She has her mother's laugh - Carl Zimmer

A great read on the history of our understanding of Genes and factors affecting heredity.

Carl Zimmer packs the book with numerous anecdotes to keep you hooked.

Even for me, who quit on biology in school, the first 300 odd pages were a breeze. The next 300 was slightly more difficult, as the terms used were not familiar to me. 

But a delightful read throughout anyway

Do human races differ much genetically? Is there much in common, genetically speaking between an Asian, African and a European?

The author makes it very clear that though physical differences may appear amongst races on a superficial level to be very dramatic, they are determined by only a minute portion of the genome: we as a species have been estimated to share 99.9% of our DNA with each other. The few differences that do exist reflect differences in environments and external factors, not core biology.

And for that hotly debated issue- Is intelligence all genes? Well- partly says the author. It's genes and the environment that shape who we are.

And even though height is even more easily measurable than intelligence, scientists have still not been able to identify the genes that is responsible for it.

But height has also much to do with better food and health care systems. For instance South Koreans are more than an inch taller in comparison to North Koreans, which is a clear demonstration of how environment factors matter.  

Heredity is not just genes by the way. We inherit culture too! And most of us have traces of  Neanderthal genes in us.

One of the more heart warming stories in the book is on the treatment of  PKU or Phenylketonuria, a genetically determined metabolic disorder. Babies with PKU, if left untreated will have devastating brain damage.  

PKU is an inherited disease in which the body cannot metabolize an amino acid called phenylalanine. Normally phenylalanine is metabolized and converted into tyrosine, another amino acid, but if it stays as phenylalanine, there will be too much of it, and high levels of phenylalanine are harmful to the brain.

PKU was diagnosed as early as 1934. But scientists/doctors could not find a cure for it.

It all changed on account of one persistent mother, Mary Jones.

The journey to a treatment started in 1949, when a British woman named Mary Jones brought her seventeen-month-old daughter, Sheila, to a Birmingham hospital. Sheila couldn't stand or even sit up. Nor did she take an interest in her surroundings.

A doctor at the hospital named Horst Bickel examined Sheila and informed Jones that she had PKU. "Her mother was not at all impressed when I showed her proudly my beautiful раper chromatogram with the very strong phenylalanine (Phe) spot in the urine of her daughter proving the diagnosis," Bickel later recalled.

Jones wanted to know what Bickel was going to do now that he had discovered Sheila's disease. There was nothing to do,Bickel explained.

Jones rejected his answer. She came back the next morning to demand help. When he turned her down,she came back every morning.

She was very upset and did not accept the fact that at the time no treatment was known for PKU," Bickel said. "Couldn't I find one?".........

Jones was so insistent, though, that Bickel decided to talk to some of his colleagues about a diet for PKU. He learned that a biochemist in London named Louis Wolff had tried concocting a broth that could provide protein to people with PKU without poisoning them with phenylalanine. When he proposed feeding his broth to patients, his superiors at Great Ormond Street Hospital told him his job did not involve crazy treatments for the incurable.

Wolff gave his recipe to Bickel, who followed the directions, working in a frigid lab kept cold to prevent the concoction from spoiling.

Eventually, Bickel prepared enough of the stuff for Sheila. He instructed Jones that the girl was to eat nothing else. To his delight, the phenylalanine in Sheila's bloodstream dropped......

The diet even showed signs of improving her brain. Within a few months she began to sit up, then to stand, then to walk with assistance. Her musty odor even disappeared.

But when Bickel told his colleagues at the hospital, they scoffed. They were sure Sheila had improved merely thanks to the extra attention she was getting.

Bickel decided there was only one way to persuade them: take Sheila off of the diet.

Without telling Jones, Bickel secretly added phenylalanine to the formula. Within a day on the altered diet, Sheila started deteriorating. Soon she stopped smiling, making eye contact, or even walking. Bickel and his coworkers told  Jones of their secret maneuver, and put her back on the low-phenylalanine formula. While the transformation was enough proof for Bickel, he didn't think it would be enough to persuade skeptical colleagues. He got Jones's permission to bring Sheila into the hospital and feed her Phenylalanine again.

