Fragile X syndrome
Occurs due to a trinucleotide expansion of CGG in the 5’ UTR.
This causes increased methylation of mRNA (INHIBITS IT) which causes decreased production of a specific protein known as FMR1
this protein is usually highly expressed in neurons which regulates mRNA translation into proteins.
in Fragile X syndrome there is no regulation of this pathway and too many proteins are produced
Early onset Alzheimers disease
Amyloid precursor protein (APP) mutation.
or
B/Y- secretase mutation (which causes them to become overactive
causes abnormal cleavage of amyloid precursor protein leading to excess amyloid accumulation