An inherited and chronic red blood cell disorder that can cause pain, damage in blood vessels and low blood count. It is said that 8/100 African Americans are carriers if the disease, even though they do not live in malarial areas. Also found in the eastern Mediterranean, parts of the Gulf, and in northeastern India. It is characterised by distortion of the red blood cells, which are quickly lost to circulation, often resulting in anemia. It is due to homozygosity for allele HbS, producing a single amino substitution in the (-chain of the normal haemoglobin molecule determined by allele HbA. Individuals heterozygous for the allele HbAHS are resistant to the most serious form of malaria, and allele Hbs achieves a high frequency in malarial areas
. See Anemia