What you're describing does NOT define transhumanism! You should do more research, because transgender surgeries, where doctors remove healthy body parts and organs to allow humans to choose what gender they desire to be is the first step in transhumanism.
Transgender surgery is a way of transitioning into transhumanism. What is achieved when you remove a young girls' healthy breasts and female organs to help her transition into a boy? She never becomes a boy, because her DNA defines her as a girl. So she is no longer identified as a girl, but neither is she identified as a boy! She cannot be a sister, but neither a brother, she cannot be a mother, but neither can she be a father. And she can never be a wife, or husband no matter how many times we're told she can be. This human being has lost their God given identity. Which is exactly what transhumanists pushing transgender desires to accomplish.
Now the transhumanist can be the savior for this person without identity by promising a way of returning identity to them by tinkering with their God given DNA. A person having no identity, feeling desperate to belong can be sold just about anything.
DNA is given by God and is uniquely designed without duplication. Transhumanists have no idea how humans might be affected by combining their DNA with technology. Yet they gleefully proclaim they can make man better. Because they don't believe in God, nor that man was created in the likeness and image of God. So why not experiment on humankind? Perhaps, so they think, they can so improve humankind that through transhumanism man can finally attain immortal life without Christ.