History
Hepatosplenomegaly at birth (reported in a single case) is not common in neonates with galactokinase deficiency.
Failure to develop a social smile or to follow objects may represent initial signs of a visual deficit due to cataracts.
GI symptoms associated with the ingestion of galactose are conspicuously absent.
Growth parameters are unaffected.
Family history is not relevant.
Soy formula (given to the infant for other reasons) may curtail the development of cataracts and delay the consequent diagnosis of galactokinase deficiency. However, milk products introduced into the diet later will result in cataract formation.
Physical
Cataracts may be apparent upon gross inspection of the eye.
Opacities may be visualized during attempts at funduscopic examination.
Vision-based developmental landmarks, such as tracking, reaching, and social smiling, may be reached late or not at all.
Causes
Galactokinase deficiency is an autosomal recessive genetic disorder mapped to band 17q24.
At least 20 mutations are known. The P28T mutation is considered the founder mutationin Romani families from southeastern Europe. [8]
Many genetic variations of GALK1 have been identified in the patients with galactokinase deficiency. [9, 10]
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UDP-galactose synthesis and galactosemia. The most common form of galactosemia is due to a deficiency of galactose-1-phosphate uridyltransferase (GALT). This enzyme normally uses galactose-1-phosphate derived from dietary galactose. In the absence of GALT, galactose-1-phosphate accumulates, along with excessive galactose and its oxidative and reductive products galactitol and galactonate (not shown). UDP-galactose synthesis may also be impaired in the absence of GALT but not completely because UDP-galactose-4′-epimerase (GALE) can form UDP-galactose from UDP-glucose and can supply the donor to galactosyltransferases required for normal glycoconjugate biosynthesis.
