Genetic Disorders 

Learn about Genes, DNA, and Chromosomes

A genetic disorder is a disease caused by changes in DNA, also known as mutations. The change in DNA can be:

  1. A change (a mutation) in one gene

    1. Also known as: monogenic disorder, single-gene disorders, Mendelian inheritance disorder

    2. There are more than 10,000 known single-gene disorders

    3. Examples: sickle cell disease (HBB gene), cystic fibrosis (CFTR gene), Huntington disease (HTT gene)

  2. A combination of gene changes and environmental factors

    1. Also known as: multifactorial inheritance disorder

    2. There should be more than monogenic disorders in number

    3. Examples: Alzheimer's disease, arthritis, diabetes, obesity, heart disease and cancers

  3. Changes to chromosomes

    1. Also known as chromosome abnormalities

    2. The changes can be the number of chromosomes:

      1. Examples: Down syndrome, Klinefelter syndrome, or Turner syndrome

    3. The changes can be the structure of chromosomes

      1. Examples:

        Chromosomal translocation, such as Philadelphia translocation (9-22), also known as Chronic Myelogenous Leukemia (CML)

        Chromosomal deletions, such as 22q11.2 deletion syndrome (CATCH22)，or William's syndrome (del in 7)

Nearly all diseases have a genetic component. Some diseases are caused by mutations that are inherited from the parents and are present in an individual at birth, like sickle cell disease. Other diseases are caused by acquired mutations in a gene or group of genes that occur during a person's life. Such mutations are not inherited from a parent, but occur either randomly or due to some environmental exposure (such as cigarette smoke). These include many cancers, as well as some forms of neurofibromatosis.

 

Inherited disorder

An inherited disorder is caused by defective genes that can be passed down by parents to their children.

List of Genetic Disorders

This list of genetic, orphan and rare diseases is provided for informational purposes only and is by no means comprehensive.

Achondroplasia

Achondroplasia is a disorder of bone growth. It is the most common form of disproportionate short stature. It occurs in one in every 15,000 to one in 40,000 live births.

Alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is an inherited condition that causes low levels of, or no, alpha-1 antitrypsin (AAT) in the blood. Alpha-1 antitrypsin (AAT) is a protein that is made in the liver. The liver releases this protein into the bloodstream. AAT protects the lungs so they can work normally. Without enough AAT, the lungs can be damaged, and this damage may make breathing difficult.

Antiphospholipid syndrome (APS)

Antiphospholipid syndrome (APS), also known as antiphospholipid antibody syndrome and sometimes Hughes syndrome, is a disorder characterized by elevated levels of multiple different antibodies (proteins produced by the body to fight off foreign substances) that are associated with both arterial and venous thrombosis (clots in the arteries and veins).

Attention Deficit Hyperactivity Disorder (ADHD)

Attention Deficit Hyperactivity Disorder (ADHD) is a neurological disorder that affects a person's ability to control their behavior and pay attention to tasks.

Autism Spectrum Disorders (ASDs):

Autism - or more precisely the autism spectrum disorders (ASDs) - represent a broad group of developmental disorders characterized by impaired social interactions, problems with verbal and nonverbal communication, and repetitive behaviors or severely limited activities and interests.

Autosomal Dominant Polycystic Kidney Disease (PKD):

Autosomal Dominant Polycystic Kidney Disease (PKD) is a genetic disorder characterized by the growth of numerous cysts in both kidneys. The progressive expansion of PKD cysts slowly replaces much of the normal mass of the kidneys, and can reduce kidney function and lead to kidney failure.

 

Cancer: 

Charcot-Marie-Tooth disease (CMT):

Charcot-Marie-Tooth disease (CMT) is an inherited neurological disease characterized by a slowly progressive degeneration of the muscles in the foot, lower leg, hand, and forearm, and a mild loss of sensation in the limbs, fingers, and toes. 

Cri du chat syndrome:

Cri du chat syndrome is a rare genetic condition that is caused by the deletion of genetic material on the the p arm of chromosome 5.

Crohn's disease:

Crohn's disease is a chronic inflammatory disorder of the bowel, usually diagnosed in people between the ages of 20 – 30.

Cystic fibrosis (CF):

Cystic fibrosis (CF) is a fatal genetic disease. CF causes the body to produce thick, sticky mucus that clogs the lungs, leads to infection, and blocks the pancreas, which stops digestive enzymes from reaching the intestine where they are required in order to digest food.

Dercum disease:

Dercum disease - also known as Adiposis Dolorosa, Anders' syndrome and Dercum-Vitaut syndrome - is a rare condition that is characterized by multiple, painful fatty lipomas (benign, fatty tumors) that occur chiefly in post-menopausal, obese women of middle age. However, although it is 20 times more common in women, 16 percent of the reported cases are males and it can also occur in people who are not obese.

