SI-158, 164, 213, 223, 233, 254, 277, 405, 418, 420: (HBB) Hemoglobin Beta Locus
• Cell line states:
o SI-158: carrier (N/IVS 1-1)
o SI-164: affected (cd39/IVS1-110)
o SI-213: carrier (N/IVS1-110)
o SI-223: affected (IVSI-6/IVSI-6)
o SI-233: affected (HbS/HbS – sickle cell anemia)
o SI-254, 277: affected (Unknown/IVSII-1)
o SI-405: affected (IVS1-5/Cd8+G)
o SI-418: affected (cd8+G/619del)
o SI-420: affected (cd8+G/FA)
• Defects in HBB are the cause of sickle cell Sickle cell anemia, characterized by abnormally shaped red cells resulting in chronic anemia and periodic episodes of pain, serious infections and damage to vital organs. Normal red blood cells are round and flexible and flow easily through blood vessels, but in sickle cell anemia, the abnormal hemoglobin (called Hb S) causes red blood cells to become stiff. They are C-shaped and resembles a sickle. These stiffer red blood cells can lead to microvascular occlusion thus cutting off the blood supply to nearby tissues.
• Defects in HBB are the cause of beta-thalassemia. The thalassemias are the most common monogenic diseases and occur mostly in Mediterranean and Southeast Asian populations. The hallmark of beta-thalassemia is an imbalance in globin-chain production in the adult HbA molecule. Absence of beta chain causes beta(0)-thalassemia, while reduced amounts of detectable beta globin causes beta(+)-thalassemia. In the severe forms of beta-thalassemia, the excess alpha globin chains accumulate in the developing erythroid precursors in the marrow. Their deposition leads to a vast increase in erythroid apoptosis that in turn causes ineffective erythropoiesis and severe microcytic hypochromic anemia.