**3. The Situation on the European Continent**

Despite the fact that the potato blight also struck continental Europe and the unfavourable climatological circumstances (temperature, humidity) between 1845 and 1847 were comparable among Western European countries, continental Europe was less affected than Ireland. When plotting the C282Y allele frequencies of the various European countries (Belgium, The Netherlands, France, Switzerland, Germany) against the excess mortality of the years 1845–1847 and the decline in potato yields, a good correlation (*y* (excess mortality per million) = −32.42 + 9.22*x* (C282Y allele frequency, %), *r* 2 = 0.98) was obtained (Table 1). As the Hp phenotype frequency shows more limited differences among European countries [11], no significant correlation between the Hp 2 allele frequency and the excess in mortality was found.

Also in France, a country with important Celtic influences, a marked correlation between the C282Y mutation frequency and mortality was observed for the various departments. When comparing the 1846 mortality among the population aged 30–35 years with the C282Y allele frequency for the various departments (Figure 1), a marked correlation was found, which resembles the one found for Western Europe. Higher C282Y frequencies were associated with higher mortality rates. Both in the 1841 and 1851 French census [20], the effect of the C282Y allele frequency on mortality of 30 year old subjects was greatly reduced, as evidenced by the regression coefficients (1841:0.016; 1846:0.024; 1851:0.016).

**Figure 1.** Mortality in 30–35 year old subjects in 1846 according to C282Y allele frequencies in a number of French departments. The *Y*-axis depicts the death probabilities q (*x*) for every age (*x*) computed for that period. The *X*-axis represents the C282Y allele frequency in the different departments.


**Table 1.** Overview of annual excess mortality, decline in potato yields and C282Y mutation frequency in various European countries.
