In a recent study of a large sample of Icelanders, researchers identified a correlation between the presence of a mutation on the gene ABCA7 and Alzheimer disease.
Iceland is a veritable laboratory for genetic research: founded more than a thousand years ago by a small number of explorers and still isolated to this day, the Icelandic population has very low genetic diversity, which facilitates the identification of relations between diseases and genetic mutations. In addition, the history of the population can be traced thanks to the quality of conserved genealogical data and the knowledge the inhabitants have of their origins.
In the study entitled "Loss-of-function variants in ABCA7 confer risk of Alzheimer's disease," published on March 25, 2015, in Nature Genetics by several researchers, including Pr. Harald Hampel of Pierre and Marie Curie University / IMA2 / Institut du Cerveau - ICM, the scientists showed that an alteration in the gene ABCA7 might be a risk factor for Alzheimer's disease.
The ABCA7 protein is strongly expressed in the central nervous system and is part of a family of proteins involved in membrane transport.
The study was performed in a cohort of more than 2600 Icelanders, including healthy subjects and patients with various neurodegenerative disorders. The authors of the study include, notably, Pr. Harald Hampel, Kari Stefansson and his colleagues in deCODE Genetics, a subsidiary of Amgen based in Reykjavik.
The researchers also looked for genetic variants identified in cohorts of patients from other countries such as Germany, Finland, Norway and the USA, in which they were able to identify the same mutations in Alzheimer disease patients. The carriers of these rare variants had a mean 1.73 times greater probability of developing the disease.
According to Pr. Harald Hampel and the founder of deCIDE Genetics, Kari Stefansson, this study clearly demonstrates the power of the sequencing techniques.
At present, the researchers do not understand how the ABCA7 protein contributes to Alzheimer disease. But these studies open the way for new and more precise methods for diagnosing Alzheimer disease and other neurodegenerative disorders.
Pr. Harald Hampel occupies the AXA-UPMC Chair "Anticipate Alzheimer disease" at the Sorbonne Universities.
