More than 13 million children have been born worldwide through assisted reproduction. Could first days of life in laboratory leave trace in their DNA? Scientists in China looked for one possible sign and found difference in genome’s so-called ‘jumping genes’.
Previous research has suggested some health conditions may be slightly more commonamong children conceived through in vitro fertilization IVF. Finding out why is difficult. Any effects of treatment must be separated from factors such as parents’ health and what happens during pregnancy. Researchers at Sun Yat-sen University turned attention to pieces of DNA known as jumping genes.
Despite name, they are not ordinary genes. Some can make copies of themselves and insert those copies into new parts of our DNA. Type examined in this study is called LINE-1. Earlier study in mice had found experiences early in life could affect jumping genes in brain. What happens in mice, though, cannot tell us what happens to human embryo during IVF.
33 IVF vs 42 Natural Conception Children Compared
To look for difference, team examined blood samples from 33 children conceived through IVF and 42 conceived without fertility
treatment. Most samples collected from umbilical cords at birth. Some came from children aged two to five. Children conceived through IVF had slightly higher amount of LINE-1 DNA overall. Team also checked whether result depended on type of fertility treatment. Some children had been conceived through conventional IVF, while others were conceived through procedure in which single sperm is injected into egg – known as ICSI.
Researchers found no clear difference in LINE-1 amounts between those two groups. Researchers had another way to explore it . In three families , they could compare child conceived through IVF with brother or sister conceived without fertility treatment.
IVF-conceived child had more LINE-1 DNA in all three families . But three families are too few to establish that difference is due to IVF. When they separated children by sex, difference was clearer among girls. Boys showed similar trend, but result was less certain.
Researchers say larger group needed to find out whether distinction holds up.
LINE-1 Spots Near Heart, Metabolism, Brain, Cancer Genes
When team looked more closely at children’s DNA, they found that at some spots, LINE-1 sequences were detected more or less often in one group than other. Some of those spots lay within wide stretch of DNA around genes previously linked to heart, metabolism, brain, and cancer.
Could that help explain health differences reported in earlier research? Perhaps, but this study cannot answer that question yet. Team did not measure whether those genes behaved differently, and did not follow children to see whether any became ill. For now, connection gives scientists somewhere specific to look next.
Researchers also cannot say exactly when difference arose. They read children’s DNA from blood samples; they did not watch jumping genes move in embryos. Without DNA from both parents , they cannot tell whether particular changes appeared in children or were passed down through family. Other experiences during pregnancy may also have played part.
Larger Nature Medicine Study Of 8,328 Babies Context
Separate, much larger study published in Nature Medicine compared DNA of 8,328 babies with that of their parents. It found links between particular fertility treatment steps and new DNA changes, some arising early in development.
That study examined different kind of change, so it does not confirm new finding, but it’s yet more evidence that assisted reproduction may leave mark. In terms of Chinese research , team has uncovered pattern that may help scientists ask more precise questions about IVF and early development. Next step is to see whether it appears again in larger groups of families, where it comes from, and whether it makes any difference to children’s health.
Research published in American Journal of Obstetrics & Gynecology.
Q&A
Q: Do IVF babies have different jumping genes LINE-1?
A: Sun Yat-sen University study of 33 IVF and 42 non-IVF children found slightly higher amount of LINE-1 DNA overall in IVF group , mostly from umbilical cord blood at birth and some ages 2-5 ; no clear difference between conventional IVF and single-sperm injection ICSI.
Q: Is LINE-1 difference clearer in girls or boys?
A: Difference clearer among girls in sex-separated analysis ; boys showed similar trend but less certain; researchers say larger group needed; in 3 families with sibling comparison IVF child had more LINE-1 in all three but too few to prove IVF cause.
Q: Does hidden DNA signature mean IVF babies will have health problems?
A: No proof yet; study did not measure gene behavior or follow illness; some LINE-1 spots lay near genes previously linked to heart metabolism brain cancer, but connection only gives specific place to look next; needs larger family studies.
FAQ
1. How many IVF children born worldwide?
More than 13 million children born through assisted reproduction globally, per study background.
2. What are jumping genes LINE-1?
Not ordinary genes; some make copies and insert into new DNA parts; type examined LINE-1 ; earlier mouse study suggested early life experiences could affect them in brain, but mouse cannot tell human IVF embryo outcome.
3. Where was study published?
Published in American Journal of Obstetrics & Gynecology by team at Sun Yat-sen University China.
4. How does this compare to 8,328 baby study?
Much larger Nature Medicine study of 8,328 babies vs parents found links between
fertility treatment steps and new DNA changes arising early, but examined different kind of change so does not confirm LINE-1 finding , yet adds evidence assisted reproduction may leave mark.
5. What are limitations of Chinese study?
Small sample 33 vs 42, no parental DNA to tell if changes inherited or new, did not watch jumping genes move in embryos, did not measure gene function or child health outcomes, other pregnancy experiences may play part, sibling comparison only 3 families.
Disclaimer: This article for informational purposes only and does not constitute medical advice.
