Discovery
Although it has been around for thousands of years, mostly in the African continent, where it is believed that the first case of sickle-cell anemia originated around 7 thousand years ago, sickle-cell anemia is a relatively new concept in the west. Sickle cell anemia was 'discovered' by James Bryan Herrick in 1910, when Walter Clement Noel, a 20-year-old dental student from Grenada studying in Chicago, came to Dr. Herrick complaining of pain episodes, and symptoms of anemia. Herrick, a cardiologist by trade, handed off Noel's case to a resident, Dr. Ernest Irons. When Irons examined Noel's blood, he found the characteristics sickle-shaped blood cells that we have now come to associate with sickle-cell anemia. When Irons communicated this to Herrick, he became interested in finding out what type of new disease this might be. Herrick then published a paper on this condition in a medical journal. In 1917, Dr. V. Emmel suggested a genetic basis for the disorder, after studying the 3rd case of sickle cell anemia, which was discovered in 1915, by Cook and Meyer.
Nature of the disease
In 1927, Nicholas Hahn and Elizabeth Gillespie performed experiments using the 'ghosts' of burst blood cells to prove that the sickling phenomenon was caused by a factor in the hemoglobin. Later, in 1949, two scientists, Col. E. A. Beet, and Dr. James V. Neel. independently proved that the disease was genetically inherited. Additionally, they proved that those with a heterozygous genotype carried the condition, while those with a homozygous genotype have the condition. Despite this, the gene that caused this disease was still unknown. In 1951, Linus Pauling and Andrew Itano discovered that people with SCD (sickle-cell disorder, as it was then named) had a different structure in their hemoglobin, the reddish protein that allows red blood cells to carry oxygen. They determined that the HbS allele caused abnormal hemoglobin, and that the HbA allele caused normal hemoglobin. Pauling coined the term 'molecular disease' to describe such ailments caused by abnormalities in chemical structure. SCD was the first molecular disease to be discovered. Scientists Perutz and Mitchson later examined the solubility of the abnormal hemoglobin, and observed spindle-shaped liquid crystals. Pauling concluded that these rods caused the cell to sickle. Later, mapping of both the HbS and HbA genes demonstrated that the only difference between the two is one nucleotide base pair, located in the 6th codon of the beta-globin gene, which causes the RNA sequence GAG to be changed to GUG, like this:
