From the paper:
Furthermore, they indicate the existence of a genetic heterogeneity in Italy, in accordance with previous studies on classical markers (Piazza et al., 1988) and Y-chromosome (Capelli et al., 2007; see also Francalacci and Sanna, 2008). On the contrary, a substantial homogeneity was detected among Greek groups (Supporting Information Table S3), which is congruent with the only previous genetic study conducted in Greece on a multiregional scale (Di Giacomo et al., 2003).
The occurrence of lactase persistence in Greece and Southern Italy is virtually the same, which is not very surprising given the origins of the latter population.
American Journal of Human Biology Volume 21 Issue 2, Pages 217 - 219, doi:10.1002/ajhb.20851
Tracing the distribution and evolution of lactase persistence in Southern Europe through the study of the T-13910 variant
Paolo Anagnostou et al.
We investigated the occurrence and intra-allelic variability of the T-13910 variant located upstream of the lactase gene in 965 individuals from 20 different locations of Italy and Greece. The T-13910 frequency ranges from 0.072 (Sardinia) to 0.237 (North-East Italy), with a statistically significant difference between North-East Italians and other Italian populations. The comparison of the lactose tolerance predicted by T-13910 and that assessed by other studies using physiological tests shows a one-way statistically significant discrepancy that could be due to sampling differences. However, the possible role of other genetic factors underlying lactase persistence is worth exploring. The time of the most recent common ancestor and departures from neutrality of the T-13910 allele were assessed using three microsatellite loci. Time estimates were found to be congruent with the appearance of dairy farming in Southern Europe and the occurrence of a single introgression event. Robust signals of selection can be observed in North-East Italy only. We discuss the possible role of cultural traits and genetic history in determining these observed micro-evolutionary patterns.