When geneticists want to uncover genetic associations for a particular disease, they can compare specific genetic variants (alleles) present in a large group of individuals with the disease to those present in a large group without the disease. The basic logic is that variants over-represented- or only found in- the disease population, are associated with that disease. Then the work begins to uncover what functional differences exist between individuals.

The interesting thing is that people can be segregated on a number on quantitative traits. If you can measure it, you can look for genetic associations, given you have enough people and accurate enough measurements. This is what a group has recently done for short-term memory capability.

Using a large number of Swiss, German and Serbian individuals, the researchers tested their short-term memory by showing them six series of 5 semantically unrelated nouns (1 per second). Individuals were then asked to recall the words, where the number of correctly recalled words acted as a measurement of their memory. Performing a genetic association study, alleles of the gene SCN1A were associated with good versus poor instant recall ability.

The study takes it one step further because they measure the activity o that gene in individuals with different alleles. The gene, which is expressed in the brain, has significantly different activity dependent on which allele is present.

So not only are particular alleles associated with good short-term memory, but it’s clear that there are differences in expression. Exactly what the functional difference is, that leads to good versus bad memory, will still need to be uncovered. Also, it is likely that the specific genetic variations that the study uncovered are not the actual functional mutations, but rather very close to them, so further work will require uncovering all the details of functional variation in the gene.

Image: Kindershop on Flickr

Citation:

Papassotiropoulos, A., Henke, K., Stefanova, E., Aerni, A., Müller, A., Demougin, P., Vogler, C., Sigmund, J., Gschwind, L., Huynh, K., Coluccia, D., Mondadori, C., Hänggi, J., Buchmann, A., Kostic, V., Novakovic, I., van den Bussche, H., Kaduszkiewicz, H., Weyerer, S., Bickel, H., Riedel-Heller, S., Pentzek, M., Wiese, B., Dichgans, M., Wagner, M., Jessen, F., Maier, W., & de Quervain, D. (2009). A genome-wide survey of human short-term memory Molecular Psychiatry DOI: 10.1038/mp.2009.133