Chromosome abnormalities usually occur when there is an error in cell division resulting in cells with too few or too many copies of a chromosome. Most chromosome abnormalities originate in the egg or sperm (gametes) but some happen during embryo development or are inherited from a parent.
Cystic fibrosis is an inherited disease characterized by the buildup of thick, sticky mucus that can damage many of the body's organs. The disorder's most common signs and symptoms include progressive damage to the respiratory system and chronic digestive system problems.
Hereditary hemochromatosis is a disorder that causes the body to absorb too much iron from the diet. The excess iron is stored in the body's tissues and organs, particularly the skin, heart, liver, pancreas, and joints.
Huntington disease is a progressive brain disorder that causes uncontrolled movements, emotional problems, and loss of thinking ability (cognition). Adult-onset Huntington disease, the most common form of this disorder, usually appears in a person's thirties or forties.
Marfan syndrome is a genetic disorder that affects the body’s connective tissue. Connective tissue holds all the body’s cells, organs and tissue together. It also plays an important role in helping the body grow and develop properly.
Sickle cell disease is a group of disorders that affects hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this disorder have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle, or crescent, shape.
For many single-gene disorders, the genetic basis is well understood, and the disease-causing gene variants can be identified with genetic testing. People are tested for two main reasons: to find out if they have a particular genetic disorder, or to find out if they are a carrier.