Galactosemia
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Galactosemia Microchapters |
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Galactosemia On the Web |
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American Roentgen Ray Society Images of Galactosemia |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Dayana Davidis, M.D. [2]
Synonyms and keywords: Classic galactosemia, galactokinase deficiency
Overview
Historical Perspective
Classification
Galactosemia is an inherited rare autosomal recessive trait that leads to the build up of galactose in the blood. The word galactosemia means too much galactose, which is a simple sugar obtained after lactose, the sugar found in dairy products, is broken down by enzymes found in the body into galactose and glucose.
Galactose is converted into glucose by the action of three enzymes, known as the Leloir pathway. Accordingly, there are 3 known types of Galactosemia; type 1, 2 and 3:
Types Of Galactosemia
Galactosemia Type 1
Galactosemia type 1, also called classic galactosemia is the most common form of the disorder and the first form to be discovered. Individuals diagnosed with classic galactosemia have the genetic makeup G/G, which indicates that they have inherited the galactosemia gene from each parent. They have defects in both copies of the gene that codes for the enzyme galactose-1-phosphate uridyl transferase or GALT. Duarte galactosemia is a variant of the classic galactosemia. Individuals with the genetic makeup D/G have one gene for classic galactosemia from one parent, G, and one Duarte gene variant from the other parent. Individuals with Duarte galactosemia will be able to metabolise some galactose as GALT activity in Duarte Galactosemia patients is approximately 20% to 50 %. Patients with Duarte Galactosemia have less severe symptoms than other forms of the disorder.
Galactosemia Type 2
Galactosemia type 2 is less common than classic galactosemia and is less harmful. It does not generally lead to hepatomegaly or brain damage. It is caused by the defect in both copies of the gene that codes for the enzyme galactokinase or GALK.
Galactosemia type 3
Galactosemia type 3 is a very rare form of the disorder. There are two forms of Galactosemia type 3, a severe form and a benign form. This type of galactosemia is caused by defects in the gene that codes for the enzyme uridyldiphosphogalactose-4-epimerase or GALE.
Pathophysiology
Causes
Differentiating Galactosemia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | CT | MRI | Ultrasound | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Surgery | Primary Prevention | Secondary Prevention