Gene specific analysis of variance14 with expression as a function of region, gender, and their interaction discovered 1,521 probes significant at a 1% false discovery rate (FDR; P < 0.0007). Region, namely the rural (Boutroch plus Ighrem) versus city (Anza plus Dchiera) comparison is by far the main effect in this joint analysis. Approaching 7% of all expressed genes differentiate these individuals by this conservative criterion, whereas considerably fewer than 1% of the probes show gender differences. A full list of genes is provided in Supplementary Table 1 online. Among several classes of over-represented genes for this lifestyle comparison, small nucleolar RNA genes stand out: 5 of the top 8 overall and 15 of 29 members of the SNORD family are in the highly significant list, compared with just 1 of 10 SNORA genes. There is little in the literature to indicate why this is the case, or what the physiological consequences may be, but it is interesting to note that epigenetic modification has been observed for many small nucleolar RNA genes15.
