Deficiencies in both galactokinase (GALK) and galactose-1-phosphate uridyltransferase (GALT) result in galactosemia. Which of the following additional symptoms would be useful in a differential diagnosis to confirm GALK deficiency from GALT deficiency?

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GALK deficiency specifically leads to the accumulation of galactitol, which causes lenticular cataracts, distinguishing it from GALT deficiency.  Patients with GALK deficiency often present with cataracts that will resolve upon dietary restriction of galactose. However, although patients with classic galactosemia (GALT deficiency) also can develop cataracts, the prevalence among classic galactosemics is markedly less than among GALK-deficient patients due to the extremely high levels of galactitol found in the latter.

Deficiencies in Both Galactokinase (GALK) and Galactose-1-Phosphate Uridyltransferase (GALT) Result