Each year a number of children are born with biological defects that impair normal function. 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 disorder inherited as a recessive allele is Tay-Sachs disease. This is caused by a dysfunctional enzyme that fails to break down brain lipids of a certain class. The symptoms usually become manifest a few months after birth. Some symptoms are seizures, blindness and degeneration of motor and mental performance. Death is the result of this disease, in children. With Tay-Sachs disease, the brain cells of a baby are unable ...view middle of the document...
Sickling of the cells, in turn, can lead to other symptoms. The multiple effects of a double dose 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 ward off brain damage in children with sickle-cell disease. Heterozygotes with the sickle-cell allele may suffer 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 abnormal hemoglobins are made. Only individuals who are homozygous for the sickle-cell allele suffer from the disease.Down syndrome is an aneuploid condition, meaning that if either of the aberrant gametes unites with a normal one at fertilization, the offspring will have an abnormal chromosome number. Down syndrome is usually the result of an extra chromosome, so that each body cell has a total of 47 chromosomes. In chromosomal terms, the cells are trisomic for chromosome 21. Its trisomy severely alters the individual's phenotype. Down syndrome includes characteristic facial features, short stature, he...
