OMIM ID:
Galactosemia
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
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.
Systemic Features
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.
Genetics
Inheritance
This is an autosomal recessive disorder resulting from mutations in the GALT gene (9p13) encoding galactose-1-phosphate uridylyltransferase.
For other disorders of galactose metabolism see galactose epimerase deficiency (230350) and galactokinase deficiency (230200).
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.