Multiple systems for diagnosis of sickle cell disease. Laser coagulation has been used in people with retinopathy caused by sickle cell disease. Robby suffers from intermittent bouts of sickle cell crisis. There are different forms of sickle cell disease. Stargell also worked to raise awareness of sickle cell anemia. One trial focused on analyzing bone marrow sample from patients with sickle cell anemia. However, individuals with sickle cell trait may have rare complications. HbS. This makes the individual heterozygous for sickle cell. Similarly, it is limited in distinguishing bone infarcts from osteomyelitis in sickle cell anemia. Clinical trials of gene therapy for sickle cell disease were started in 2014. Signs of sickle cell disease usually begin in early childhood. Three-quarters of sickle cell cases occur in Africa. In 1954, the protective effect against malaria of sickle cell trait was described. The discovery that hemoglobin F alleviated the symptoms of sickle cell disease occurred in 1948. Her brother Sean died in 1990 of sickle cell anaemia aged 27.