By Carol Guzman
Every year, on the 19th of June, we celebrate World Sickle Cell Day to help raise awareness of the most commonly inherited blood disorders. You have probably heard about sickle cell disease when learning about genetics in your high school biology class, but have you heard of the ‘Jewish’ blood disorder, beta thalassemia? Both diseases affect hemoglobin production, result from mutations on the same gene, and can be passed down without any known family history.
Red blood cells carry oxygen from your lungs to other parts of your body using a protein called hemoglobin. Red blood cells are typically round and smooth and can easily glide through blood vessels and deliver oxygen throughout the body. Sickle cell diseases are a group of disorders that are caused by mutations in the hemoglobin – subunit beta (HBB) gene. A specific HBB mutation causes hemoglobin molecules to become abnormal, which leads the body’s red blood cells to stiffen and sickle. The hardened and sickled red blood cells easily pile up on one another, causing blockages in blood vessels, damage to vital organs, and the inability to deliver oxygen to bodily tissues.
In the United States, sickle cell disease is most prevalent among African Americans. Currently, the only cure for sickle cell disease involves a bone marrow/stem cell transplant. However, many clinical trials are working to create a less dangerous cure for the most common genetic disease.
Another specific HBB mutation causes a disease known as beta thalassemia. Rather than having abnormal hemoglobin that causes red blood cells to sickle, people with beta thalassemia do not make enough hemoglobin, resulting in a shortage of mature red blood cells and lack of oxygen.
Health professionals recommend Sephardic Jews get screening for beta thalassemia, as it often occurs in people of Mediterranean, North African and Middle Eastern countries.
Although the diseases result from different HBB mutations, they are typically inherited in an autosomal recessive pattern. Both parents need to be carriers of beta thalassemia or sickle cell disease in order to have a 25% risk of passing the disease down to each of their children and a 50% risk of each child becoming a carrier for either disease. A small number of cases have shown that beta thalassemia can also be inherited in an autosomal dominant manner, causing the disease to manifest in someone with just one beta thalassemia HBB gene mutation.
A newborn screening test can detect various kinds of mutations on the HBB gene, including the specific mutations for sickle cell disease or beta thalassemia. A doctor can also conduct a blood test on a newborn to check for sickle cells or low amounts of red blood cells.
Both sickle cell disease and beta thalassemia affect people worldwide. In Illinois, doctors screen all newborns for sickle cell disease and beta thalassemia. Talk to your doctor or a genetic counselor about adding beta thalassemia to your preconception carrier screening panel if you have Mediterranean, North African or Middle Eastern ancestry.
To learn more about the Sarnoff Center’s affordable, accessible carrier screening program or to speak with a genetic counselor, visit JewishGenetics.org/cjg/get-screened or contact us at GeneticScreening@juf.org.