IN-VIVO ACCUMULATION OF 8-HYDROXY-2'-DEOXYGUANOSINE IN DNA CORRELATESWITH RELEASE OF REACTIVE OXYGEN SPECIES IN FANCONI ANEMIA FAMILIES

The present study was aimed at verifying the occurrence, if any, of in vivo oxidative DNA damage in FA homozygotes, their parents and siblin gs, 8-Hydroxy-2'-deoxyguanosine (8-OHdG) was measured, by HPLC/EC, in DNA from circulating blood leucocytes from FA homozygotes and their re latives and compared with a group of paediatric and adult healthy subj ects, The]population studied consisted of: (i) 15 FA homozygotes; (ii) 24 FA heterozygotes; (iii) 11 siblings, The 8-OHdG level in FA homozy gotes was significantly higher with respect to age-matched controls, w ith a mean level of 33.3 +/- 6.8 (mean +/- SE) and 3.9 +/- 0.26 8-OHdG /10(5) dG respectively, The FA parents (heterozygotes) also displayed higher 8-OHdG levels relative to controls, The release of hydroxyl ((O H)-O-.) and (OH)-O-.-like radicals from leucocytes was determined by l uminol-dependent chemiluminescence (LDCL) in a subgroup of FA homo- an d heterozygotes, showing a very large in vivo formation of non-superox ide radicals, Chromosomal instability was also measured in the FA popu lation, When relating either 8-OHdG or LDCL levels to spontaneous or d iepoxybutane-induced chromosomal instability (S-CI and DEB-CI respecti vely), a significant correlation was observed between the 8-OHdG, LDCL and S-CI data, Within families a positive association was found betwe en 8-OHdG levels in homozygotes and their related heterozygotes, sugge sting segregation of the genetic defect(s) underlying the abnormal oxi dative metabolism, The present study provides evidence for an in vivo pro-oxidant state in FA, in terms of excess formation of (OH)-O-. and (OH)-O-.-like radicals, and of DNA hydroxyl adducts, This finding appe ars to be shared by homozygotes and, to a lesser extent, by heterozygo tes.