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Sickle Cell Anemia

Daughter with SD Disease



My daughter is 2 years old and was diagnosed with SD disease. Can you please tell me what the complications are with this disease?


Hemoglobin SD disease is an inherited disorder that affects the red blood cells - the cells of the blood that carry oxygen. The part of the red blood cell that carries the oxygen is called hemoglobin. There are different types of hemoglobin - most people of hemoglobin A. Some other types of hemoglobin include D, E and S. They are due to changes called mutations in the HBB gene - the gene that codes for hemoglobin.

When someone has 2 copies of Hemoglobin S (SS) it causes sickle cell anemia. When someone has 1 copy of S and 1 copy of hemoglobin D - it can cause a similar disease called SD disease. Hemoglobin S can change the shape of red blood cells into a sickle (crescent) shape and Hemoglobin D prevents red blood cells from carrying oxygen effectively. Problems seen in SD disease can vary from mild anemia to more serious problems such as frequent episodes of pain, infection and organ damage.

SD disease is inherited in an autosomal recessive fashion. If a child has SD disease that means that one of the parents has a copy of hemoglobin S and the other parent has a copy of hemoglobin D. Someone who has one normal gene and one gene that codes for hemoglobin S or hemoglobin D is called a carrier. They do not have any health problems. But when they have children there is a one in four or 25% chance the child will get the two genes which make hemoglobin S and hemoglobin D and that child will then have SD disease.

This is an important question. I would recommend that you talk to your daughter's doctor about these issues. Hematologists are specialists that often take care of people with SD disease. You may also want to talk about the inheritance of SD disease with a genetic counselor or geneticist. The National Society of Genetic Counselors website has a resource for locating a genetics center near you.

Related Resources:

Genetic Counseling Resources

For more information:


Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University