Huntinton disease is associated with what unstable repeat expansion, what are the effects?
CAG triplet repeat in the coding region of the HTT gene. Leads to toxin protein production Poly -Q HTT -> damages basal ganglia -> atrophy
How does Freidrich ataxia occur? when does it usually occur in individuals?
GAA triplet repeat in an intron -> impaired transcription of a Frataxin protein> onset in adolescence (unlike other disorders - mostly late onset)
People affected with HD have how many triplet repeats?
How many CAG repeats is considered normal? how many is normal mutable?
27-35 = normal mutable (may pass on to offspring)
What is the zone of reduced penetrance for HD?
36-39 CAG repeats -> individual may or may not develop the disease
Is HD autosomal, X linked? recessive or dominant?
are the spinocerebellar ataxias autosomal, X linked? recessive or dominant?
What triplet repeat is present in the spinocerebellar ataxias and what does it cause?
mutated protein that affects the functioning of the appropriate ion channel
Is Freidrich Ataxia autosomal, X linked? recessive or dominant?