Genetic Disorders :: essays research papers

individually year a number of children are born with biologic defects that featherbed normal social occasion. For THREE of the following conditions, discuss such aspects as the biological cause, the methods of treatment and possible means of detection and/or prevention.One lethal rowdyism inherited as a recessive allele is Tay-Sachs disease. This is caused by a dys running(a) enzyme that fails to break down brain lipids of a certain class. The symptoms usually become manifest a few months after birth. or so symptoms are seizures, blindness and degeneration of motor and mental performance. Death is the precede of this disease, in children. With Tay-Sachs disease, the brain cells of a baby are unable(p) to metabolize gangliosides, a type of lipid, because a crucial enzyme does not process properly. As the lipids accumulate in the brain, the brain cells gradually cease to function normally. Only children who inherit dickens copies of the Tay-Sachs allele qualifies as a reces sive. At the biochemical level, we observe an intermediate phenotype characteristic of incomplete ascendence The enzyme deficiency that causes Tay Sachs disease quite a little be detected in heterozygotes, who cod an activity level of the lipid-metabolizing enzyme that is intermediate between individuals homozygous for the normal allele and individuals with Tay-Sachs disease. Heterozygotes lack symptoms of the disease, apparently because half the normal amount of functional enzyme is sufficient to prevent lipid accumulation in the brain. In fact, heterozygous individuals produce equal numbers of normal and dysfunctional enzyme molecules. At the molecular(a) level, the normal allele and the Tay-Sachs allele are codominant. Sickle-cell disease is caused by the substitution of a single amino acid in the hemoglobin protein of red blood cells. When the oxygen content of an affected individuals blood is low, the sickle-cell hemoglobin deforms the red cells to a sickle shape. Sickling o f the cells, in turn, can lead to other symptoms. The multiple effects of a double paneling of the sickle-cell allele exemplify pleiotropy, which is the ability of a gene to affect an organism in many ways. Regular blood transfusions could be used to harbor off brain damage in children with sickle-cell disease. Heterozygotes with the sickle-cell allele may can some symptoms of the disease when there is a reduction of blood oxygen. Since the two alleles are codominant at the molecular level both normal and aberrant hemoglobins are made. Only individuals who are homozygous for the sickle-cell allele suffer from the disease.