Loss of heterozygosity in pseudoexfoliation syndrome

PURPOSE. Pseudoexfoliation (PEX) syndrome is characterized by the accumulat ion of a material of unknown origin in the anterior structures of the eye. Loss of heterozygosity (LOH) in a genetic locus indicates the presence of a gene located in the same region that could be implicated in the developmen t or the progression of a disease. In this study, the occurrence of LOH in tissues involved in PEX and the possible correlation of LOH incidence with clinical parameters were evaluated. METHODS. Twelve iris specimens, 12 anterior capsule specimens, and respecti ve blood samples were obtained from 17 patients with PEX (13 men), who were undergoing glaucoma and cataract surgery. Sixteen anterior capsule specime ns and four iris specimens mere obtained from 16 patients without PEX. Poly merase chain reaction was used to amplify 10 highly polymorphic microsatell ite markers located on chromosomes 1, 7, 9, and 13. RESULTS. Overall, 83.3% (20/24) of PEX specimens and 94.11% (16/17) of pati ents with PM had LOH. The highest incidence of LOH was observed in marker D 13S175 (41.6%) followed by D7S478 and D7S479 (37.5%). Only three non-PEX sp ecimens displayed LOH. The number of loci lost was directly related to the altitude of the patients' present residence, but the number lost did not di ffer significantly between the iris and capsule samples. CONCLUSIONS. The occurrence of LOH in tissues involved in PEX implies a gen etic role in PEX pathogenesis at a cellular level. The correlation of LOH i ncidence with the altitude of the patient's residence, could indicate an in creased susceptibility, to UV radiation of the chromosomal regions examined .