Epimerase-deficiency galactosemia is not a binary condition.

Area of Science:

• Biochemistry
• Metabolic Disorders
• Genetics

Background:

• Epimerase-deficiency galactosemia stems from impaired UDP-galactose 4 -epimerase (GALE) in galactose metabolism.
• Initially considered benign and peripheral, GALE deficiency also presents as a severe generalized form affecting multiple tissues.

Purpose of the Study:

• To characterize 10 patients diagnosed with hemolysate epimerase deficiency in the neonatal period.
• To assess GALE activity in lymphoblasts, their metabolic response to galactose, and patient galactose metabolism.

Main Methods:

• Assessed GALE activity in transformed lymphoblasts from 10 patients.
• Evaluated lymphoblast metabolic sensitivity to galactose challenge in culture.
• Monitored patient galactose metabolism on and off a galactose-restricted diet.

Main Results:

• A spectrum of GALE activity (15%-64% of control) was observed in lymphoblasts, indicating epimerase deficiency is a continuum disorder.
• Lymphoblasts with lower GALE activity showed elevated galactose-1-phosphate and UDP-galactose, and deficient UDP-glucose.
• Some patients exhibited metabolic abnormalities regardless of diet, suggesting complex galactose metabolism issues.

Conclusions:

• Epimerase deficiency galactosemia is a continuum disorder with a wide range of GALE activities.
• Biochemical abnormalities in lymphoblasts correlate with reduced GALE activity and may indicate clinical relevance.
• Further long-term studies are needed to understand the clinical significance of these findings and the impact of dietary interventions.