Each cell within the human body contains thousands of genes, which collectively make up the genome. Specific sequences of chemicals called nucleotide bases link together to form long stretches of deoxyribonucleic acid, or DNA, called chromosomes. Most cells within the body contain two sets of 23 chromosomes, thousands of genes and billions of nucleotide bases.
Inherited diseases develop when parents with genetic mutations pass those mutations on to their children, leading to cellular dysfunction that ultimately causes disease. There are a number of inherited diseases, some of which can prove fatal.
Hemochromatosis
The most common inherited disorder in the United States is hemochromatosis, reports the University of Maryland Medical Center. Hemochromatosis is a metabolic disorder characterized by increased absorption of iron by tissues throughout the body. Normally, iron is localized within specific tissues, such as red blood cells, where iron helps make up hemoglobin. In hemochromatosis, other tissues accumulate iron, leading to iron toxicity. The disease leads to lethargy, depression and joint pain and can eventually lead to heart failure or diabetes.
Hemochromatosis is caused by mutations to a gene called HFE. It is an autosomal recessive disorder, which means that a child must inherit a mutant HFE gene from both parents in order to develop the disease. The University of Maryland Medical Center indicates that around one in 10 people carry the mutation for hemochromatosis. If both parents carry the mutation, there is a one in four chance their child will develop the disease.
Huntington Disease
Huntington's is an inherited genetic disease that affects the central nervous system. The disease typically develops in adults between the ages of 30 to 40, though it may develop earlier or later in life. Patients with Huntington's experience progressive loss of muscle control and motor functioning, as well as dementia, memory loss and personality changes.
Mutations to regions of chromosome 4 within the genome lead to Huntington's disease. Huntington's is an autosomal dominant disorder, which means that a child needs only to inherit one mutant copy of the gene in order to develop the disease, reports the University of Kansas Medical Center. If one parent has Huntington's disease, there is a 25 percent chance of the child inheriting the disease, and if both parents have Huntington's, their children have a 75 to 100 percent chance of getting the disease. Genetic screening for Huntington's can identify the disease before the onset of symptoms.
Hemophilia
Hemophilia is an inherited bleeding disorder characterized by uncontrolled hemorrhaging following injury. Under normal conditions, injury to blood vessels stimulates the formation of clots, made up of cells called platelets, which block the site of injury and stop the bleeding. Patients with hemophilia cannot form clots, so they continue to bleed for extended periods following injury.
The Genetics Home Reference indicates that hemophilia is caused by mutations to the genes F8 or F9, leading to mutation or inactivation of coagulation factor proteins. Hemophilia is an X-linked disorder, which means the disease is associated with mutations to the X chromosome. Since males have only one X chromosome, whereas females have two and, therefore, require two mutant gene copies, hemophilia is more common in males than females. Treatment for hemophilia involves supplementing the levels of clotting factors in the blood to prevent uncontrolled bleeding.
