Sickle cell and Y DNA in Sicily

Presence of an African beta-globin gene cluster haplotype in normal chromosomes in Sicily.

Ragusa A, Frontini V, Lombardo M, Amata S, Lombardo T, Labie D, Krishnamoorthy R, Nagel RL.

I.R.C.C.S., OASI, Troina, Italy.

African admixture in Sicily has been long suspected because of the presence of the sickle gene. Nevertheless, the degree of African admixture cannot be derived from the study of HbS frequency, since this gene was most likely expanded by the selective pressure of malaria, for a long time endemic to the region. We have examined 142 individuals from the Sicilian town of Butera (12% sickle trait) to search for other markers of the globin gene cluster less likely to be selected for by malaria. The TaqI polymorphism in the intervening sequences between the two gamma genes is informative. We have found only two instances of this African marker (TaqI(-)) among 267 normal chromosomes, demonstrating that the admixture occurred at a much lower level than previously thought.

A brief look at Sicilian Y chromosomes certainly didn’t show any large amounts of sub Saharan DNA. The next item identifies sub Saharan Africa as the source for the Hb s mutation in the Med (unsurprisingly, as North Africans with some West African ancestry were among the Moors). The levels of sickle cell compared to the levels of sub Saharan admixture are very supportive of natural selection encouraging the trait to increase. The following study doesn’t detail the Y chromosomes well, but about 35% are J, 25% R, I 15%, K 10%, H 10%. (roughly). The remainder seems to be North African (mainly Berber and Arab then).

Differential Greek and northern African migrations to Sicily are supported by genetic evidence from the Y chromosome

Cornelia Di Gaetano et al.

Abstract

The presence or absence of genetic heterogeneity in Sicily has long been debated. Through the analysis of the variation of Y-chromosome lineages, using the combination of haplogroups and short tandem repeats from several areas of Sicily, we show that traces of genetic flows occurred in the island, due to ancient Greek colonization and to northern African contributions, are still visible on the basis of the distribution of some lineages. The genetic contribution of Greek chromosomes to the Sicilian gene pool is estimated to be about 37% whereas the contribution of North African populations is estimated to be around 6%.

In particular, the presence of a modal haplotype coming from the southern Balkan Peninsula and of its one-step derivates associated to E3b1a2-V13, supports a common genetic heritage between Sicilians and Greeks. The estimate of Time to Most Recent Common Ancestor is about 2380 years before present, which broadly agrees with the archaeological traces of the Greek classic era. The Eastern and Western part of Sicily appear to be significantly different by the chi2-analysis, although the extent of such differentiation is not very high according to an analysis of molecular variance. The presence of a high number of different haplogroups in the island makes its gene diversity to reach about 0.9. The general heterogeneous composition of haplogroups in our Sicilian data is similar to the patterns observed in other major islands of the Mediterranean, reflecting the complex histories of settlements in Sicily.

Sickle cell disease in Sicily.

Roth EF Jr, Schiliro G, Russo A, Musumeci S, Rachmilewitz E, Neske V, Nagel R.

The chemical and physical properties of haemoglobin S derived from homozygotes for this haemoglobin in Sicily were examined, as well as some erythrocytic characteristics. Sicilian Hb S was identical to that found in USA black patients in electrophoretic mobility on both starch and citrate agar media, solubility, mechanical precipitation rate of oxyhaemoglobins, and minimum gelling concentration, as well as by peptide mapping and amino-acid analysis of all beta-chain peptides. Taken together with the presence in Sicily of African blood group markers and certain historical considerations, it seems clear that the source of Hb S in Sicily is Africa.While the clinical severity in nine Sicilian children did not seem remarkably different from the disease in the USA, the most severe and fatal complications were not seen. Mean Hb F Was 10.5% and 2,3-diphosphoglycerate (2,3-DPG) values were higher in Sicilian homozygotes than in black USA counterparts (21.79 mumol/g Hb vs 15.16). Red cell AT values were also slightly higher in Sicilian patients. The presence of concomitant thalassaemia was excluded by both family studies and globin chain synthetic ratios. In conclusion, haemoglobin S in Sicilian homozygotes is identical to Hb S found in USA blacks. Although the severity of the disease seems quite similar in both groups of patients, other erythrocytic properties were found to be different. Whether these factors influence severity remains to be elucidated

4 responses to “Sickle cell and Y DNA in Sicily

  1. I think that haplogroup E accounts for more than 5% of Sicilians. Semino found E3b at 10-27% in Italy.

  2. Probably.

  3. USA blacks are a hybrid people not real Africans. Why use knockoff Africans instead of the real thing?
    There are only a few non medical ways humans have managed to deal with Malaria: the sickle gene, thalassemia and GP6D deficiency. That is why you can find the same natural selection adaptations to Malaria in various places where that disease is common or was common as in Sardinia, Sicily, India, parts of Southeast Asia and of course Africa.

    You should know that in Africans, the real black ones, not knockoffs, many Africans die due to Malaria every year especially children. Those poor souls don’t have HbS or any other protection against that deadly disease. HbS is not 100% present in Africans in areas infested by Malaria.

    Instead of worrying about the whiteness of certain olive skinned Europeans try to improve the health status of Africans especially children affected by malaria.

    • The whiteness of Southern Europeans.. doesn’t bother me much. But this is an anthropology blog, not a medical one.

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