kylie mcpeak is 6. she was also selected to come to the udp. >> she knows she's different, but it doesn't seem to faze her. she kind of seems like she's just like a normal kid. >> reporter: how serious is kylie? >> well, she's, i would say real serious. i think that she has a disorder that will threaten her life. it is essentially the issue here. we're sort of racing against time. >> reporter: the undiagnosed diseases program was launched only two years ago at nih. it accepts only the rarest of medical cases. >> this is saying, when you hear hoof beats, think of horses not zebras and i say but if you hear horse beats in africa or the nih, it's probably a zebra. >> reporter: it's not only about saving lives. here they're also hoping to discover new diseases and create new science. >> it's really sort of the inspiration that we all have as clinical researchers. >> reporter: in two years, the udp has had more than 3,000 inquiries. >> this is an accept ansz letter. >> reporter: udp has accepted a little ove