ATAXIA-TELANGIECTASIA HETEROZYGOTES AND PATIENTS DISPLAY INCREASED FLUIDITY AND DECREASE IN CONTENTS OF SULFHYDRYL-GROUPS IN RED-BLOOD-CELLMEMBRANES

In red blood cell membranes of ataxia telangiectasia mutated (ATM) hom ozygotes and heterozygotes, decreased values of the corrected fluoresc ence anisotropy and the anisotropy parameter were found, indicating in creased fluidity and decreased microviscosity, respectively. These cha nges in membranes were accompanied by a decrease in SH-groups and an i ncrease in malondialdehyde (MDA) contents. The content of MDA both in homozygotes and in heterozygotes exceeded roughly threefold the respec tive control values. Decreased content of GSH in red blood cells was f ound only in ATM homozygotes. The change most specific for the ATM gen e appears to be the increase in fluidity, since only this parameter di splays the proportionally greater changes in ATM homozygotes compared to ATM heterozygotes. The observations presented here may indicate tha t the ATM gene is expressed in precursors of red blood cells and defic iency of normal AT gene function may produce the changes which persist in circulating cells.