Mark Zuckerberg, the co-founder of Facebook, and his wife, the pediatrician Priscilla Chan, announced plans last month to spend $3 billion over the next decade fighting diseases. Mr. Zuckerberg and Dr. Chan said they hoped their project — including a $600-million investment in the Biohub, a new physical lab space for universities in the Bay Area — would help scientists and engineers cure, prevent, or manage all diseases by the end of the century.