December 21, 2012

New isolates from Friuli-Venezia Giulia region

European Journal of Human Genetics advance online publication 19 December 2012; doi: 10.1038/ejhg.2012.229

Genetic characterization of northeastern Italian population isolates in the context of broader European genetic diversity

Tõnu Esko et al.

Population genetic studies on European populations have highlighted Italy as one of genetically most diverse regions. This is possibly due to the country’s complex demographic history and large variability in terrain throughout the territory. This is the reason why Italy is enriched for population isolates, Sardinia being the best-known example. As the population isolates have a great potential in disease-causing genetic variants identification, we aimed to genetically characterize a region from northeastern Italy, which is known for isolated communities. Total of 1310 samples, collected from six geographically isolated villages, were genotyped at >145 000 single-nucleotide polymorphism positions. Newly genotyped data were analyzed jointly with the available genome-wide data sets of individuals of European descent, including several population isolates. Despite the linguistic differences and geographical isolation the village populations still show the greatest genetic similarity to other Italian samples. The genetic isolation and small effective population size of the village populations is manifested by higher levels of genomic homozygosity and elevated linkage disequilibrium. These estimates become even more striking when the detected substructure is taken into account. The observed level of genetic isolation in Friuli-Venezia Giulia region is more extreme according to several measures of isolation compared with Sardinians, French Basques and northern Finns, thus proving the status of an isolate.



Mauri said...

It would be more interesting to see structures INSIDE national populations rather than comparing North Italian isolates with Rssians and Estonians as a whole. Doing like they do there is grawbacks, like

- we dont know how the national average is completed (see below)

- we find out nothing about the population structure inside each national populations

Collecting data from isolated villages from each country we could estimate the diversity composition of each country. It could be real widepread diversity or could mirror several distinct ethnic groups. I would make a bet that for example in Estonian the diversity is a result of Estonian and Russian subpopulations, speaking Estonian and Russian languages. Looking local (villages) results this could be seen.

By comparing internally national results of LD and homozygosity we could estimate a) is the overall diversity real b) the ratio between samples collected for the group G (general subpopulations) and isolations.

Making those comparisons it would be later possible to built a historical view from national structures and even judge present studies and result to new studies in future and see the national sampling quality.

truth said...

Are the samples available ?