Each cell in the human body contains about 25,000 to 35,000 genes, which carry deoxyribose nucleic acid, or DNA, which determines each characteristic a person will possess, according to the Nemours Foundation. Damage to the DNA causes the gene to mutate, or change, which can lead to disease. Genetic diseases are present at birth and passed down from parent to child, and can affect many different functional systems of the body.
Lung Diseases
Cystic fibrosis, a genetic disease which affects nearly 30,000 people in the United States, according to the Cystic Fibrosis Foundation, causes the production of excessive mucus. This mucus clogs the lungs and pancreas, making breathing difficult, interfering with the exchange of oxygen, and attracting bacteria to the lungs, leading to infection.
A defect in the gene which codes for the protein known as alpha-1 antitrypsin causes the disease alpha-1 antitrypsin deficiency. Alpha-1 antitrypsin protects the lungs from neutrophil elastase, an enzyme which damages the lungs when too much is present, as described by the Alpha-1 Association.
Heart Diseases
Genetic diseases also affect the heart leading to defects in the formation of the heart or the valves in the heart. Hypertrophic cardiomyopathy, one example of a genetic heart disease, causes the heart muscle to enlarge, interfering with its ability to pump blood. Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in those under the age of 30, according to the Cleveland Clinic.
Metabolic Diseases
Metabolic diseases are those which interfere with the body's ability to process food into energy. Although many different metabolic diseases can occur, the most common is type 1 diabetes, also known as insulin-dependent diabetes. Type 1 diabetes is a "complex trait", according to the U.S. National Library of Medicine and National Institutes of Health, meaning that it requires mutations in many different genes for the disease to occur. Type 1 diabetes affects approximately 16 million Americans.
Other genetic metabolic diseases include phenylketonuria and adrenoleukodystrophy. Those with phenylketonuria cannot produce the enzyme phenylalanine hydroxylase which is necessary to convert the amino acid phenylalanine into tyrosine. This leads to a buildup of phenylalanine, which is toxic to the body and results in mental retardation and damage to the organs. Adrenoleukodystrophy causes the adrenal gland to degenerate, leading to neurological disability and even death.
X-Linked Diseases
Diseases which affect genes carried by the X sex chromosome are known as X-linked diseases. X-linked diseases may either be dominant, which affect both girls and boys, or recessive, which affect only boys.
Dominant X-linked diseases cause conditions ranging from mild skin abnormalities to severe diseases. Albright's hereditary osteodystrophy causes mental retardation, seizures and inhibited growth. Goltz syndrome results in mental retardation. Cylindromatosis is a condition characterized by deafness and tumor formation in the upper body. Incontinentia pigmenti results in abnormal swirls in the pigmentation of the skin.
Recessive X-linked genetic diseases are often life-threatening conditions passed on from mother to son. Severe combined immunodeficiency syndrome causes a defect in the immune system, leading to serious and often fatal infections. Hemophilia affects the clotting factors in the body, increasing the risk of severe bleeding. Duchenne muscular dystrophy affects the muscles, leading to muscle wasting and resulting in death usually by the age of 30, according to the Muscular Dystrophy Association.
