Alagille syndrome, also known as ALGS or arteriohepatic dysplasia, is a rare inherited genetic disorder that primarily affects the liver, heart, kidneys, and other systems of the body.
The genetic condition, caused by mutations in the JAG1 or NOTCH2 genes, means that the person has narrow and malformed bile ducts in the liver. Bile causes scarring in the malformed ducts, which stops the liver from properly eliminating waste from the blood stream. It results in bile build up in the liver, leading to a wide range of symptoms. Eventually, the liver may stop working and a transplant may be necessary.
Symptoms can develop from the first few months of life and are usually present in the first two years.
Alagille syndrome is a complex disorder that can affect other parts of the body including the heart, kidneys, blood vessels, eyes, face, and skeleton. The syndrome is equally common in boys and girls.
The incidence of Alagille syndrome is estimated at about 1 in 30,000-45,000 individuals in the general population.
Symptoms
Common symptoms and features of Alagille Syndrome may include:
- Cholestasis: Reduced bile flow from the liver leading to jaundice (yellowing of the skin and eyes), pruritus (itching), and pale stools.
- Liver abnormalities: Enlargement of the liver (hepatomegaly) and/or abnormal liver function tests.
- Cardiac anomalies: Congenital heart defects, particularly involving the pulmonary artery and heart valves, such as peripheral pulmonary artery stenosis and tetralogy of Fallot.
- Facial features: Characteristic facial appearance with a broad forehead, deep-set eyes, and a pointed chin.
- Skeletal abnormalities: Butterfly-shaped vertebrae, rib abnormalities, and bone fractures.
- Ocular manifestations: Posterior embryotoxon (a thickened anterior edge of the iris), optic disc drusen, and other eye abnormalities.
- Renal abnormalities: Renal dysplasia, which may lead to kidney problems and hypertension. These abnormalities are often present from the first week of life.
- Growth failure: Poor growth and weight gain, especially in infancy and early childhood.
Diagnosis
Diagnosing Alagille Syndrome typically involves a combination of clinical evaluation, imaging studies, genetic testing, and laboratory tests. Symptoms vary and it can be difficult to get a confirmed diagnosis.
Caregivers and patients will typically give clinicians a thorough medical history and patients undergo a physical examination, focusing on characteristic features of Alagille syndrome such as cholestasis, cardiac anomalies, and facial dysmorphism. Blood tests are used to assess liver function and detect cholestasis. Ultrasound, magnetic resonance imaging (MRI), or computed tomography (CT) scans may be performed to evaluate liver and cardiac anatomy. Molecular genetic testing is used to identify mutations in the JAG1 or NOTCH2 genes, confirming the diagnosis of Alagille syndrome. Cardiac imaging and ECG are used to detect congenital heart defects, a common presentation for individuals with Alagille syndrome.
Patients may be referred to a genetic specialist on diagnosis; family members may also be screened for the condition at the same time.
Treatment
There is currently no cure for Alagille Syndrome. Management of the condition is focused on increasing the flow of bile from the liver; other treatments address specific symptoms and complications. In particular, there are treatments available to alleviate symptoms of cholestasis, such as jaundice and pruritus. To support growth and development, a healthy diet and vitamin supplements may be suggested, especially for fat-soluble vitamins A, D, E and K.
Serious complications include congenital heart defects; surgical interventions may follow, depending on the anomaly. Regular monitoring will take place focused on renal abnormalities, growth, skeletal problems, and other complications. In severe cases, liver transplantation may be considered.
Summary
Alagille Syndrome is a rare genetic disorder characterised by a constellation of clinical features including cholestasis, congenital heart defects, facial dysmorphism, and other systemic abnormalities. Diagnosis involves a combination of clinical evaluation, imaging studies, genetic testing, and laboratory tests. Treatment focuses on addressing specific symptoms and complications, providing supportive care, and may include medical management, nutritional support, cardiac interventions, and in severe cases, liver transplantation. Early recognition and comprehensive management are essential for optimising outcomes in individuals with Alagille syndrome.
