HITCHHIKER’S THUMB

 

HITCHHIKER’S THUMB

Hitchhiker's thumb is a thumb that's hypermobile, or very flexible, and able to bend backward beyond the normal range of motion. Known formally as distal hyperextensibility, this condition isn’t painful and doesn’t inhibit the thumb’s function in any way.

• People with hitchhiker’s thumb may have acquired two recessive copies, or alleles, of the gene that determines thumb straightness. This means that the trait for hitchhiker’s thumb was present in both parents of the person born with it.
• If instead one parent had the dominant gene for thumb straightness and the other had the recessive gene for hitchhiker’s thumb, their offspring wouldn’t have the condition. People with the recessive gene for this condition are called carriers.
• A person who carries a recessive gene would have to have a child with another carrier of the gene in order for that child to inherit the trait.