Sickle cell disease: no longer a single gene disorder

Patients who are homozygous for the sickle hemoglobin mutation can present with remarkably different clinical courses, varying from death in childhood, to recurrent painful vasoocclusive crises and multiple organ damage in adults, to being relatively well even until old age. Increasing numbers of genetic loci have now been identified that can modulate sickle cell disease phenotype, from nucleotide motifs within the beta-globin gene cluster, to …