Haptoglobin frequencies in Jewish communities.

The variation of the haptogIobins of human plasma was shown by Smithies (1955) and Smithies & Walker (1956, 1956) to be a Mendelian trait controlled by two alleles. These two alleles, Hpl and Hp2, co-exist generally in human populations, and their relative proportions exhibit geographic variation. Additional haptoglobin variants have been detected, but their genetic relationships to the first two alleles are not clearly established. The discovery of this polymorphic system added yet another tool to the battery of biochemical tests available to the anthropologist and hence was followed up by a series of extensive studies, in which the haptoglobin frequencies in most of the major ethnic groups were mapped (see Sutton, Matson, Robinson & Koucky, 1959, for earlier references; Allison & Barnicot, 1960; Baitsch, Meier, Schoeller & Kahlich-Koenner, 1960; Lange, 1961 ; Moullec, Fine & Linhard, 1960a, b ; Baitsch, Liebrich, Pinkerton & Mermod, 1961a,b; Blumberg & Gentile, 1961 ; Bennett, Auricht, Gray, Kirk & Lai, 1961; Parker & Bearn, 1961). While the haptogIobins of the three common phenotypes are capable of forming complexes with haemoglobin, the plasma of types 1-1 and 2-1 appears to bind more haemoglobin per unit volume than that of the 2-2 homozygote (Nyman, 1958). It has been suggested that this reaction may fulfil a physiological function in various acquired and inherited haemolytic conditions, and it is plausible that the Hpl allele, because of its higher Hb-absorptive capacity may be selectively favoured in populations where such conditions are common (cf. Sutton et at. 1959). The different Jewish groups, which have been scattered for a t least 80 to 90 generations over numerous countries in three continents were doubtlessly exposed to different selective agents by their diverse environments. From time to time these Jewish groups must have experienced admixtures of various types and amounts of genes from the autochthonous populations surrounding them. However, the strict observance over long periods of a religious code forbidding intermarriage with gentiles and granting proselytism only as a comparatively rare favour appears to have ensured a large measure of reproductive isolation to each one of these communities. Wherever population size dwindled, gene frequencies may have responded with rapid drift, and inbreeding tendencies (Goldschmidt, Ronen & Ronen, 1960) may have created an ‘isolate effect ’ in large congregations. The differences as we12 as the affinities between the Jewish groups have aroused considerable interest (Gurevitch and collaborators, 1951-56 ; Margolis, Gurevitch & Hasson, 1957; Sachs & Bat-Miriam, 1957; Mourant, 1954, 1959; Szeinberg & Sheba, 1958;