KIBRA genetic polymorphism influences episodic memory in Alzheimer's disease, but does not show association with disease in a Japanese cohort.
OBJECTIVE
A single-nucleotide polymorphism (SNP) in the KIBRA gene, rs17070145, was reported to be significantly associated with episodic memory in cognitively normal cohorts. This observation has expanded genetic studies on KIBRA to Alzheimer's disease (AD). Importantly, the association between KIBRA and episodic memory in AD has never been addressed. In this study, we investigated whether the KIBRA rs17070145 SNP influences AD episodic memory and the disease in a Japanese cohort.


METHODS
Blood samples from 346 AD patients and 375 normal cognitive controls were collected and genotyped for rs17070145. Episodic memory was measured in 32 AD patients, diagnosed for the first time, by use of the Rivermead Behavioral Memory Test (RBMT).


RESULTS
We found that KIBRA C allele carriers scored significantly lower than KIBRA non-C carriers on both RBMT total profile score (p = 0.042, effect size = 0.84) and RBMT total screening score (p < 0.001, effect size = 1.42). The KIBRA gene did not show association with AD in our Japanese cohort.


CONCLUSIONS
Our results evidence a strong association between the KIBRA gene and episodic memory impairment in AD, but show no influence on AD in our Japanese cohort. We propose that KIBRA might have an effect similar to cognitive reserve.
Hayashi
Noriyuki
N
Department of Psychiatry, Osaka University Graduate School of Medicine, Japan.
Kazui
Hiroaki
H
Kamino
Kouzin
K
Tokunaga
Hiromasa
H
Takaya
Masahiko
M
Yokokoji
Mikiko
M
Kimura
Ryo
R
Kito
Yumiko
Y
Wada
Tamiki
T
Nomura
Keiko
K
Sugiyama
Hiromichi
H
Yamamoto
Daisuke
D
Yoshida
Tetsuhiko
T
Currais
Antonio
A
Soriano
Salvador
S
Hamasaki
Toshimitsu
T
Yamamoto
Mitsuko
M
Yasuda
Yuka
Y
Hashimoto
Ryota
R
Tanimukai
Hitoshi
H
Tagami
Shinji
S
Okochi
Masayasu
M
Tanaka
Toshihisa
T
Kudo
Takashi
T
Morihara
Takashi
T
Takeda
Masatoshi
M
D000368:Aged; D000544:Alzheimer Disease / Q000208:ethnology / Q000235:genetics*; D000704:Analysis of Variance; D044466:Asian People / Q000235:genetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007564:Japan; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010750:Phosphoproteins; D020641:Polymorphism, Single Nucleotide; D011506:Proteins / Q000235:genetics*; D012016:Reference Values
D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011506:Proteins; C513637:WWC1 protein, human