Pathophysiology and perioperative management of sickle cell disease

Orthopaedic Manifestations of Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive disorder that results in hemolytic anemia related to abnormal hemoglobin and erythrocyte levels. SCD is characterized by vascular occlusive episodes, visceral sequestration, and aplastic or hemolytic crises. These crises most commonly occur in bone. The orthopaedic manifestations of SCD comprise much of the morbidity associated with this disorder. Osteonecrosis and osteomyelitis are among the most disabling and serious musculoskeletal complications in patients with SCD. Effective management of the bone and joint sequelae requires an accurate diagnosis, an understanding of the pathophysiology of the disease, and knowledge of available medical and surgical treatment alternatives. The major orthopaedic manifestations of SCD are osteonecrosis, osteomyelitis, septic arthritis, and bone infarction. Patients with SCD require close monitoring in the perioperative period because of the risk for vasoocclusive crisis.

Perinatal and Neonatal Implications of Sickle Cell Disease

Sickle cell disease is the genetic disorder most commonly detected with state-mandated newborn screening. Women with sickle cell disease struggle with psychosocial, emotional, and physical challenges throughout their lives. Pregnancy for women with sickle cell disease brings greater risk for maternal and fetal morbidity and mortality and increased likelihood of hospitalization for complications, including sickle cell pain crisis. Chronic maternal opioid use for pain can place newborns at risk for neonatal abstinence syndrome. Care of a pregnant woman with sickle cell disease requires a collaborative, multidisciplinary team addressing the medical, social, and emotional needs of the woman and her family.

Use of genome-editing tools to treat sickle cell disease

Recent advances in genome-editing techniques have made it possible to modify any desired DNA sequence by employing programmable nucleases. These next-generation genome-modifying tools are the ideal candidates for therapeutic applications, especially for the treatment of genetic disorders like sickle cell disease (SCD). SCD is an inheritable monogenic disorder which is caused by a point mutation in the β-globin gene. Substantial success has been achieved in the development of supportive therapeutic strategies for SCD, but unfortunately there is still a lack of long-term universal cure. The only existing curative treatment is based on allogeneic stem cell transplantation from healthy donors; however, this treatment is applicable to a limited number of patients only. Hence, a universally applicable therapy is highly desirable. In this review, we will discuss the three programmable nucleases that are commonly used for genome-editing purposes: zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9). We will continue by exemplifying uses of these methods to correct the sickle cell mutation. Additionally, we will present induction of fetal globin expression as an alternative approach to cure sickle cell disease. We will conclude by comparing the three methods and explaining the concerns about their use in therapy.