Mother's blood revealed the secret of the fetus

Concerning about dangerous amniocentesis may be a potential risk of miscarriage, a Hong Kong professor has developed a blood test for diagnosing prenatal genetic syndrome through fetal DNA in mother plasma.

The clock that was past midnight a night in the autumn of 1996 was when Yuk Ming Dennis Lo found a breakthrough that promised to change modern medicine. The discovery, for example, is that Lo's treasure is a free-moving DNA in the blood , which can help make prenatal tests for the fetus about genetic syndrome, complete genome creation, and even screening. Cancer at an early stage.

All are in a simple blood test.

Mysterious blood

The fetus' DNA moves freely in the mother 's plasma as Professor Lo's first discovery. This DNA is the window that helps diagnose both present and future fetal health. However, the important finding at the time was not the medical community's interest.

"They thought it was only used for sex selection purposes , " said Professor Lo, who is now director of the Li Ka Shing Health Science Institute in Hong Kong.

Stereotypes suggest that this is just a narrow application and facing moral problems has left scientists missing one of the biggest breakthroughs of the 21st century. However, this difficulty does not prevent Lo from continuing. enthusiastic process.

The beginning of ambition over time

Lo embarked on a search for mother's DNA in her mother's blood at Oxford University, England, where he had the opportunity to meet the leading scientist, Professor John Bell.

"I heard the professor teach about Polymerase chain reaction (PCR) , a technique to amplify a piece of DNA into thousands, even millions of copies. He said this technique will change the world ," said the scientist. 52 years old.

After learning how to perform PCR, Lo quickly rushed to research an effective application for this technique. The destination is a safe and non-invasive test to detect Down syndrome instead of the traditional method of amniocentesis , obstetric procedures that detect abnormalities such as Down syndrome through pregnancy cell screening. pediatric in amniotic fluid.

"A large needle will poke through the mother's abdomen to the uterus , " Lo describes the procedure that could cause miscarriage at an estimated 1% rate, according to the UK National Health Service.

"I wonder why doctors have to perform such dangerous procedures? Why don't we take a blood sample from the mother to check?" He recalled the urge to find a new diagnostic method.

Describe fetal free cell DNA in maternal plasma.(Photo: CNN).

However, scientific knowledge at that time was one step slower than Lo's ambition. In the 1980s when he was a student, experts still believed that the blood of the fetus and the mother was completely independent.

The search for fetal DNA in Dennis Lo's mother's blood lasted for eight years but failed to produce results. The fetus cells go into maternal blood with too little quantity, so the study must be suspended.

The key is from the molecules

1997 was a turning point when Professor Lo returned to Hong Kong. Three months earlier, he learned that cancer patients were found to have DNA from tumors floating in plasma (plasma).

Scientists found that dead cancer cells could release genetic material into the patient's blood, known as free DNA derived from dead tumor cells (ctADN).

"I think a child growing up inside a mother is like cancer growing in the body, except for one thing I've never seen a tumor weigh more than 3.6kg. So, if a small tumor can liberating enough DNA for us to observe, a fetus can do the same thing, " Lo explained.

Consistent with the goal, Lo was forced to find a way to extract DNA from plasma. He suddenly found an exit from a seemingly unrelated category.

"When I was in England, I used to cook instant noodles, boil broth and put noodles in. I suddenly thought the simplest way to deal with plasma was to boil it , " Lo said.

Simple way to bring unexpected effects. When heated, protein in plasma, the component can destroy destroyed DNA, while the DNA needed for the study remains intact.

Following this procedure, Lo began to check the plasma of pregnant women looking for fetal DNA and was completely surprised to see the first result.

"I can't believe my eyes, the long-sought fetal DNA exists in the same part that we missed for the past 8 years."

From discovery to application

Years after the breakthrough DNA discovery, Professor Lo still couldn't find any supporters or applications.

"Discovery will be a great prize if it can become a diagnostic test for Down syndrome, " he recalls advice from experts.

Down syndrome is an inherited disease , which occurs when the fetus mutates a 21st chromosome. Typically, the syndrome is diagnosed by examining the fetal cells and counting the number of chromosomes. Scientists do not believe that free cell DNA can do this. However, Professor Lo proved the opposite.

Over a decade of research, Professor Lo's team discovered that because of a 21st chromosome, the number of molecules produced from this chromosome will increase in mother plasma if pregnant women are carrying fetus with Down syndrome.

"People think we're crazy because this method means having to do a lot of duplicate chain reaction techniques (PCR) , " Lo said.

Fetal DNA in plasma, according to the professor, is very small. Therefore, it is necessary to perform PCR amplification to generate enough data for analysis. The expensive cost at that time made this method unrealistic if applied in bulk. However, fortunate to smile at Professor Lo in 2008 thanks to the introduction of a new generation of DNA sequencing techniques that can generate millions of DNA fragments in a short time.

In 2011, blood tests for Down Syndrome were carried out in mass, so far more than 90 countries have applied it. According to the latest statistics, more than two million pregnant women have used this new noninvasive method in prenatal testing.

Parallel to the undisputed benefit is the issue of sex selection taking advantage of fetal DNA testing. Lo said he was very worried about these moral risks and had developed strict rules prohibiting use for the purpose of sex selection since licensed testing.

Description of blood tests for diagnosis of Down syndrome for the fetus in the womb.(Photo: CNN).

Infinite possibilities

The secret in the blood may contain infinite possibilities in the future, according to Professor Lo. Prenatal genome sequencing is a prerequisite for testing possible future syndromes, including breast cancer due to BRCA1 gene mutations, used in predicting hair color or life expectancy.

The professor noted that the cost was so expensive that these tests could not be made popular today. However, "basically, we opened a non-invasive window to learn about the human body."

Search for cancer

Professor Lo is focusing on studying an adult blood test to diagnose liver, nasal and nasopharyngeal cancer at an early stage that other screening methods cannot detect.

Dubbed the "liquid birth" technique , this method traces the plasma of ctDNA released by cancer cells, thereby determining the type of cancer and the stage in which a person is suffering.

The test has been deployed on 10,000 middle-aged men in Hong Kong and has the potential to save hundreds of thousands of people worldwide if widely used.

Besides, Lo also uses "liquid biopsy" in monitoring rejection reactions when organ transplants and the health of patients after traffic accidents.

Next ambition

Professor Lo set his next goal to be a less invasive DNA test, using maternal urine.

"Two hours after birth, the fetal DNA disappears in her mother's blood. Where did that DNA go? We guess in urine, " the professor said.

He thinks urine may contain another window that opens up the health of the mother and baby in the future.

"Therefore, I think this will be the next 'treasure' that we aim for," he said.