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MM 10 - Human Genetic Variability + Its Consequences (i) (Aneuploidy…
MM 10 - Human Genetic Variability + Its Consequences (i)
Intro
2 human genomes
99.9% identical, 0.1% different
Moore's law
in computers ever 2 years processor speeds double for the same cost (i.e. human genome sequencing should;d drop in price)
cost per genome followed Moore's law until 2007, then price dropped dramatically
now approx 400 euro
same price as MRI with much more info
but high analytic cost
sexual reproduction introduces genetic differences into pop
normal, allows for evolution, adaptation, protection from extinction
Aneuploidy
large scale genetic variation
usually causes large change in gene expression
clinical consequences: non-viable embryo, learning disabilities, developmental delay
abnormal chromo no.
extra (trisomy) - increase protein synthesis
missing (monosomy) decrease protein synthesis
incidence = rare (1 in 1000)
viable trisomies
Patau syndrome (13)
Edward's syndrome (18)
Down's syndrome (21)
Kleinefelter's (XXY)
only viable monosomy = Turner's syndrome (1 sex chromo - X)
non-viable aneuploidies can grow for some time before miscarriage
can be detected via blood test @ end of 1st trimester
Translocations/Transversions
large scale
during meoisis, 2 different chromos exchange DNA
x2 as common as aneuploidies (1 in 500)
usually not as severe as aneuploidies
no clinical relevance as long as there's NOT NET GAIN/LOSS OF DNA
UNLESS BREAKPOINT IS IN MIDDLE OF GENE (disrupts gene sequence)
Copy Number Variants (CNVs)
large scale
large sections (>1000 bps) of DNA duplicated (more protein synthesis) or deleted (less protein synthesis)
everyone carries multiple CNVs, most benign
1000000 = clinical pathology
ADHD, autism, epilepsy, intellectual disabilities