Wednesday, September 24, 2014

"Still Alice" by Lisa Genova

Here's the Amazon description.
"Still Alice is a compelling debut novel about a 50-year-old woman's sudden descent into early onset Alzheimer's disease, written by first-time author Lisa Genova, who holds a Ph. D in neuroscience from Harvard University.

"Alice Howland, happily married with three grown children and a house on the Cape, is a celebrated Harvard professor at the height of her career when she notices a forgetfulness creeping into her life. As confusion starts to cloud her thinking and her memory begins to fail her, she receives a devastating diagnosis: early onset Alzheimer's disease. Fiercely independent, Alice struggles to maintain her lifestyle and live in the moment, even as her sense of self is being stripped away. In turns heartbreaking, inspiring and terrifying, Still Alice captures in remarkable detail what's it's like to literally lose your mind..."

Midway through reading this novel to Clare, I got to the bit where Alice gets a genetic test done for early-onset (or familial) Alzheimer's. The mutated genes in question are APP, PS1 and PS2;
"Familial Alzheimer disease is caused by a mutation in one of at least 3 genes: presenilin 1, presenilin 2 and amyloid precursor protein (APP). Other gene mutations are in study."
Naturally, I scampered across to my 23andMe/Promethease health results to check out my genome. Now, 23andMe don't screen for SNPs on those genes (I can see why!) but they do look at a late-onset Alzheimer genotype - it's the ε4 variant of the APOE gene.
"Although 40-65% of AD patients have at least one copy of the ε4 allele, ApoE4 is not a determinant of the disease - at least a third of patients with AD are ApoE4 negative and some ApoE4 homozygotes never develop the disease. Yet those with two ε4 alleles have up to 20 times the risk of developing AD."
I don't have it.


Note: how do two SNPs determine three APOE variants? (From 23andMe).

Variant:  rs429358  + rs7412 (these are the two SNPs within the APOE gene)

ε2 = T + T

ε3 = T + C

ε4 = C + C

I'm ε3/ε3 - on the  chromosome 19 pair (TT + CC). It's surprising how blasé one can be about all this once it's clear that you don't have the 'bad' allele ...