Down syndrome:

Down syndrome is a chromosomal condition related to chromosome 21. It affects 1 in 800 to 1 in 1000 live born infants.

Individuals with Down syndrome also have an increased risk for having heart defects, digestive problems such as gastroesophageal reflux or celiac disease, and hearing loss. Some people who have Down syndrome have low activity of the thyroid gland (hypothyroidism) - an organ in the lower neck that produces hormones.

Duane syndrome:

Duane syndrome is a rare, congenital eye movement disorder.

Duchenne muscular dystrophy (DMD):

Duchenne muscular dystrophy (DMD) is a rapidly progressive form of muscular dystrophy caused by a mutation in the DMD gene.

Factor V Leiden:

Factor V Leiden is the name of a specific mutation (genetic alteration) that results in thrombophilia, or an increased tendency to form abnormal blood clots in blood vessels. 

Familial hypercholesterolemia:

Familial hypercholesterolemia is an inherited condition that causes high levels of low density lipoprotein (LDL) cholesterol beginning at birth and heart attacks at an early age.

Familial Mediterranean Fever (FMF):

Familial Mediterranean Fever (FMF) is an inherited disease, characterized by recurrent attacks of fever, inflammation of the abdominal lining (peritonitis), inflammation of the lining surrounding the lungs , painful, swollen joints, and a characteristic ankle rash.

Fragile X syndrome:
Fragile X syndrome is the most common form of inherited intellectual disability in males and is also a significant cause of intellectual disability in females.

Gaucher disease:

Gaucher disease is an autosomal recessive inherited disorder of metabolism where a type of fat (lipid) called glucocerebroside cannot be adequately degraded. People who have Gaucher disease do not make enough glucocerbrosidase. This causes the specific lipid to build up in the liver, spleen, bone marrow and nervous system interfering with normal functioning.

Hereditary hemochromatosis:

Hereditary hemochromatosis is a genetic disease that alters the body's ability to regulate iron absorption. HH causes the body to absorb too much iron. Over time - several years - this excess iron is deposited in the cells of the liver, heart, pancreas, joints and pituitary gland, leading to diseases such as cirrhosis of the liver, liver cancer, diabetes, heart disease and joint disease. HH is easily and effectively treated, but if untreated, it can lead to severe organ damage. 

Hemophilia :

Hemophilia is a bleeding disorder that slows down the blood clotting process.People who have hemophilia often have longer bleeding after an injury or surgery. People who have severe hemophilia have spontaneous bleeding into the joints and muscles. Hemophilia occurs more commonly in males than in females.

Holoprosencephaly:

Holoprosencephaly is a relatively common birth defect of the brain, which often can also affect facial features, including closely spaced eyes, small head size, and sometimes clefts of the lip and roof of the mouth, as well as other birth defects.

Huntington's disease:

Huntington's disease is an inherited neurological illness causing involuntary movements, severe emotional disturbance and cognitive decline.

Inborn Errors of Metabolism:

Metabolism is a sequence of chemical reactions that take place in cells in the body. These reactions are responsible for the breakdown of nutrients and the generation of energy in our bodies. Inborn errors of metabolism (IEM) are a group of disorders that causes a block in a metabolic pathway leading to clinically significant consequences.

Klinefelter syndrome:

Klinefelter syndrome is a condition that occurs in men as a result of an extra X chromosome. The most common symptom is infertility.

Marfan syndrome:

Marfan syndrome is one of the most common inherited disorders of connective tissue. There is a wide variability in clinical symptoms in Marfan syndrome with the most notable occurring in eye, skeleton, connective tissue and cardiovascular systems.

Methylmalonic acidemia:

Methylmalonic acidemia refers to a group of inherited disorders in which the body is unable to process certain proteins and fats (lipids) properly.

Myotonic dystrophy:

Myotonic dystrophy is an inherited type of muscular dystrophy that affects the muscles and other body systems.

Neurofibromatosis:

Neurofibromatosis is a genetic neurological disorder that can affect the brain, spinal cord, nerves and skin. Tumors, or neurofibromas, grow along the body's nerves or on or underneath the skin. 

Noonan syndrome:

Noonan syndrome is a disorder that involves unusual facial characteristics, short stature, heart defects present at birth, bleeding problems, developmental delays, and malformations of the bones of the rib cage.

Osteogenesis imperfecta:

Osteogenesis imperfecta is a genetic disorder that causes a person's bones to break easily, often from little or no apparent trauma.