Alagille Syndrome Clinical Care Program

Glossary of Alagille Syndrome and Genetics Terms

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A prenatal procedure used to collect fetal cells from the amniotic fluid surrounding the fetus; these cells can then be used for genetic testing.

Aortic stenosis

Narrowing or obstruction of the heart's aortic valve, which prevents it from opening properly and blocks the flow of blood from the left ventricle to the aorta.


Accumulation of fluids in the abdominal cavity.

Atrial septal defect

(ASD) - a hole in the wall between the two upper chambers of the heart.

Autosomal dominant

When a mutated gene "dominates" over a normally functioning gene; when a person is carrying an autosomal dominant gene, he or she has a 50 percent chance of passing on that mutation to his or her child.

Autosomal recessive

When a normally functional gene can compensate for the other mutated copy of the gene; a person can't be affected by an autosomal recessive condition unless he or she has inherited two copies of the mutated gene, one copy from each of his or her carrier parents.

Axenfeld's anomaly

A developmental eye abnormality consisting of posterior embryotoxon and iris processes to Schwalbe's ring.



A fluid that neutralizes stomach acid.


Fluid made by the liver and stored in the gallbladder; it helps break down fat and rid the body of waste.

Bile acids

Steroid acids found in bile (i.e. taurocholic and glycocholic acids).

Bile ducts

Any of the ducts that convey bile in and from the liver.

Bile duct paucity

Reduced number of bile ducts.


Related to the liver's bile-carrying structures.

Biliary tract

The liver's bile-carrying structures, which are the gallbladder and the bile ducts; also called the biliary system or the biliary tree.

Butterfly vertebrae

A clefting abnormality in vertebrae (small bones that make up the spine) that gives them a "flying butterfly" appearance on X-rays.


Coarctation of the aorta

A birth defect in which the major artery from the heart (the aorta) is narrowed.


A hormone secreted by the duodenum that stimulates the pancreas to produce digestive enzymes.


Reduction in bile flow.

Cholestatic jaundice

Jaundice resulting from an abnormality in the flow of bile.


A soft, fat-like waxy substance found in the bloodstream and in all your body's cells. Cholesterol is made by the liver and is also absorbed by the body from food.

Chorionic villus sampling

A prenatal procedure used to collect cells from the placenta early in the pregnancy; these cells can then be used for genetic testing.


A chronic liver condition caused by scar tissue and cell damage.


DNA (deoxyribonucleic acid)

The molecule that encodes the genes responsible for the structure and function of living organisms; it allows the transmission of genetic information from generation to generations.


The upper part of the small intestine.


The study of normal and abnormal formation of the body.



The presence of abnormally large amounts of fluid in certain spaces of the body.

Elemental formula

A nutritionally complete formula that requires little or no digestion. It contains a mixture of pure amino acids, simple sugars, essential fatty acids and chemically pure vitamins and minerals that are predigested and made into an easily absorbed formula.

Enteral nutrition

Nutritional support given via any route connected to the gastrointestinal system. Oral feeding, sip feeding, and feeding using nasogastric, gastrostomy and jejunostomy tubes are all enteral nutrition.


The parts of the gene that code for the protein product.


Failure to thrive

Physical and developmental retardation in infants and small children. Characteristics can include poor growth and below normal achievement of fine and gross motor, social-adaptive and language skills.

Fat-soluble vitamins

The four fat-soluble vitamins — A, D, E and K — that travel with fat. Any condition that interferes with the normal absorption of fats would result in poor absorption of these vitamins.


The formation of fibrous tissue, fibroid or fibrous degeneration. It can also represent a scarring of tissue.


Gastrostomy tube

Often called a "g-tube" - a feeding tube placed into the stomach for people who cannot take enough food by mouth to maintain their nutrition. It may be needed temporarily or permanently.


The study of genes and heredity.

Gonadal mosaicism

When a subset of gonadal cells (egg or sperm cells) contains the same gene mutation, but the mutation is not found in any other cells of the body.



Enlargement of the liver.


Main cell type in the liver.


too much bilirubin in the blood; symptoms include jaundice.


Intrahepatic bile duct paucity

Too few bile ducts.


Extra DNA located between exons on the gene.



The gene known to cause Alagille syndrome, which codes for a cell surface protein that functions in the Notch signaling pathway.


Yellowish skin color caused by bile buildup in the blood.



Any of a heterogeneous group of fats and fatlike substances characterized by being water-insoluble.

Liver enzyme tests

Also called liver function tests; test that evaluate how well the liver and biliary system are working.


Medium-chain tryglycerides

Dietary fats that are digested and absorbed differently from other dietary fats; helpful in treating fat malabsorption.


Nasogastric feeding

Delivering liquid nutrients through a tube passing through the nose into the stomach. This is used when children are unable to consume adequate calories.

Neonatal hepatitis

Hepatitis of unknown cause that occurs in the first few weeks of life.


A second gene that has been found to cause Alagille syndrome in a few patients who do not have mutations in Jagged1.


Obstructive jaundice

Jaundice which is caused by an impediment to the flow of bile from the liver cells to the duodenum.


Pancreatic insufficiency

When the pancreas fails to produce enough of the enzymes necessary for food digestion.

Peripheral pulmonary stenosis

Narrowing of the lung vessels well away from the heart.

Portal hypertension

High blood pressure in the portal vein that carries blood to the liver; a common complication of cirrhosis.

Posterior embryotoxon

A thin line seen at the edge of the iris. It does not affect vision in any way.


Severe itching.


related to the lungs.



The membrane that lines the back chamber of the eye; it converts the images sent by the lens (at the front of the eye) into chemical and nervous signals for the brain.


A condition caused by a deficiency of vitamin D, especially in infancy and childhood, that interferes with normal bone formation.



Excessive amounts of fats in the feces; this occurs in malabsorption syndromes.


Tetralogy of Fallot

A congenital (present at birth) heart defect often associated with Alagille syndrome; for more detailed information, please see the Tetralogy of Fallot page in our Cardiac Center website.


Ventricular septal defect

(VSD) - one or more holes in the muscular wall that separates the right and left ventricles of the heart; for more detailed information, please see the ventricular septal defect page in the Index of Medical Conditions.



Bumps on the skin resulting from fat deposits; usually seen at the creases at the elbows, knees and the diaper line.

Reviewed by: Bimita M. Kamath, MD
Date: January 2009

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