The genetic code to alllife on Earth, both simple and complex, comes down to four basic letters: A, C,T and G.

Untangling the role thatthese letters play in lifes blueprint has allowed scientists to understandwhat makes everything from bacteria to people the way they are. But as researchershave learned more, they have also sought ways to tinker with this blueprint,bringing ethical dilemmas into the spotlight. The Gene, a two-part PBS documentary from executive producer Ken Burnsairing April 7 and 14, explores the benefits and risks that come withdeciphering lifes code.

The film begins with oneof those ethical challenges. The opening moments describe how biophysicist HeJiankui used the gene-editing tool CRISPR/Cas9 to alter the embryos of twin girls who were born in China in 2018 (SN: 12/17/18). Worldwide, criticscondemned the move, claiming it was irresponsible to change the girls DNA, asexperts dont yet fully understand the consequences.

This moment heraldedthe arrival of a new era, narrator David Costabile says. An era in whichhumans are no longer at the mercy of their genes, but can control and evenchange them.

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The story sets the stagefor a prominent theme throughout the documentary: While genetics holdsincredible potential to improve the lives of people with genetic diseases,there are always those who will push science to its ethical limits. But thedriving force in the film is the inquisitive nature of the scientistsdetermined to uncover what makes us human.

The Gene, based on the book of the same name by Siddhartha Mukherjee (SN:12/18/16), one of the documentarys executive producers, highlights many ofthe most famous discoveries in genetics. The film chronicles Gregor Mendels classicpea experiments describing inheritance and how experts ultimately revealed inthe 1940s that DNA a so-called stupid molecule composed of just four chemicalbases, adenine (A), thymine (T),cytosine (C) and guanine (G) is responsible for storing geneticinformation. Historical footage, inBurns typical style, brings to life stories describing the discovery of DNAshelical structure in the 1950s and the success of the Human Genome Project indecoding the human genetic blueprint in 2003.

The film also touches ona few of the ethical violations that came from these discoveries. The eugenicsmovement in both Nazi Germany and the United States in the early 20th century aswell as the story of the first person to die in a clinical trial for genetherapy, in 1999, cast a morbid shadow on the narrative.

Interwoven into thistimeline are personal stories from people who suffer from genetic diseases.These vignettes help viewers grasp the hope new advances can give patients asexperts continue to wrangle with DNA in efforts to make those cures.

In the documentarysfirst installment, which focuses on the early days of genetics, viewers meet a family whose daughter is grappling with arare genetic mutation that causes her nerve cells to die. The family searchesfor a cure alongside geneticist Wendy Chung of Columbia University. The secondpart follows efforts to master the human genome and focuses on AudreyWinkelsas, a molecular biologist at the National Institutes of Health studyingspinal muscular atrophy, a disease she herself has, and a family fighting tosave their son from a severe form of the condition.

For science-interested viewers, the documentary does not disappoint. The Gene covers what seems to be every angle of genetics history from the ancient belief that sperm absorbed mystical vapors to pass traits down to offspring to the discovery of DNAs structure to modern gene editing. But the stories of the scientists and patients invested in overcoming diseases like Huntingtons and cancer make the film all the more captivating.

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The PBS documentary The Gene showcases genetics promise and pitfalls - Science News