There have been several references to what double f508 means recently, so I searched for threads dealing with it and have included these links below. Hopefully they help some, I scanned for dealing wtih double delta f508 rather than content.
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=4121&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="https://http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=10226&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=1175&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=6&threadid=7608&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=4824&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=6&threadid=3978&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=2490&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=6&threadid=1802&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=4121&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="https://http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=10226&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=1175&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=6&threadid=7608&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=4824&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=6&threadid=3978&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=5&threadid=2490&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://forums.cysticfibrosis.com/messageview.cfm?catid=6&threadid=1802&highlight_key=y&keyword1=double%20delta%20f508">http://forums.cysticfibrosis.c...=double%20delta%20f508</a>