What Is The Life Expectancy For Klippel-Feil Syndrome?

What is the average life expectancy for a person with Klippel Feil Syndrome, I have a friend that is 56y/o, she is gradually getting weaker, she has lost all use of her arms, and her legs have been getting weaker over the past several months, she has had increasing falls, and cannot get up by herself as well as she could about 6 months to 1 yr ago.