Possible role of galactose-1-P-uridyl transferase activity deficiency in red blood cells in the development of the presenile and senile cataract

Synergistic effect of high lactase activity genotype and galactose-1-phosphate uridyl transferase (GALT) mutations on idiopathic presenile cataract formation

OBJECTIVES

To evaluate the possible synergistic role of partial galactose metabolism defects, high lactase (LPH) genotype and lactose and galactose ingestion in presenile cataract formation.

DESIGN AND METHODS

51 patients with idiopathic presenile cataracts and 172 healthy cataract-free subjects were genotyped to determine their galactose-1-phosphate uridyl transferase (GALT) and LPH status. Whole milk, skimmed milk and yoghurt consumption was recorded in 19 cataract patients and 172 controls by questionnaire.

RESULTS

GALT mutations and whole milk consumption increased the risk of cataract formation in high LPH genotype group, but not in lactose intolerant subjects. Logistic regression analysis showed the synergistic effect of GALT and LPH mutations on cataract formation.

CONCLUSIONS

High lactase activity genotypes and mutations in galactose-1-phosphate uridyl transferase have a synergistic effect on presenile cataract formation.

Mutations in galactose-1-phosphate uridyltransferase gene in patients with idiopathic presenile cataract

Impaired activity of the enzyme galactose-1-phosphate uridyltransferase (GALT) has been proposed as a risk factor for idiopathic presenile cataract. A study was undertaken to determine the prevalence of the three most common mutations in the GALT gene (Q188R, K285N and N314D, including its variant Duarte-2) in a group of Slovenian patients with idiopathic presenile cataract. GALT activity was determined in the erythrocytes of 30 cataract patients. DNA was isolated from their blood and analysed for Q188R, K285N and N314D mutations and IVS5-24G>A intronic variation by means of polymerase chain reaction and digestion with restriction enzymes. The average GALT activity of the cataract group was 19.5+/-4.9 U/g Hb, which is lower than the normal range (p = 0.034). Frequencies of Q188R, K285N, N314D and Duarte-2 alleles in the cataract group were 0.00%, 5.0%, 11.7% and 3.3%, respectively. Only the frequency of the K285N mutation was significantly higher in the patient group than in the control group (p = 0.0244). Our results support the reported association of decreased GALT activity with idiopathic presenile cataract. Molecular analysis indicates that, in the Slovenian population, this association is linked to the K285N mutation, which is neonatally benign in heterozygotes.

Galactose-1-P-uridyl transferase activity in patients with congenital and infantile cataract

The activity of red blood cell galactose-1-P-uridyl transferase in 22 patients with congenital and infantile cataract and in 18 age-matched controls was investigated. All control subjects examined showed normal enzymatic levels, while 31.8% of patients with congenital and infantile cataract presented a statistically significant reduced enzymatic activity (mean--2 SD in controls). Twenty-four parents of children with congenital and infantile cataract were also examined. Four parents were affected by congenital cataract and the other 20 showed transparent lenses. The parents were compared with a group of 20 age-matched control subjects examined previously. There was no difference in the average enzymatic activities between the groups. The results suggest that a chronic disorder of galactose metabolism may be involved in the development of congenital and infantile cataract.