This time, Bickel .... captured his diet treatment to Sheila Jones in a movie. The movie is available on YouTube and a great watch.

https://www.youtube.com/watch?v=OqZ7QHO5_hs

Bickel's movie was impressive enough to change the minds of doctors at Great Ormond Street.

The treatment for PKU started. By the 1970s, the first generation of people treated for PKU since birth reached adulthood. They could finish school, hold jobs, have ordinary lives.

 In 2001,a graduate student named Tracy Beck became the first person with PKU to gain a PhD. She became an astronomer, helping to build the James Webb Space Telescope. For thousands of years, people who inherited the mutations in Beck's PAH genes would have looked to the sky and not known the word for the lights they saw. Now Beck was helping to extend humanity's gaze to the farthest edges of the universe.

 Sadly for Mary Jones, life wasn't fair on her. Suffering from mental illness herself, Mary Jones, a single mother, ended up in an institution. Sheila Jones learned to feed and dress herself, but could never learn to speak.

Sheila Jones has however been immortalised by the institution of an award in her name- The Sheila Jones Award in 2017. It is an award for patient advocates. This can be awarded to individuals, groups or organizations.

Epigenetics

A current fascinating field of study is epigenetics.   Epigenetics suggests that it possible for your experience to produce changes in your genes that could then be inherited by your children.  It opens up the possibility of a heredity of experience. 

It is being suggested that certain experiences — child neglect, drug abuse or other severe stresses — could set off epigenetic changes to the DNA inside the neurons of a person’s brain.

Jews, whose great-grandparents were chased from their Russian shtetls; Chinese whose grandparents lived through the ravages of the Cultural Revolution; adults of every ethnicity who grew up with alcoholic or abusive parents — all carry with them more than just memories. 

Our experiences, and those of our forebears, are never gone, even if they have been forgotten. The DNA remains the same, but psychological and behavioral tendencies are inherited. You might have inherited not just your grandmother’s knobby knees, but also her predisposition toward depression caused by the neglect she suffered as a newborn. Or for that matter if your grandmother was adopted by nurturing parents, you might be enjoying the boost she received thanks to their love and support.

Epigenetics, can be seen in plants: where what they experience affects future generations, many generations down. There's pretty good evidence in some animals like worms. But when we get closer to ourselves in mammals like rats, it gets more debatable. When we get to humans, a lot of researchers argue that they're isn’t really compelling data yet for it. 

Still a topic of debate and who know what the future holds?

CRISPR

However one of the biggest science stories of recent times is CRISPR (stands for Clustered Regularly Interspaced Short Palindromic Repeats)

CRISPR is basically a group of molecules that can edit DNA. You can fine tune the CRISPR molecules to go after any piece of DNA you want. They can cut that DNA and then you can actually insert a different piece of DNA in its place. 

So this could allow you for example to fix a defective gene. If somebody has cystic fibrosis for example, in theory you could use CRISPR to repair the gene that's faulty in them and then they would not suffer from cystic fibrosis any longer. And also against things like cancer because you can actually take people's own immune cells and edit their genes so that they can recognize and attack cancer cells.

Some scientists have repaired defective DNA in mice, for example, curing them of genetic disorders. Plant scientists have used CRISPR to edit genes in crops, raising hopes that they can engineer a better food supply. Some researchers are trying to rewrite the genomes of elephants, with the ultimate goal of re-creating a woolly mammoth. 

The days when CRISPR technology will be used to alter the genes of human embryos does not seem far off.

 There is at present a  self-imposed moratorium in the United States and Europe to work on human embryos. Not  in China though.  Reports suggest that researchers in China have actually proceeded to human clinical trials using CRISPR.

With CRISPR, it is easy to imagine a world where the haves and have-nots diverge even further in health outcomes than they already do — at the genetic level, because rich people can afford to enhance their genes and their yet-unborn kids’ genes for intelligence, musical ability, height etc.

So assuming we can figure out how to genetically engineer smarter, stronger sons and daughters, who is going to stop us?

 The book covers much more fascinating aspects on genes and heredity, and is definitely a recommended read.