Sickle Cell Anemia
Sickle cell anemia research papers examine the disease that is an inherited blood disorder. Medical health writers research the disease and give the most recent information in a custom written paper.
Sickle cell anemia, (SCA) one of the three distinct types of sickle cell disease, is the most common inherited blood disorder in the United States. The disease affects the following:
- About 1 of 500 African Americans
- 2,000 neonates a year
- About 72,000 people, most of whom have sub-Saharan African ancestry, although people with Indian subcontinent, Central and South American regions, Mediterranean (Turkey, Greece, Italy) and Caribbean heritage also frequently inherit SCA.
Most children with SCA do not exhibit symptoms until their fetal hemoglobin levels fall and postnatal hemoglobin increases, but before their first year functional asplenia usually develops and they may die from septicemia or other complications unless SCA is diagnosed first (OMIM, 2004) and is comprehensively treated in clinical and home settings, making maternity nursing caregiver knowledge of the disease important for neonatal health care. An overview of SCA will be described here.
Inheritance of Sickle Cell Anemia
Inheritance of the sickle cell hemoglobin gene is usually determined during prenatal testing or at birth, when screening tests, usually using isoelectric focusing or high-performance liquid chromatography (HPLC), are carried out, as mandated in 44 states . SCA's genetic autosomal recessive basis is well understood. The disease is the result of homozygous inheritance of a recessive gene mutation that causes substitution of glutamic acid for what would normally be valine at position six on the 146 amino acid beta globin (HbB) protein sequence in hemoglobin formation, as was demonstrated by V. Ingram in 1956. The conversion of the single amino acid causes a structurally defective sickle cell hemoglobin molecule (HbS) to form instead of normal hemoglobin. The oxygen transporting molecules in red blood cells are composed of two alpha and two beta polypeptide chains. The HbB gene that codes for the beta chain or beta globin, is located at the 15.5 region of chromosome 11 (OMIM, 2004). Other point mutations cause blood diseases such as beta thessalemia, but the mutated HbS gene causes sickle cells form in varying quantities unless the HbS is mitigated by the inheritance of a normal hemoglobin gene coding (HbA) from parental DNA. Heterozygous inheritance of an HgS gene from 11p15.5 creates carriers, who have the sickle cell trait (designated as HgAS) but are healthy and asymptomatic, while those with SCA, (designated as HgSS), inherited an HgS gene from each parent and express the disease phenotypically and genetically. When both parents are HgAS, there is a 25% chance, for each child, that it will be born with SCA, a 25% chance that it will be a non-carrier, and a 50% chance that it will be, like its parents, a trait carrier, since each parent may contribute either an unaffected or affected gene. When only one parent has the trait, there is an equal chance (50%) that each child will be a trait carrier or will have normal genes. Every child born to one parent with normal HbA and one with HbS will have the trait, while a child from one parent with SCA and one with the trait will be equally likely (50%) to have SCA or to only carry the trait and experience few or no symptoms.