Classic Galactosemia: Study on the Late Prenatal Development of GALT Specific Activity in a Sheep Model.

Classic galactosemia results from deficient activity of galactose-1-phosphate uridylyltransferase (GALT), a key enzyme of galactose metabolism. Despite early diagnosis and early postnatal therapeutic intervention, patients still develop neurologic and fertility impairments. Prenatal developmental toxicity has been hypothesized as a determinant factor of disease. In order to shed light on the importance of prenatal GALT activity, several studies have examined GALT activity throughout development. GALT was shown to increase with gestational age in 7-28 weeks human fetuses; later stages were not investigated. Prenatal studies in animals focused exclusively on brain and hepatic GALT activity. In this study, we aim to examine GALT specific activity in late prenatal and adult stages, using a sheep model. Galactosemia acute target-organs-liver, small intestine and kidney-had the highest late prenatal activity, whereas the chronic target-organs-brain and ovary-did not exhibit a noticeable pre- or postnatal different activity compared with nontarget organs. This is the first study on GALT specific activity in the late prenatal stage for a wide variety of organs. Our findings suggest that GALT activity cannot be the sole pathogenic factor accounting for galactosemia long-term complications, and that some organs/cells might have a greater susceptibility to galactose toxicity. Anat Rec, 300:1570-1575, 2017. © 2017 Wiley Periodicals, Inc.

Effects of galactosemia in utero.

There is direct evidence that in galactosemia, due to galactose-1-phosphate uridyltransferase deficiency, galactose, galactose-1-phosphate and galactitol accumulate in the fetus by week 20 of gestation. The metabolic abnormality may develop earlier than this, however, since the key enzymes in galactose metabolism have been shown to be present in normal fetal liver from the 10th week of gestation. There has been a single report of increased galactitol in amniotic fluid obtained at 10 weeks gestation, the outcome being a baby affected with galactosemia. Cataract formation in the fetus is rare and the only direct evidence that galactosemia may have harmful effects in utero. However, it has been concluded that the liver pathology seen in some patients who died in the neonatal period originated prenatally, and some studies have found that galactosemia is associated with reduced birth weight. Reports of two patients with histologically normal ovaries very soon after birth have been cited as evidence against gonadal dysfunction arising during fetal life, but it should be noted that this is not a constant feature in female galactosemics. Other observations, particularly those made from animal models, would suggest that ovarian dysfunction is most likely to have been caused in utero.