Genetic Disorders Essay Example

to affect an organism in multiple ways, is exemplified by the multiple effects observed when an individual possesses two copies of the sickle-cell allele. Regular blood transfusions are used for children with sickle-cell disease to prevent brain damage. Heterozygotes carrying the sickle-cell allele may experience certain symptoms if there are reduced blood oxygen levels. At a molecular level, both normal and abnormal hemoglobins are produced because the two alleles exhibit codominance. Only individuals who have two copies of the sickle-cell allele will experience this disease. Down syndrome occurs when fertilization involves one abnormal gamete and one normal gamete, resulting in offspring with an abnormal chromosome number due to extra chromosomes being present. Each body cell contains 47 chromosomes, making it trisomic for chromosome 21. Down syndrome causes significant changes in phenotype, including distinctive facial features, short stature, heart problems, susceptibility to respiratory infections, and intellectual disability.The majority of cases of Down syndrome are caused by errors during gamete production in one parent, known as nondisjunction. Nondisjunction can occur when chromosomes do not separate correctly in either meiosis I or meiosis II. This results in one gamete having two copies of a chromosome type, while another gamete has none. Advanced maternal age is associated with an increased risk of carrying a trisomic embryo to term instead of experiencing spontaneous abortion. Amniocentesis is a diagnostic procedure that can be used to detect Down syndrome by analyzing cells from the amniotic fluid collected during pregnancy. Chorionic villus sampling provides faster results within 24 hours and involves removing a small amount of fetal tissue from the placenta.