Last updated:
1/30/24
Years published: 1987, 1990, 1996, 1998, 1999, 2007, 2010, 2013, 2016, 2020, 2024
NORD gratefully acknowledges Henry C. Lin, MD, pediatric gastroenterologist in the Division of Gastroenterology at Doernbecher Children’s Hospital, Oregon Health & Science University, for assistance in the preparation of this report.
Alagille syndrome (ALGS) is a rare genetic disorder that can affect multiple organ systems of the body including the liver, heart, skeleton, eyes and kidneys. The specific symptoms, organ system involvement and severity of Alagille syndrome can vary greatly from one person to another, even within the same family. Some individuals may have mild forms of the disorder while others may have more serious forms. Common symptoms, which often develop during the first three months of life, include blockage of the flow of bile from the liver (cholestasis), yellowing of the skin and mucous membranes (jaundice), poor weight gain and growth and severe itching (pruritis). Additional symptoms include heart murmurs, congenital heart defects, vertebral (back bone) differences, thickening of the ring that normally lines the cornea in the eye (posterior embryotoxon) and distinctive facial features. Most people with Alagille syndrome have changes (variants or mutations) in one copy of the JAG1 gene. A small percentage (2%) of patients have variants in the NOTCH2 gene. These variants can be inherited in an autosomal dominant pattern, but in about half of cases, the variant occurs as a new change (de novo) in the individual and was not inherited from a parent. The current estimated incidence of ALGS is approximately 1/30,000 –1/45,000.
The symptoms and severity of Alagille syndrome can vary greatly from one person to another, even among members of the same family. Some individuals may have a mild form of the disorder that can virtually go unnoticed; other individuals may have a serious form of the disorder that can potentially cause life-threatening complications. It is important to note that affected individuals may not have all of the symptoms discussed below. Affected individuals should talk to their physician and medical team about their specific case, associated symptoms and overall prognosis.
Alagille syndrome can be associated with abnormalities of the liver, heart, eyes, skeleton, kidneys and other organ systems of the body. A main finding of Alagille syndrome is liver disease that often becomes apparent within the first three months of life. However, individuals with mild liver involvement may not be diagnosed until later in life. Liver disease in Alagille syndrome, if present, may range in severity from asymptomatic mild elevation of liver enzymes to jaundice or mild cholestasis to severe, progressive liver disease that can potentially result in liver failure.
Approximately 90% of individuals with Alagille syndrome have a reduced number of bile ducts (bile duct paucity) within the liver. Bile ducts are small tube-like structures that carry bile from the liver to the small intestines. The formation of bile is one of the functions of the liver. Bile is a fluid that contains water, certain minerals that carry an electric charge (electrolytes) and other materials including bile salts, phospholipids, cholesterol and an orange-yellow pigment (bilirubin) that is a byproduct of the natural breakdown of the hemoglobin of red blood cells. Bile flow accomplishes two important tasks within the body: it aids in digestion and absorption of dietary fats, vitamins, and other nutrients and helps eliminate excess cholesterol, bilirubin, waste and toxins from the body. Therefore, a problem with bile flow often results in malabsorption of vital nutrients and the accumulation of toxic materials in the body.
Because of the reduced number of bile ducts, individuals with Alagille syndrome can develop jaundice and cholestasis usually during the first four months of life. Cholestasis refers to reduced or obstructed flow of bile from the liver. Cholestasis can cause yellowing of the skin (jaundice) or of the whites of the eyes (icterus), itching (pruritus) that may be intense, pale-colored stools, dark urine, fatty bumps (xanthomas) just under the surface of the skin and an abnormally enlarged liver (hepatomegaly) and/or enlarged spleen (splenomegaly). In cholestasis, because the body cannot properly absorb fats and fat-soluble vitamins (vitamins A, D, E, and K), affected children may also have growth deficiencies and difficulty growing and gaining weight (failure to thrive). Malabsorption of vital nutrients can also lead to rickets, a condition marked by softened, weakened bones (vitamin D deficiency), vision problems (vitamin A deficiency), poor coordination and developmental delays (vitamin E deficiency) and blood clotting problems (vitamin K deficiency).
In approximately 15% of patients, progressive liver disease results in scarring of the liver (cirrhosis) and liver failure. There is no way to tell which children are at risk for serious, progressive liver disease in Alagille syndrome.
