epigenetic changes with alterations in the structure of the DNA and its associated proteins, histones, which affects the way that genes can behave in later life.

subsequently began producing the enzyme

proved so much they no longer met the criteria for legal blindness

injected the functional genes into the previously untreated eye

improved as soon as two weeks after the operation: They could navigate an obstacle course, even in dim light, avoiding objects that had tripped them up before, as well as recognize people's faces and read large signs

brains were much more responsive to optical input as well.

second round of gene therapy further strengthened the brain's response to the initially treated eye as well as the newly treated one

that neuroplasticity plays a role

visual cortex responding to the newly flowing channel of information from the second eye bolster activity in areas of the visual cortex responding to the initially treated eye.

67 percent more neurons in their prefrontal cortex (PFC) than typical children

executive functions"—high-level thinking, such as planning ahead, inhibiting impulses and directing attention.

In brain tissue from both autistic children and autistic adults, genes coding for proteins that identify and repair mistakes in DNA were expressed at unusually low levels. Additionally, all autistic brains demonstrated unusual activity levels for genes that determine when neurons grow and die and how newborn neurons migrate during early development

Some genes involved in immune responses, cell-to-cell communication and tissue repair, however, were expressed at unusual levels in adult autistic brains, but not in autistic children's brains

Errors accumulate.

autistic child develops in the womb, something—an inherited mutation or an environmental factor like a virus, toxin or hormone—muffles the expression of genes coding for proteins that usually fix mistakes in sequences of DNA

The genetic systems controlling the growth of new neurons go haywire, and brain cells divide much more frequently than usual, accounting for the excess neurons found in the PFC of autistic children.

autistic brain grow physically larger and form more connections than in a typical child's brain.

immune system reacts against the brain's overzealous growth,

Not all researchers, however, accept

If scientists definitively link autism to a characteristic sequence of changes in gene expression and unusual neural growth, then it becomes possible to target and reverse any one of the thousands of steps in that sequence.

genetic adaptation for high production of Omega-3 and Omega-6 fatty acids is found only in humans

300 000 years ago in the evolutionary line that led to modern humans

important factor for human survival in environments with limited dietary access to fatty acids

In today’s life situation, with a surplus of nourishment, this genetic adaptation contributes instead to a greater risk of developing disorders like cardiovascular disease

first study to show a genetic adaptation of human fat metabolism

thrifty gene

adaptation that contributed to enhanced survival in an earlier stage of human development, but in a life situation with an excess of food instead constitutes a risk factor for lifestyle diseases