By Alexandra Sifferlin
December 21, 2015

Nonvital transplants

Doctors are performing groundbreaking face transplants, uterus transplants and penis transplants, to name a few. The milestones mark triumphs in transplants that do not save lives but do tremendously improve them.

Fetal DNA testing

Some doctors offer earlier and less invasive screening for genetic abnormalities and even the sex of the fetus. The process involves just a small blood sample, but some experts worry it will introduce more questions than it answers.

Personalized diets

Israeli scientists discovered that people’s bodies respond differently when they eat the same foods, possibly in part because of variations in the microbiome–the trillions of bacteria that live in our gut. That suggests a personalized diet could soon aid weight loss.

Gene editing

A technique called CRISPR-Cas9 allows scientists to theoretically add or remove genetic material, which has great implications for a variety of health problems, especially inheritable diseases. Its co-creator (see page 117) is calling for caution on how it’s used.

Giant data sets

The National Institutes of Health will embark on the most ambitious government-led study to date, collecting data on matters like genetics and lifestyle choices from 1 million Americans over many years.

Contact us at editors@time.com.

This appears in the December 28, 2015 issue of TIME.

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