Sickle cell disease is a hereditary disorder caused by a mutation that produces hemoglobin S or HbS (which is different from normal hemoglobin HbA). HbS changes the shape and consistency of red blood cells, which tend to polymerize in low-oxygen environments (1). This disease is most serious in individuals who inherit S genes from both parents (homozygous SS sickle cell disease), meaning that the mutation is present on both chromosomes (Figure 1).
It is important to distinguish between the “S trait” and sickle cell disease. Carriers of the sickle cell trait inherit one gene that codes for HbS from one parent, and one gene that codes for HbA from the other, so they do not display any symptoms. HbS provides some relative protection against life-threatening complications from malaria, which explains its historic distribution. This mutation appeared independently in Africa and India and is most common among populations from these regions. The African slave trade and historic migration patterns, however, have also led to the disease being common in America, the Caribbean, Brazil, the Mediterranean Region, and the Middle East. More contemporary migration patterns have disrupted this distribution, making the issue a global concern. It is estimated that there are 5 million healthy carriers born every year, along with roughly 300,000 homozygous SS babies. This makes sickle cell disease the most common genetic disorder both in the world and in France (2).
There is a lack of reliable epidemiological data about sickle cell disease in France…