TRANSCRIPTS OF THE TRANSPOSON MARINER ARE PRESENT IN EPILEPTIC BRAIN

Mobile genetic elements termed transposons have been increasingly impl icated in human disease. The small transposon mariner is widespread wi thin non-vertebrate genomes and causes mutation by replication, excisi on, and insertion of itself without an RNA intermediate. We find that human DNA contains about 60 copies of this gene. Mariner transcripts a re abundant in RNA prepared from sclerotic epileptic hippocampi. In co ntrast, typically no mariner-specific RNA is detected in non-sclerotic hippocampi from other epileptic patients or from autopsies. A complet e but non-functional copy was obtained using rapid amplification of cD NA ends (RACE). This human mariner transcript is similar to 45% homolo gous to a functional counterpart active in Drosophila, with a coding r egion of 1035 bases flanked by 32 base inverted terminal repeats. The differential expression of mariner transcripts within sclerotic hippoc ampi suggests the probable activity of an autonomous element which by mutating critical genes could establish an epileptogenic substrate in the hippocampus. (C) 1998 Elsevier Science B.V. All rights reserved.