Many think their genetic information is permanent, that whatever we inherit from our parents gene-wise is what we are stuck with — that genes don’t change.
But that’s not the case. Genes cannot only change throughout our lives, but they can move or jump from one place in the genome to another.
Science shows these jumping genes are linked to certain diseases in humans, but they may have positive effects as well.
Most genes are located in the same place on the same chromosomes in everyone. But small pieces of DNA called retrotransposons, or jumping genes, can move to other parts of the genome.
In their new locations, they can stay silent, create their own products or alter the activity of nearby genes. Jumping genes have been implicated in some cancers and neurological disorders.
Autopsies of people with schizophrenia showed their brains had more of these jumping genes than other people. Furthermore, the more a schizophrenic had been exposed to environmental factors known to influence schizophrenia, the more jumping genes they had.
Schizophrenia is a condition that can cause hallucinations, delusions and cognitive defects and occurs in about 1 percent of people. A number of genes and environmental factors are associated with developing schizophrenia.
One such jumping gene called LINE-1 retrotransposon (L1) is particularly abundant in brain stem cells that form into neurons.
It is estimated that the human genome has more than 500,000 copies of L1. Most of these copies are defective, but about 100 are active and able to produce additional L1 that can jump to other locations.
People with a form of autism called Rett Syndrome and those with a neurological motor disease called Louis-Bar syndrome have increased L1. Now, scientists have documented that schizophrenics also have increased L1.
Scientists wanted to know whether the increased L1 levels were because of environmental factors or the development of schizophrenia. First, they injected pregnant mice with a molecule that simulates a viral infection.
The offspring of these mice had elevated levels of L1 in their brains. In other experiments, they exposed monkeys to a hormone that raises the risk for schizophrenia and they also had increased L1.
This study revealed that in schizophrenia, L1 reinserts into genes involved in synaptic function, the transmission of signals between neurons. This would disrupt the communication between brain cells.
The study raised an intriguing question: Do these jumping genes also play a normal role in the developing brain and in the variety of cognitive skill levels humans and other animals display?