BIOS 256 Week 7 Case Study; Understanding Cystic Fibrosis Genetics

BIOS256- Week 7 Case Study: Cystic Fibrosis Genetics refers to the study of heredity, specifically which genes are passed on from each parent, and which genes are active. Our nuclear DNA is a combination of DNA from both the paternal and maternal parent, and the genes associated with this DNA can lead to a variety of traits. The term genotype refers to the actual combination of alleles, whereas the phenotype would be how the trait is being expressed. For most of the genes that will generate our physical characteristics, they will be two forms, the dominant form, and the recessive form. A dominant allele (gene) is one that will be expressed if there is at least one copy of the gene. For example, one or both parents could give a copy of this gene, and the expression pattern would be the same. A recessive allele is one that can only be expressed in the absence of a dominant gene, and typically, both copies of the gene must be recessive. In the case of complete dominance inheritance, if either of the genes is the dominant form, then the phenotype would be the dominant trait. If all the genes are in the recessive form, or there is no dominant allele, then the phenotype would be the recessive trait. When discussing genetic disorders associated with any genes on chromosomes 1 – 22, we refer to them as autosomal conditions. Autosomal dominant disorders are those that will occur if either parent gives the offspring the dominant gene. Examples of this would include Marfan’s syndrome, familial hypercholesterolemia, and hereditary long QT syndrome. Autosomal recessive disorders require both parents to give the offspring a copy of the recessive gene, regardless of if the parent expresses the dominant phenotype due to having another copy of the gene that is dominant. Examples of this would include sickle cell disease, cystic fibrosis, and Tay-Sachs disease. The parents in the case of an autosomal recessive disorder may be considered carriers if they have both a copy of the dominant gene and a copy of the recessive gene. Individuals with autosomal recessive disorders will pass on that recessive gene if they do produce offspring. Cystic fibrosis is a genetic condition that predominantly affects Caucasian individuals. This condition affects the cellular membranes in the lungs and digestive systems, leading to a buildup of fluids such as mucus, sweat, and digestive juices. These fluids become viscous (thick) that can lead