Cystic Fibrosis
If both parents must have a point mutation in their CF genes in order to create a child with CF, how common do you think the disease is in the population?
CF is an autosomal recessive gene, meaning that both parents must pass on the mutated gene for it to be present. If one parent passes on a good gene and the other passes a bad one, the person will only be a carrier of the gene and the disease will not show up. If both parents are heterozygous with the CF gene, they have a 1 in 4 chance of having a baby with cystic fibrosis. Approximately 1 in 30 Caucasian Americans is a carrier of a cystic fibrosis mutation. Although CF is less common in these groups, approximately 1 in 46 Hispanics, 1 in 65 African and 1 in 90 Asians carry at least one abnormal CFTR gene. Approximately 30,000 Americans have CF, making it one of the most common life-shortening inherited diseases in the United States.
What other diseases are thought to be caused by point mutations? What do point mutations do in those diseases?
Sickle-cell disease is caused by a single point mutation in the beta-hemoglobin gene that converts a GAG codon into GUG, which encodes the amino acid valine rather than glutamic acid. Tay - Sachs disease is an autosomal recessive genetic disorder caused by a genetic defect in a single gene with one defective copy of that gene inherited from each parent. This disease occurs when harmful quantities of gangliosides accumulate in the nerve cells of the brain, eventually leading to the premature death of those cells.
Lister Hill National Center for Biomedical Communications. (2011, February 27). Tay - Sachs disease. Retrieved March 2, 2011, from
CF is an autosomal recessive gene, meaning that both parents must pass on the mutated gene for it to be present. If one parent passes on a good gene and the other passes a bad one, the person will only be a carrier of the gene and the disease will not show up. If both parents are heterozygous with the CF gene, they have a 1 in 4 chance of having a baby with cystic fibrosis. Approximately 1 in 30 Caucasian Americans is a carrier of a cystic fibrosis mutation. Although CF is less common in these groups, approximately 1 in 46 Hispanics, 1 in 65 African and 1 in 90 Asians carry at least one abnormal CFTR gene. Approximately 30,000 Americans have CF, making it one of the most common life-shortening inherited diseases in the United States.
What other diseases are thought to be caused by point mutations? What do point mutations do in those diseases?
Sickle-cell disease is caused by a single point mutation in the beta-hemoglobin gene that converts a GAG codon into GUG, which encodes the amino acid valine rather than glutamic acid. Tay - Sachs disease is an autosomal recessive genetic disorder caused by a genetic defect in a single gene with one defective copy of that gene inherited from each parent. This disease occurs when harmful quantities of gangliosides accumulate in the nerve cells of the brain, eventually leading to the premature death of those cells.
Lister Hill National Center for Biomedical Communications. (2011, February 27). Tay - Sachs disease. Retrieved March 2, 2011, from