Scientists have discovered that a particular gene variation contributes to the birth weight of babies. The gene variant is one that is passed down from the mother or from the maternal grandmother. This is why it is being referred to as the “Grandmother Gene”.
The size of an infant, when he or she is born, is noteworthy. Hospitals will write down the height, and the weight, of a baby in medical paperwork. News websites and television stations often have stories about babies who were born extremely small, or who were born at a much larger size than the average. New parents get asked a lot of questions after a baby is born, and one of the typical questions includes an inquiry about how big the baby was at birth.
Researchers led by Professor Gudrun Moore of University College London studied a gene called PHLDA2. They looked at this gene in almost 9,500 DNA samples that were taken from both mothers and their babies. The samples were collected in three separate studies.
They found a gene variant on the PHLDA2 gene. The variant is called RS1. The researchers found that the RS1 variant seemed to change the way in which the PHLDA2 gene functioned. This led to higher birth weights. Previous studies showed that the PHLDA2 gene had a profound effect on birth weight, because it acted as a growth suppressor.
Researchers found that if the genetic variant of the PHLDA2 gene was inherited from the mother, it results in causing the baby to be, (on average), 93 grams bigger. If the gene was, instead, inherited from the mother’s mother, (in other words, the infant’s maternal grandmother), it results in causing the baby to be born as much as 155 grams bigger, (on average).
The RS1 variation was found in about 13% of the samples in the study. Around 87% of the individuals in the study had a different variation, called RS2. The RS2 variation is only found in humans.
It is believed that the RS2 variation, (which is much more common than the RS1 variation), was intended to produce a smaller baby. That function would have started as a protective measure to enhance the potential of the mother surviving childbirth.
Image by ECohen on Flickr