SICKLE CELL ANAEMIA: AN INTRODUCTION by Ebele Iloabachie; Embryologist at Medical ART Center
Sickle cell anaemia is a genetic disorder affecting millions and according to the president of “The sickle cell aid foundation” Abuja, Nigeria has the largest number of people affected by sickle cell in the world. (https://www.thecable.ng/advocate-nigeria-highest-rate-sickle-cell-anaemia-world-no-money-cure)
Haemoglobin is a very important protein molecule found in red blood cells with the main function of transporting oxygen from the lungs to all body tissues. Sickle cell anemia results in an abnormality of this protein. Healthy red blood cells that contain normal haemoglobin are disc shaped (round) and flexible enabling easy movement through large and small blood vessels to deliver oxygen. With sickle cell, haemoglobin can form stiff rods within the red cells making them have crescent or sickle shapes. These sickle shaped red blood cells are rigid and may stick to the walls of vessels thereby causing blockage that restricts the flow of blood. If there is no blood flow, oxygen cannot reach nearby tissues. Lack of oxygen in tissues may lead to recurring and severe pain attacks called “crises’’. These attacks can occur without warning and may require hospital treatment. As it is a life-long illness, sickle cell anaemia can lead to organ damage in an individual as well as early death.
Sickle cell anaemia is hereditary, meaning that the disease is inherited or can be passed down by genes from parents to their children. People affected by this disease have abnormal haemoglobin S (Hb S) or sickle haemoglobin instead of normal haemoglobin A in their red blood cells. When a person inherits two hemoglobin S genes (Hemoglobin SS) from each parent, he or she will be affected.
SICKLE CELL ANAEMIA: PREVENTION WITH THE HELP OF PRE-IMPLANTATION GENETIC TESTING (PGT)
Sickle cell anaemia is a hereditary blood disorder which initially was not preventable and lasts a life time. The only known cure is a bone marrow transplant, otherwise treatment focuses on symptom management. Couples (carriers of the trait/gene) who are planning to start a family have a 25% chance of having a child affected by this disorder. With the advent of a new technology in the early 90’s, couples at risk of passing down this disorder now have good reason to smile as it is possible to have children without sickle cell anaemia
Pre implantation genetic testing can be described as the genetic profiling of embryos before implantation. Thus it is always used in conjunction with assisted reproductive technology and requires IVF for the production of embryos to be analyzed. When used to screen for specific genetic diseases (e.g. sickle cell anaemia), this method helps to prevent selective pregnancy termination, by significantly decreasing the chances of having an affected child (i.e. with this method, it is very likely that the baby will be free of the disease in question). Medical Art Center (MART) is one of the few clinics in Nigeria that offer PGD as a treatment option.
It is important to note that although PGT tested embryos have recorded great success resulting in pregnancies and live birth of disease free infants, the only gold standard technique to accurately determine the presence or absence of sickle cell in a pregnancy is “Pre-natal Diagnosis” which may be done by amniocentesis, chorionic villi sampling and fetal blood sampling. Women at risk of having a baby with a genetically inherited disease of haemoglobin are advised to discuss these available options before becoming pregnant.