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Galactosemia (British galactosaemia) is a rare genetic metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly. Galactosemia follows an autosomal recessive mode of inheritance that confers a deficiency in an enzyme responsible for adequate galactose degradation. Friedrich Goppert (1870–1927), a German physician, first described the disease in 1917, with its cause as a defect in galactose metabolism being identified by a group led by Herman Kalckar in 1956. Its incidence is about 1 per 60,000 births for people of European ancestry. In other populations the incidence rate differs. Galactosemia is ten times more common within the Irish Traveller population. == Cause == Image:Lactose Haworth.svg|Lactose File:Beta-D-Glucopyranose.svg|Glucose File:Beta-D-Galactopyranose.svg|Galactose Lactose in food (such as dairy products) is broken down by the enzyme lactase into glucose & galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose are severely diminished or missing entirely, leading to toxic levels of galactose 1-phosphate in various tissues as in the case of classic galactosemia, resulting in hepatomegaly (an enlarged liver), cirrhosis, renal failure, cataracts, vomiting, seizure, hypoglycemia, lethargy, brain damage, & ovarian failure. Without treatment, mortality in infants with galactosemia is about 75%. Galactosemia is inherited in an autosomal recessive manner, meaning a child must inherit one defective gene from each parent to show the disease. Heterozygotes are carriers, because they inherit one normal gene & one defective gene.〔(Galactosemia ) The University of Utah, Genetics Science Learning Center. 2008.〕 Carriers show no symptoms of galactosemia. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「galactosemia」の詳細全文を読む スポンサード リンク
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