BGI has analyzed the world’s largest set of genome data from pregnant women, a total of 141,431 expectant mothers from across China. The results from the study were published in Cell.

The genomic analyses from non-invasive prenatal testing (NIPT) revealed new genetic associations, patterns of viral infections, and history in Chinese populations. The study is the largest genomic study of the Chinese population to date and represents the first phase of BGI's Million Chinese Genome Project.

The research has revealed novel genetic associations between genes and pregnancy-related traits, including the birth of twins and the woman’s age at pregnancy, one of the well-known measurements of fertility. The analysis also allowed researchers to reconstruct the recent movement and intermarriage of different ethnic groups in China, and promises to help identify genes that make people susceptible to viral infection.

“For the first time, we proved that NIPT data can be used in genome-wide association studies to understand the genetic architecture of complex traits and disease,” said Siyang Liu, senior research scientist in BGI and first author of the study, in a press release.  “This brings up a new and promising model of investigating genetic mechanisms underlying traits related to maternal and child’s health.”

The data used in the study were from 141,431 anonymized and consented pregnant women participants, who took non-invasive prenatal genetic tests. The mothers-to-be had provided blood samples to be tested for fetal chromosomal abnormalities, primarily Down syndrome, which is possible because mothers have DNA from their unborn child in their bloodstream.

The participants came from all the 31 provincial administrative units in mainland China and included not only Han Chinese but also 36 ethnic minorities. The large sampling, about 1/10,000 of the Chinese population, is a good representation of the entire population.

The researchers sequenced, on average, only about 10% of each mother’s genome, relying on large numbers of genomes to leverage individual sequencing data to discover new genetic links.

“Sufficient large sample size is of fundamental importance in resolving biological questions in population and medical genetics,” the researchers wrote. “Given a fixed budget, sample size tends to play a more essential role compared to sequencing depth.”

The availability of the large sample size was crucial, the researchers discussed, saying that the ability to analyze samples of “shotgun DNA sequencing” from blood opens up new avenues for investigating hypotheses regarding interactions between viruses and host DNA genetic variability.

“As NIPT testing expands to millions of individuals globally, obtaining informed consent for patients and effective digital curation of medical records should be prioritized by the medical community,” they wrote.