An unexpectedly high frequency of heterozygosity for alpha-thalassemia in Ashkenazi Jews

Haplotype analysis of α-thalassemia chromosomes reveals heterogeneity and multiple founders in Ashkenazi Jews

α-Thalassemia (α-thal) is among the world's most common single gene disorders, generally attributed to a selective advantage of heterozygotes against malaria mortality. A high frequency of -α^3.7 deletion heterozygosity has been previously reported in Ashkenazi Jews despite lack of obvious malarial selection pressure in this population. Using haplotype and -α^3.7 subtype analysis we analyzed a subset of -α^3.7 homozygotes from various Israeli ethnic groups. We found a high frequency of the common Ia haplotype in Yemenite Jews and Arabs (54% and 13% respectively). Ashkenazi Jews exhibited a high frequency of IIIb alleles (67%) previously reported only in Aboriginal Australians and not found in other Israeli ethnicities. Both Yemenites and Ashkenazim carried the rare IIh alleles (18% and 15% respectively). These results may suggest multiple founder effects in Ashkenazi Jews as well a common founder for both Yemenite and Ashkenazi Jews.

Ashkenazi Jews and breast cancer: the consequences of linking ethnic identity to genetic disease

We explored the advantages and disadvantages of using ethnic categories in genetic research. With the discovery that certain breast cancer gene mutations appeared to be more prevalent in Ashkenazi Jews, breast cancer researchers moved their focus from high-risk families to ethnicity. The concept of Ashkenazi Jews as genetically unique, a legacy of Tay-Sachs disease research and a particular reading of history, shaped this new approach even as methodological imprecision and new genetic and historical research challenged it. Our findings cast doubt on the accuracy and desirability of linking ethnic groups to genetic disease. Such linkages exaggerate genetic differences among ethnic groups and lead to unequal access to testing and therapy.