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A startling discovery of enormous implication has just been reported in the premier research journal, Science. Despite the accepted dogma that all of a person's cells have the same genetic coding, it turns out that this is not true, especially in neurons. The DNA in each nerve cell (we don't know about sex cells) has hundreds of mutations of the A-T, C-G nucleotides that constitute the genetic code for the neuron. Thus, no two neurons are alike. The study was conducted by 18 research teams at 15 U.S. institutions, formed as a consortium by the National Institute of Mental Health to examine neural genetic coding, using repositories of postmortem brain tissue taken from both healthy people and those with various mental diseases. The scientists have no explanation at present for what is causing so many mutations and why each neuron has a different genetic profile. The most obvious possibility might seem to be that the mutations occurred as transcription errors during cell division...

In recent years scientists have discovered mobile pieces of genetic material that move around inside cells. These pieces are called retrotransposons. They can copy themselves and insert near and into DNA and thus induce mutations. Australian research recently reported in the journal  Nature  reveals that retrotransposons can alter the genome of human brain cells. In fact, retrotransposons more effectively penetrate neuron genes than those in blood cells that were used for comparison. Thousands of retrotransposon mutations were seen in two of the five areas examined from brains of human post-mortem donors. Though these pieces of DNA are not genes, they interact with genes that hop around to different sites within a chromosome (perhaps you heard about Barbara McClintok’s 1983 Nobel Prize winning discovery of “jumping genes”). All cells have enzymes that cut transposons out of a string of DNA, which then insert back in at other locations in the DNA. Sometimes the cut includes an ...