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Disturbance of the metabolism of galactose (galactosemia) in children
Last reviewed: 23.04.2024
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Galactosemia is a hereditary disease caused by abnormalities in the metabolism of galactose. Symptoms of galactosemia include impaired liver and kidney function, decreased cognitive function, cataracts and premature ovarian failure. The diagnosis is based on the study of erythrocyte enzymes. Treatment consists of a diet that does not contain galactose. The prognosis for physical development is usually favorable in treatment, but the results of verbal and non-verbal tests for intelligence are often reduced.
ICD-10 code
E74.2 Disturbances in the metabolism of galactose.
Epidemiology of galactosemia
Galactosemia, type I - a panethnic disease, the frequency in European countries is on average 1 per 40 000 live births.
Galactosemia, type II - in Europe, the incidence of the disease is 1 per 150 000 live births. A higher incidence is noted in Romania and Bulgaria. With a high frequency is found in gypsies - 1 in 2500.
Galactosemia, type III is a rare hereditary metabolic disease. Benign form is widespread in Japan (1 in 23,000 newborns).
[What causes galactosemia?
Galactosemia is caused by a hereditary deficiency of one of the enzymes that convert galactose into glucose.
Symptoms of galactosemia
Galactose is present in dairy products, fruits and vegetables; 3 clinical syndromes are caused by inherited autosomal recessive deficit of various enzymes.
Deficiency of galactose-1-phosphaturidyl transferase
With a deficiency of this enzyme, classical galactosemia develops. The frequency is 1/62000 births; the carrier frequency is 1/125. Infants develop anorexia and jaundice within a few days or weeks of ingestion of breast milk or a lactose-containing mixture. Vomiting, hepatomegaly, low physical development, drowsiness, diarrhea and septicemia (usually caused by Escherichia coii), as well as kidney disorders (eg, proteinuria, aminoaciduria, Fanconi syndrome), leading to metabolic acidosis and edema. Hemolytic anemia can also develop. In the absence of treatment, children remain short, develop cognitive impairments, speech, gait and balance in adolescence; many also develop cataracts, osteomalacia (caused by hypercalciuria), and premature ovarian failure. Patients with the Duarte variant have much milder clinical manifestations.
Galactokinase deficiency
Patients develop cataracts due to the production of galactol, which osmotically damages the lens fibers; Idiopathic intracranial hypertension (pseudotumor brain) is rarely noted. The frequency is 1/40 000 births.
Deficiency of uridyl diphosphate-galactose-4-epimerase
There may be benign and severe forms of the disease. The frequency of a benign form is 1/23,000 births in Japan; for more severe forms, the frequency is unknown. The benign form is limited to erythrocytes and leukocytes and does not cause clinical manifestations. The severe form causes a syndrome indistinguishable from classical galactosemia, although sometimes hearing loss is also noted.
Classification of galactosemia
To date, there are three known hereditary diseases due to the deficiency of enzymes involved in galactose metabolism: type I galactosemia (galactose-1-phosphate-uridyltransferase deficiency, classical galactosemia), type II galactosemia (galactokinemia insufficiency), and type III galactosemia (galactose-4 deficiency epimerase).
Diagnosis of galactosemia
The diagnosis is suspected clinically, in its favor the increase in the level of galactose and the presence of reducing substances in urine, except for glucose (for example, galactose, galactose-1-phosphate); confirm the diagnosis by the study of enzymes in erythrocytes, liver tissue. In most states, screening for newborns is required for a deficiency of galactose-1-phosphaturidyl transferase.
Screening for galactosemia
Among these diseases, galactosemia, type I - is the most severe pathology requiring urgent correction. Mass screening of newborns, conducted in many countries, is aimed at identifying precisely this form of galactosemia.
What do need to examine?
How to examine?
What tests are needed?
Treatment of galactosemia
Treatment of galactosemia consists of the exclusion of all sources of galactose from food, primarily lactose, which is the source of galactose present in all dairy products, including artificial mixtures for baby food based on milk, as well as sweeteners used in many types of food. A lactose-free diet prevents acute toxicity and promotes the reverse development of certain symptoms (eg, cataracts), but may not prevent non-cognitive impairment. Many patients require additional calcium and vitamins. For patients with epimerase deficiency, a small amount of galactose must be obtained in order to provide a supply of uridyl-5'-diphosphate galactose (UDP-galactose) for various metabolic processes.