• Question: Hello Stephane! I have another question for you: why do some babies have to have an operation to cut off limbs when they have two healthy parents? Where would those genetics come from? Thanks!

    Asked by AnimalLover to Stéphane on 13 Mar 2018.
    • Photo: Stéphane Berneau

      Stéphane Berneau answered on 13 Mar 2018:

      It can be genetic.

      During embryo development, there is a specific family of genes that are responsible for the structure and location of body part: HOMEOBOX genes.
      These genes are very well conserved between species.
      However, abnormalities can happen due to a mutation or the protein regulated by the homeobox genes expression does not respond.
      Bardet-Biedl syndrome (BBS) is a genetic condition that impacts multiple body systems. People suffering from this syndrome tend to have an extra digit on their hands and/or feet.

      Missing a body part can also be linked to lifestyle and medication. Thalidomide is a medication that was prescribed for certain types of cancers and was authorized for pregnant women. Complications were observed at birth, children were born with deformities of all four limbs. It was a big scandal.

      Moreover, there is another possibility for having another set of limbs. The extra set of limbs can come from their twin… During early embryo development, one of the twin embryos will “swallow”/absorb the other embryo leading to being a chimeric person.

      Video about twin syndrome:

Comments