Many individuals with Alagille syndrome have heart (cardiac) abnormalities that can range from benign heart murmurs to serious structural defects. A heart murmur is an extra sound that is heard during a heartbeat. Heart murmurs in children with Alagille syndrome are usually caused by narrowing of the blood vessels of the lungs (pulmonary artery stenosis). The most common heart abnormality is peripheral pulmonary stenosis in which some of the blood vessels carrying blood to the lungs (pulmonary arteries) are narrowed (stenosis). Some children with Alagille syndrome may have complex heart defects, the most common of which is tetralogy of Fallot. Tetralogy of Fallot is a rare form of cyanotic heart disease. Cyanosis is abnormal bluish discoloration of the skin and mucous membranes that occurs due to low levels of circulating oxygen in the blood.
Tetralogy of Fallot consists of a combination of four different heart defects: ventricular septal defect, obstructed outflow of blood from the right ventricle to the lungs due to an abnormal narrowing of the opening between the pulmonary artery and the right ventricle of the heart (pulmonary stenosis), displaced aorta that causes blood to flow into the aorta from both the right and left ventricles and abnormal enlargement of the right ventricle.
Additional heart defects that can occur in Alagille syndrome include ventricular septal defects, atrial septal defects, patent ductus arteriosus and coarctation of the aorta. Some studies have shown that in rare cases there is an association with Wolff-Parkinson-White syndrome, a condition characterized by electrical disturbances in the heart. (For more information on these disorders, choose the specific disorder name as your search term in the Rare Disease Database.)
Some individuals with Alagille syndrome may have eye (ocular) abnormalities, especially posterior embryotoxon, a condition marked by a prominent line of Schwalbe which results in a thickened ring around the cornea in the eye. The cornea is the thin, transparent membrane that covers the eyeballs. In most cases, posterior embryotoxon is a benign finding that primarily helps to establish a clinical diagnosis and vision is usually unaffected, although mild decreases in the clarity of vision may occur. Less commonly, other eye abnormalities may occur such as optic disk drusen or progressive degeneration of the retina (pigmentary retinopathy). The retina is the thin layer of nerve cells that lines that inner surface of the back of the eyes and senses light and converts it to nerve signals, which are then relayed to the brain through the optic nerve.
Individuals with Alagille syndrome usually have distinctive facial features including deeply set and widely spaced (hypertelorism) eyes, a pointed chin, broad forehead, and low-set, malformed eyes. In older individuals and adults, the chin may appear larger and more prominent (prognathia).
Skeletal abnormalities may occur in some individuals with Alagille syndrome including butterfly vertebrae, a condition in which certain bones of the spinal column are irregularly shaped. This condition is often noted on an X-ray, but usually does not cause any symptoms or problems (asymptomatic).
Additional symptoms may occur in some individuals with Alagille syndrome including kidney (renal) abnormalities, pancreatic insufficiency, vascular anomalies, mild developmental delays and cognitive impairment. Kidney abnormalities may be more prevalent in individuals with Alagille syndrome caused by variants in the NOTCH2 gene and include abnormally small kidneys, cysts on the kidneys and decreased or impaired kidney function. The pancreas is a small organ located behind the stomach that secretes enzymes that travel to the intestines and aid in digestion. The pancreas also secretes other hormones such as insulin, which helps to break down sugar. Pancreatic insufficiency is when the pancreas cannot produce or transport enough enzymes to the intestines to aid in the breakdown and absorption of food and nutrients.
Individuals with Alagille syndrome can also develop abnormalities of certain blood vessels (vascular anomalies) including those in the brain, liver, lungs, heart and kidneys. Vascular anomalies in the brain can lead to bleeding inside the brain (intracranial bleeding) and stroke. Some individuals with Alagille syndrome have developed a condition known as Moyamoya syndrome. Moyamoya syndrome is a progressive disorder characterized by narrowing (stenosis) and/or closing (occlusion) inside the skull of the carotid artery, the major artery that delivers blood to the brain. Intracranial bleeding and other vascular anomalies are potentially life-threatening complications and account for a significant percentage of mortality and morbidity in Alagille syndrome.
