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[Identification of inborn errors of galactose metabolism in patients with cataracts]
G Vaca-Pacheco1, C Medina, D García-Cruz
1División de Genética, Unidad de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jal., México.
Insights
This study found higher-than-expected levels of galactosemia heterozygotes among children with cataracts, suggesting a potential link between galactose metabolism enzyme deficiencies and cataract development.
Area of Science:
- Biochemistry
- Genetics
- Ophthalmology
Background:
- Congenital and idiopathic cataracts affect numerous patients, with underlying causes often unclear.
- Galactosemia, a metabolic disorder, involves deficiencies in enzymes crucial for galactose metabolism.
Purpose of the Study:
- To investigate the prevalence of galactosemia heterozygosity in patients with cataracts.
- To explore the potential role of galactose metabolism enzyme deficiencies as a risk factor for cataract formation.
Main Methods:
- Enzyme activity assays for galactokinase (GALK) and galactose-1-phosphate uridyl transferase (GALT) were performed.
- Enzyme levels in 133 cataract patients and 18 classic galactosemia patients were analyzed.
- Comparison of heterozygote incidence in cataract patients versus the general population.
Main Results:
- No total deficiencies of GALK or GALT were observed in cataract patients.
- A statistically significant increase in individuals with low GALK (3.19%) and GALT (4.25%) levels was found in cataract patients aged 1 month to 14 years, compared to general population heterozygote frequencies (0.2% for GALK, 0.8% for GALT).
Conclusions:
- Heterozygosity for galactosemia may represent a risk factor for developing cataracts, particularly in pediatric populations.
- These findings suggest potential therapeutic implications for managing cataracts by considering galactose metabolism.
- Further research is warranted to elucidate the precise mechanisms linking galactose metabolism to cataractogenesis.
Abstract:
133 patients with congenital or idiopathic cataracts were studied (94 patients had ages between 1 month and 14 years; 10 patients had ages between 16 and 50 years and 29 patients did not have an age registry) along with 18 patients with a clinical diagnosis of classic galactosemia. The activity of galactokinase (GALAK) and that of erythrocyte galactose-1-phosphate uridyl transferase (GALT) was measured. There were no individuals with a total deficiency of GALK or GALT. The cataract patients of ages between 1 monthly and 14 years, 3 (3.19%) and 4 (4.25%) showed GALK and GALT levels in the range corresponding to the respective heterozygotes. As compared with the expected incidence of heterozygotes in the general population (0.2% for GALK and 0.8% for GALT) we found a significant rise of individuals with low levels of enzymes for the metabolism of galactose. The possibility that heterozygote galactosemic states contribute a risk factor in the development of cataracts and its therapeutic implications are discussed.