Galactosemia 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.
Neonatal cataracts are found among at least 30% of infants with this disorder. However, early (before 17 days of age) dietary restrictions can prevent their formation or even lead to regression. They result from the osmotic imbalance caused by the presence of accumulated galactitol. Neonates may suffer vitreous hemorrhages from the coagulopathy but this is rare.
In spite of early and adequate treatment, however, many adults have residual problems. Cataracts have been found in 21%, decreased bone density in 24%, tremor in 46%, ataxia in 15%, and dysarthria in 24%. Few patients of either sex have children and all females have premature ovarian insufficiency. Depression and anxiety are present in 39-67%. It has been estimated that there is a twofold increase in the odds of depression with each 10 year increment of age.
This is an autosomal recessive disorder resulting from mutations in the GALT gene (9p13) encoding galactose-1-phosphate uridylyltransferase.
Treatment with a lactose- and galactose-free diet within the first 3-17 days can prevent the formation of cataracts. Few need surgical removal. Liver function improves and a reduction in icterus can be seen. It can also prevent fatal E. coli sepsis. However, long term effects have been disappointing as many patients still develop mental and motor dysfunction as well as speech difficulties (dyspraxia). The long term outcome seems to depend upon the level of GALT enzyme activity which varies considerably.