IDENTIFICATION AND CHARACTERIZATION OF POLYMORPHISMS IN THE PROMOTER REGION OF THE HUMAN APO-1 FAS (CD95) GENE/

Apo-1/Fas (CD95) is a transmembrane protein expressed on the cell surf ace that is involved in apoptosis and plays an important role in the f unction and regulation of the immune system. Aberrant expression of th e Apo-1/Fas gene product has been reported in a number of immune-relat ed disorders, such as autoimmune lymphoproliferative syndrome and syst emic lupus erythematosus in humans. Mutations in the coding sequence o f the Apo-1/Fas gene have been reported in the former condition, where as no abnormalities of the gene have been found to account for the inc reased gene expression noted in SLE. We screened the whole 5' flanking region of the Apo-1/Fas gene encompassing over 2000 bp for mutation(s )/polymorphism(s) using multiplex PCR, single-strand conformation poly morphism (SSCP) analysis and sequencing techniques, and identified two polymorphisms in this region. The first polymorphism is a CG-->CA sub stitution at -1377 nucleotide position within the silencer region, whi ch neither creates or deletes any restriction enzyme sites but alters the transcription factor SP-1 binding site. This polymorphism is noted in 20% of normal Caucasians. The second polymorphism is an GA-->GG su bstitution at -670 nucleotide position in the enhancer region that cre ates a MvaI restriction fragment length polymorphism (RFLP) and abolis hes the binding site of nuclear transcription element GAS. The MvaI RF LP is polymorphic with heterozygosity of 52% and the frequency of G an d A alleles are 0.49 and 0.51, respectively. The identification and ch aracterisation of these two new polymorphisms, particularly the MvaI R FLP marker, provides new genetic markers and may prove useful for furt her studies on the regulation of apoptosis mediated by the Apo-1/Fas g ene on human chromosome 10 q23. (C) 1997 Published by Elsevier Science Ltd.