EVALUATION OF LOSS OF HETEROZYGOSITY AND MICROSATELLITE INSTABILITY IN HUMAN PTERYGIUM - CLINICAL CORRELATIONS

Aims-To evaluate the incidence of loss of heterozygosity (LOH) and mic rosatellite instability (MI) in pterygia and their possible correlatio n with clinical variables. Methods-50 pterygia, blood, and conjunctiva l specimens were obtained. A personal and family history was recorded for each patient. Amplification of 15 microsatellite markers at region s 17p, 17q, 13q, 9p, and 9q was performed using the polymerase chain r eaction. The electrophoretic pattern of DNA from pterygia was compared with the respective pattern from blood and conjunctiva. Results-LOH i ncidence was the highest at 9p (48%), followed by 17q (42%). Only thre e cases displayed MI. LOH incidence at individual markers was positive ly correlated with recurrence (D9S59, p=0.11 and D9S270, p=0.16), fami ly history of neoplasia (D13S175, p=0.09), altitude of present residen ce (D9S112, p=0.1), duration of the existence of pterygium (D9S144, p= 0.06), and inversely correlated with age (D9S59, p=0.09). Concerning c hromosome arms, LOH was positively correlated with the altitude of pre sent residence (13q and 17p, p=0.03) and duration of the existence of pterygium (13q and 17p, p=0.09). Conclusions-LOH is a common event whe reas MI is a very uncommon one at the examined markers in pterygium, i ndicating the presence of putative tumour suppressor genes implicated in the aetiopathogenesis of the disease. The fact that LOH at 9q31-33 was more frequent in recurrent pterygia and also correlated with known risk factors such as young age and high altitude of residence, implie s a possible predictive value of this finding for postoperative recurr ence.