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1.  Rare Variants in Calcium Homeostasis Modulator 1 (CALHM1) Found in Early Onset Alzheimer’s Disease Patients Alter Calcium Homeostasis 
PLoS ONE  2013;8(9):e74203.
Calcium signaling in the brain is fundamental to the learning and memory process and there is evidence to suggest that its dysfunction is involved in the pathological pathways underlying Alzheimer’s disease (AD). Recently, the calcium hypothesis of AD has received support with the identification of the non-selective Ca2+-permeable channel CALHM1. A genetic polymorphism (p. P86L) in CALHM1 reduces plasma membrane Ca2+ permeability and is associated with an earlier age-at-onset of AD. To investigate the role of CALHM1 variants in early-onset AD (EOAD), we sequenced all CALHM1 coding regions in three independent series comprising 284 EOAD patients and 326 controls. Two missense mutations in patients (p.G330D and p.R154H) and one (p.A213T) in a control individual were identified. Calcium imaging analyses revealed that while the mutation found in a control (p.A213T) behaved as wild-type CALHM1 (CALHM1-WT), a complete abolishment of the Ca2+ influx was associated with the mutations found in EOAD patients (p.G330D and p.R154H). Notably, the previously reported p. P86L mutation was associated with an intermediate Ca2+ influx between the CALHM1-WT and the p.G330D and p.R154H mutations. Since neither expression of wild-type nor mutant CALHM1 affected amyloid ß-peptide (Aß) production or Aß-mediated cellular toxicity, we conclude that rare genetic variants in CALHM1 lead to Ca2+ dysregulation and may contribute to the risk of EOAD through a mechanism independent from the classical Aß cascade.
doi:10.1371/journal.pone.0074203
PMCID: PMC3775809  PMID: 24069280
2.  CALHM1 P86L polymorphism does not alter amyloid-β or tau in cerebrospinal fluid 
Neuroscience letters  2009;469(2):265-267.
Recently, the P86L alteration in CALHM1 (calcium homeostasis modulator-1) was reported to be associated with Alzheimer’s disease (AD). Moreover, the risk allele increased amyloid-β (Aβ) levels in conditioned media from cultured cells. Therefore, we hypothesized that CALHM1 P86L may modulate Aβ or tau levels in cerebrospinal fluid (CSF). Nearly 200 individuals with AD or other cognitive disorders were included for CSF analysis and CALHM1 genotyping. No significant differences in CSF levels of Aβ42, tau or phospho-tau were found across the various CALHM1 genotypes. In conclusion, we found no evidence that CALHM1 P86L is associated with altered CSF levels of the investigated AD biomarkers.
doi:10.1016/j.neulet.2009.12.011
PMCID: PMC2860374  PMID: 20005921
CALHM1; Calcium homeostasis modulator-1; Amyloid-β; Alzheimer’s disease; Cerebrospinal fluid; Biomarker; Total tau; Phospho-tau; Genotyping SNP
3.  Further analysis of previously implicated linkage regions for Alzheimer's disease in affected relative pairs 
BMC Medical Genetics  2009;10:122.
Background
Genome-wide linkage studies for Alzheimer's disease have implicated several chromosomal regions as potential loci for susceptibility genes.
Methods
In the present study, we have combined a selection of affected relative pairs (ARPs) from the UK and the USA included in a previous linkage study by Myers et al. (Am J Med Genet, 2002), with ARPs from Sweden and Washington University. In this total sample collection of 397 ARPs, we have analyzed linkage to chromosomes 1, 9, 10, 12, 19 and 21, implicated in the previous scan.
Results
The analysis revealed that linkage to chromosome 19q13 close to the APOE locus increased considerably as compared to the earlier scan. However, linkage to chromosome 10q21, which provided the strongest linkage in the previous scan could not be detected.
Conclusion
The present investigation provides yet further evidence that 19q13 is the only chromosomal region consistently linked to Alzheimer's disease.
doi:10.1186/1471-2350-10-122
PMCID: PMC2791756  PMID: 19951422

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