Coronavirus Resource Center. Our website uses cookies to enhance your experience. By continuing to use our site, or clicking "Continue," you are agreeing to our Cookie Policy Continue. Twitter Facebook. This Issue. May Access through your institution. Add or change institution. Classic galactosemia, by far the most common variant, involves a deficiency of GALT.
This results in a buildup of galactosephosphate and other precursors, causing damage to many organs, including the liver, spleen, kidney, ocular lens, cardiac muscle, brain, gonadal tissue and erythrocytes. The earlier the disorder is diagnosed and a galactose-free diet is implemented, the less damage will ensue. Even with optimal dietary treatment, developmental delays and learning disabilities are common, and affected women almost invariably suffer premature ovarian failure 2.
Galactosemia has an incidence of approximately one in 60, in North America 3. Several countries have universal newborn screening for galactosemia, but the practice is not widespread. In Canada, only a minority of provinces have a newborn galactosemia screening program in place. More common symptoms and signs suggestive of galactosemia are as follows 4 :. There are also several reports of galactosemic infants presenting with Escherichia coli sepsis 5.
The presence of urinary reducing substances in the absence of glucosuria as detected by a routine dipstick test supports the diagnosis of galactosemia. False-positive and false-negative results are not uncommon. Urinary reducing substances will not be present if the infant is not receiving any dietary galactose ie, infants already switched to a soy-based formula.
The Beutler enzyme spot test is not widely available outside of academic centres but is a more sensitive, rapid test for galactosemia due to GALT deficiency. A recent blood transfusion can cause a false-negative result, while G6PD deficiency results in false-positive results. The confirmatory test red blood cell quantitative GALT assay may take some time, but in the interim, a galactose-free diet should be instituted.
Finally, red blood cell galactosephosphate concentrations are elevated in all causes of galactosemia regardless of the specific enzyme defect, but the test is not widely available.
In the above case, the discordant glucose meter and serum sample glucose concentrations also provided an important clue to the diagnosis. The need to confirm glucose meter checks with serum samples should be emphasized. Some glucose meters will overestimate the serum glucose in the setting of hypergalactosemia due to the lack of specificity of the enzyme used by the assay 6. As well, untreated galactosemic infants like the one described above may be hypoglycemic because a major source of their dietary glucose is, in effect, not available.
Conjugated hyperbilirubinemia in the newborn is always pathological and requires a systematic approach to diagnosis. Common and treatable conditions should be ruled out promptly. Galactosemia is a relatively rare disorder, but early recognition is key to improving outcome. If galactosemia is suspected, a galactose-free diet should be initiated pending confirmatory test results. Those caring for newborns need to be aware that some commercially available glucose meters will overestimate serum glucose levels in the setting of galactosemia.
Google Scholar. Google Preview. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide. Sign In or Create an Account. Galactosemia: when is it a newborn screening emergency? Mol Genet Metab.
Epub Mar Classical galactosaemia revisited. J Inherit Metab Dis. Epub Jul Epimerase Deficiency Galactosemia. Duarte Variant Galactosemia. Ovarian function in girls and women with GALT-deficiency galactosemia. Epub Oct Literature review and outcome of classic galactosemia diagnosed in the neonatal period.
Clin Lab. Epimerase-deficiency galactosemia is not a binary condition. Am J Hum Genet. Epub Nov The molecular basis of galactosemia - Past, present and future. Epub Jul 2. Citation on PubMed.
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