Galactokinase Gene Mutations and Age-related Cataract. Lack of Association in an Italian Population

Abstract

Abstract: : Purpose: To investigate possible associations between changes in the Galactokinase (GalK1) gene and age-related cataract. Methods:Persons without lens opacities and persons with clinically significant age-related cataract were selected from those participating in the Collaborative Italian-American Clinical Trial of Nutritional Supplements and Age-Related Cataract or from those attending the Section of Ophthalmology of the University of Parma for cataract surgery. Type and severity of the opacities were assessed by slit-lamp and retro-illumination lens photographs. Mutations in GalK1 gene were identified by PCR amplification of individual exons and flanking sequences and sequencing using fluorescent terminator technology in an ABI 377 Prism or 3100 automated DNA sequencer. Results: DNA samples were obtained from 115 individuals with clear lenses and from 185 individuals with cataract (106 with any nuclear, 88 with any cortical, and 25 with any posterior sub capsular cataract ). 157 of the 185 patients with cataract (85%) were age-matched with a control within an age range of + 1 yr. Distribution of SNP that did result in an amino-acid change was not significantly different between cases and controls: Exon 4: 1/115 conts vs 0/185 cases, p=0.383; Exon 6: 0/115 conts vs 1/185 cases, p>0.99; Exon 7: 0/115 conts vs 1/185 cases, p>0.99. 78 samples showed a C→T change 43 bases into Intron 7 (SNP rs743554). Testing of Hardy-Weinberg Equilibrium of the Intron 7 findings showed equilibrium for C-T distribution for both cases (p=0.734) and controls (p=0.509). The Breslow test of homogeneity detected no difference in C/T distribution between cases and controls (p=0.872). Conclusions: In this northern Italian population age-related cataract does not appear to be associated to GalK 1 gene mutations. Since this is due to a lack of sequence changes in both affected and control individuals, this study cannot rule out the possibility of an association in other populations.

Keywords: candidate gene analysis • cataract • aging