Genetics of the Chuetas (Majorcan Jews): A comparative study

Human Biology, Jun 1997 by Picornell, Antonia, Castro, Jose A, Ramon, M Misericordia

Abstract A study of the Chueta population has been carried out to establish the genetic relationships between the Chuetas and other Jewish and non-Jewish circum-Mediterranean populations and to identify which markers discriminate better between these populations. The analyses used were principal components analysis, factorial analysis of correspondences, and stepwise discriminant analysis. The results indicate that most of the Jewish communities resemble each other and other Middle Eastern populations, because of their common origin, but they also have affinities with their host peoples. The results also agree with those of most researchers in the importance of G6PD, FY, and MN as geographic markers and in the role of HP, GLO], and Rh as indicators the Middle Eastern origin of the Jews but differ with respect to the geographic pattern of ABO. Moreover, the Jewish origin of the Chuetas remains evident in their genetic pool, although they resemble their neighboring populations more than other Jewish populations. Finally, HP, G6PD, ABO and Rh are the most important variables in determining the position of the Chuetas with respect to other Jewish and non-Jewish populations.

KEY WORDS: CHUETAS, MULTIVARIATE ANALYSIS, JEWISH POPULATIONS, GENE FREQUENCIES

ANTONIA PICORNELL,1 JOSP A. CASTRO, AND M. MISERICORDIA RAMON The Chuetas are descendants of the Jewish inhabitants of Majorca (Balearic Islands). Their origin goes back to the Sephardic communities that lived during the Spanish diaspora. The Majorcan Jews remained in Spain after the expulsion of Spanish Jews by the Catholic monarchs in 1492. Their conversion had been forced upon them by local social and ecclesiastic pressures (1391-1435). Despite their conversion, they were discriminated against and isolated from the originally Christian Balearic population until the middle of the twentieth century (Braunstein 1936; Moore 1976; Laub and Laub 1987).

The classical genetic polymorphisms used in most studies of Jewish and/or Mediterranean populations have been studied in the Chueta community: enzymatic polymorphisms (Picornell et al. 1990), blood groups (Picornell et al. 1991), and serum proteins (Picornell et al. 1992, 1994; Nevo et al. 1996). The results show that the Chueta population differs from the nonChueta Majorcan population and that some alleles are indicative of the Jewish origin of this population (e.g., HP*2FS, ORM*S1, and ORM*S2), although the frequencies of other alleles in the Chueta population show substantial Spanish influence (e.g., PI*S).

Multivariate analysis is a set of powerful statistical techniques that permit all the variables under study to be taken into account at the same time and for the contribution of each variable to be detected in the description of a phenomenon. Principal components analysis and factorial analysis of correspondences are useful in data analysis and representation, whereas discriminant analyses are mainly used for classification (Cuadras 1981).

The application of multivariate analyses in human population studies, mainly principal components analysis, has increased the possibilities of description and interpretation of such studies. Multivariate analysis was used in studies in Italy (Piazza 1990), in the Iberian Peninsula (Bertranpetit and Cavalli-Sforza 1991), and in the Basque population (Arrieta et al. 1990; Calafell and Bertranpetit 1994) and in studies on demic expansions of human populations (Cavalli-Sforza et al. 1993). Miguel et al. (1990) used principal components analysis to establish genetic relationships within the Balearic population and between this population and other world populations.

The present study was designed (1) to establish genetic relationships between Chuetas and other Jewish and non-Jewish circum-Mediterranean populations by means of hematologic genetic markers and (2) to identify which markers discriminate better between these populations.

Materials and Methods

A sample of 443 individuals from the Chueta community identified by 1 of 15 surnames (Aguilo, Bonnin, Cortes, Forteza, Fuster, Marti, Miro, Pico, Pina, Pomar, Segura, Tarongi, Valenti, Valleriola, and Valls) was studied, and the phenotypes for the following markers were determined: blood groups ABO, MNSs, P, Rh, Kell (KEL), and Duffy (FY); red cell enzymes glucose6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (PGD), acid phosphatase (ACP]), phosphoglucomutase 1 (PGM]), glyoxalase 1 (GLOI), and adelynate kinase ); serum proteins haptoglobin (HP) and group specific component (GC).

The detailed methods used are described elsewhere (Picornell 1992; Picornell et al. 1990, 1991, 1992). Moreover, a set of data from the literature, which included the preceding 14 polymorphic systems in 26 populations, were used. The lack of data in some populations meant that the P, FY, G6PD, GLO], and GC systems were not included in all the analyses. The system MNSs was separated in the analyses because in the literature there were no data on haplotypes for some populations.