Rob Stein

Scientists have been tinkering with the DNA in humans and other living things for decades. But one thing has long been considered off-limits: modifying human DNA in any way that could be passed down for generations.

Sperm counts appear to be plummeting throughout the Western world, according to a large study of men around the world.

An international team of scientists analyzed data from nearly 43,000 men in dozens of industrialized countries and found that sperm counts dropped by more than half over nearly four decades.

A new kind of cancer treatment that uses genetically engineered cells from a patient's immune system to attack their cancer easily cleared a crucial hurdle Wednesday.

A Food and Drug Administration advisory committee unanimously recommended that the agency approve this "living drug" approach for children and young adults who are fighting a common form of leukemia. The agency doesn't have to follow the committee's recommendation but usually does.

The U.S. is in the midst of an opioid crisis. Millions of Americans are addicted to the powerful prescription painkillers, and tens of thousands are dying each year from overdoses.

A new report out Thursday offers a bit of hope: Doctors are prescribing opioids less often, and the average dose they're giving patients has dropped, according to the Centers for Disease Control and Prevention.

Advances in technology have made it much easier, faster and less expensive to do whole genome sequencing — to spell out all three billion letters in a person's genetic code. Falling costs have given rise to speculation that it could soon become a routine part of medical care, perhaps as routine as checking your blood pressure.

But will such tests, which can be done for as little as $1,000, prove useful, or needlessly scary?

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