Alagille syndrome is caused by variants in one of two genes – the JAG1 gene or the NOTCH2 gene. Variants in the JAG1 gene have been identified in approximately 94% of patients. Variants in the NOTCH2 gene have been found in 2-4% of patients. These gene variants are inherited in an autosomal dominant pattern. In some people, the variant occurs randomly due to a spontaneous genetic change (de novo).
Dominant genetic disorders occur when only a single copy of a gene with a disease-causing variant is necessary for the appearance of the disorder. The variant can be inherited from either parent or can be the result of a new variant (gene change) in the affected individual. The risk of passing the variant from an affected parent to a child is 50% for each pregnancy. The risk is the same for males and females.
Alagille syndrome affects males and females in equal numbers. The incidence of Alagille syndrome has been estimated to be approximately 1 in 30,000-45,000 individuals in the general population. Some cases of Alagille syndrome may go undiagnosed or misdiagnosed making it difficult to determine the true frequency of Alagille syndrome in the general population.
A diagnosis of Alagille syndrome is made based upon identification of characteristic symptoms and genetic testing, along with a detailed patient history, a thorough clinical evaluation and other specialized tests. Because the symptoms of Alagille syndrome are highly variable, obtaining a diagnosis can be difficult. Surgical removal and microscopic study of liver tissue (liver biopsy) can reveal bile duct paucity. Although bile duct paucity is considered a key characteristic of Alagille syndrome, this finding is not always present in infants with the disorder.
A physician may suspect Alagille syndrome if an individual has three of the following five clinical findings in addition to bile duct paucity: symptoms of liver disease or cholestasis, heart defect, skeletal abnormality, eye (ophthalmologic) abnormality and/or distinctive facial features.
In addition to a liver biopsy, physicians may conduct other tests to aid in the diagnosis of Alagille syndrome. Such tests may include blood tests to determine liver function and detect fat-soluble vitamin deficiencies, an eye examination, X-rays of the spine to detect characteristic changes such as butterfly vertebrae, an abdominal ultrasound of the hepatobiliary tree (e.g., liver, pancreas, gall bladder and spleen) to detect abnormalities or rule out other conditions and an examination of heart structure and function to detect potential heart abnormalities.
The diagnosis of Alagille syndrome can be confirmed in many cases by molecular genetic testing, which reveals the presence of a JAG1 or NOTCH2 gene variant. However, in some people with Alagille syndrome, genetic testing may not reveal a JAG1 or NOTCH2 variant.
The treatment of Alagille syndrome is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, gastroenterologists, cardiologists, ophthalmologists and other healthcare professionals may need to plan an affect child’s treatment systematically and comprehensively. Individuals with Alagille syndrome should have a baseline echocardiogram (ultrasound of the heart) to screen for heart involvement, ultrasound of the abdomen to screen for liver and kidney anomalies, a chest X-ray to screen for skeletal involvement, and a screening eye (ophthalmology) exam. In addition, if not previously obtained for specific symptoms, a screening imaging study of the blood vessels of the head (MRI/MRA) is recommended for children who are old enough to sit through the study without need for anesthesia or sedation. Supplemental treatment with vitamins and nutrients is essential for individuals with malabsorption. Such treatment may include restoring vitamins A, D, E and K. Young children may be given formula with medium chain triglycerides because this form of fat is better absorbed by individuals with Alagille syndrome who have cholestasis. Some affected children may need to receive extra calories through a tube that runs from the nose to the stomach (nasogastric tube) or through a tube placed directly into the stomach through a small incision in the abdominal wall and stomach (gastrostomy tube).
Specific treatment may be indicated for individuals with cholestatic liver disease. The drug ursodeoxycholic acid is given to help improve bile flow, which can lead to a reduction in some symptoms such as itching (pruritus) or cholesterol deposits (xanthomas). However, pruritus associated with Alagille syndrome often is resistant to therapy. In 2021, maralixibat (Livmarli) was approved by the U.S. Food and Drug Administration (FDA) to treat pruritus in patients with Alagille syndrome. In 2023, odevixibat (Bylvay) was approved by the FDA to treat pruritus in patients over 12 months of age with Alagille syndrome. Additional drugs that have been used to treat pruritus include antihistamines, rifampin, cholestyramine and naltrexone. Keeping the skin properly hydrated with moisturizers is also recommended. Cholestyramine may also be indicated for individuals with elevated cholesterol levels or xanthomas.
