galactosemia II

Galactokinase Deficiency

Clinical Characteristics
Ocular Features: 

This is a considerably more rare disorder of galactose metabolism compared with classic galactosemia (230400).  Both disorders cause cataracts in the neonatal period but the early systemic effects of galactokinase deficiency are less severe.  In the latter disorder, cataracts usually develop later, often during the first decade of life and less commonly during the neonatal period that is characteristic of classic galactosemia.  Galactitol  accumulation causing osmotic changes in the lens accounts for the cataracts and may also be responsible for the development of pseudotumor cerebri found infrequently.  Good dietary control may prevent the formation and progression of cataracts and it has been reported that they may regress as well but only prior to the rupture of cell membranes.

Systemic Features: 

Late complications include abnormalities in mental and/or motor development, dyspraxia, and hypogonadotropic hypogonadism which occur in spite of severe reduction in galactose intake.  Ovarian failure is common.

Genetics

This is an autosomal recessive disorder caused by mutations in the GALK1 gene (17q24) encoding galactokinase.  It is extremely rare but should be considered in any patient with cataracts found within the first two decades of life.  Deficient activity of the galactokinase enzyme can be demonstrated in erythrocytes.

For other disorders of galactose metabolism, see galactosemia (230400) and galactose epimerase deficiency (230350).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Early dietary restriction of non-galactose polycarbohydrates and deficient in lactose may prevent the formation of cataracts or sometimes result in regression.

References
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