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Picrel: distribution of the sickle cell trait, shown in pink and purple. Sickle cell gene mutation probably arose spontaneously in different geographic areas,[56] as suggested by restriction endonuclease analysis. These variants are known as Cameroon, Senegal, Benin, Bantu, and Saudi-Asian. Their clinical importance is because some are associated with higher HbF levels, e.g., Senegal and Saudi-Asian variants, and tend to have milder disease.
https://en.wikipedia.org/wiki/Sickle_cell_disease