Some affected infants and children with Alagille syndrome who do not respond to drug and dietary therapies may be treated by a surgical procedure known as partial biliary diversion. This surgical procedure is used to disrupt or divert recirculation of bile acids between the liver and the gastrointestinal tract. This therapy has demonstrated that, in some children, it can improve certain symptoms such as reducing itchiness or xanthoma formation.
In severe cases of Alagille syndrome (i.e., cases that have progressed to cirrhosis or liver failure or in which other therapies were unsuccessful), liver transplantation may be required.
Additional complications that can be associated with Alagille syndrome including heart, blood vessel and kidney abnormalities are treated in the standard manner. In some cases, this may include surgery.
Genetic counseling is recommended for affected individuals and their families. Other treatment is symptomatic and supportive.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website: https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact: www.centerwatch.com
For information about clinical trials conducted in Europe, contact: https://www.clinicaltrialsregister.eu/
Contact for more information about this condition:
Henry Lin, MD
Professor of Pediatrics
Division of Gastroenterology
Doernbecher Children’s Hospital
[email protected]
TEXTBOOKS
Jones KL. Ed. Smith’s Recognizable Patterns of Human Malformation. 6th ed. Elsevier Saunders, Philadelphia, PA; 2006:670-671.
Mulberg AE, Rovner A. Alagille Syndrome. NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:332-333.
JOURNAL ARTICLES
Kamath BM, Bauer RC, Loomes KM, Chao G, Gerfen J, Hutchinson A, Hardikar W, Hirschfield G, Jara P, Krantz ID, Lapunzina P, Leonard L, Ling S, Ng VL, Hoang PL, Piccoli DA, Spinner NB. NOTCH2 mutations in Alagille syndrome. J Med Genet. 2012;49:138-44.
Penton AL, Leonard LD, Spinner NB. Notch signaling in human development and disease. Semin Cell Dev Biol. 2012;23:450-7.
Emerick KM, Elias MS, Melin-Aldana H, et al. Bile composition in Alagille syndrome and PFIC patients having partial exnternal biliary diversion. BMC Gastroenterol. 2008;8:47.
Ling SC, Congenital cholestatic syndromes: what happens when children grow up? Can J Gastroenterol. 2007;21:743-751.
McDaniell R, Warthen DM, Sanchez-Lara PA, Pai A, Krantz ID, Piccoli DA, Spinner NB. NOTCH2 mutations cause Alagille syndrome, a heterogeneous disorder of the notch signaling pathway. Am J Hum Genet. 2006;79:169-73.
Warthen DM, Moore EC, Kamath BM, et al. Jagged1 (JAG1) mutations in Alagille syndrome: increasing the mutation detection rate. Hum Mutat. 2006;27:436-443.
Kamath BN, Spinner NB, Emerick KM, et al. Vascular anomalies in Alagille syndrome: a significant cause of morbidity and mortality. Circulation. 2004;109:1354-1358.
Emerick KM, Rand EB, Goldmuntz E, et al. Features of Alagille syndrome in 92 patients: frequency and relation to prognosis. Hepatology. 1999;29:822-829.
Li L, Krantz ID, Deng Y, et al. Alagille syndrome is caused by mutations in human Jagged1, which encodes a ligand for Notch1. Nat Genet. 1997;16:243-251.
Alagille D, Estrada A, Hadouchel M, et al. Syndromic paucity of interlobular bile ducts (Alagille syndrome or arteriohepatic dysplasia): review of 80 cases. J Pediatr. 1987;110:195-200.
INTERNET
Scheimann A. Alagille Syndrome. Medscape. Updated June 15, 2023. Available at: https://emedicine.medscape.com/article/926678-overview Accessed Jan 30, 2024.
Spinner NB, Loomes KM, Krantz ID, et al. Alagille Syndrome. 2000 May 19 [Updated 2024 Jan 4]. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1273/ Accessed Jan 30, 2024.
McKusick VA., ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:118450; Last Update: 03/17/2022. Available at: https://www.omim.org/entry/118450 Accessed Jan 30, 2024.
McKusick VA., ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:610205; Last Update:07/14/2016. Available at: https://omim.org/entry/610205 Accessed Jan 30, 2024.
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