The Delta F508 is the most common CF gene out there. From what I read, it sounds like the G551D is the third most common gene.
I don't think anyone can give you a clear cut answer as to "what they will effect" ... nobody has a crystal ball when it comes to CF. That's part of what's terrible is you just never know for sure what's going to happen until it happens or even if it happens at all -- some people have terrible trouble with their sinuses while others do not, some people are pancreatic sufficient, while others are not, some people have liver & gallbladder problems others do not.... you get the picture.
Generally speaking all CF genes cause a problem with the chloride channels, they are either impaired or not functioning at all -- this is what causes the lungs to hang onto the mucus, which in turn causes the bacteria to settle in and call it home, which causes an infection, which causes the body to send white blood cells to the infection, which die and cause the lung tissue damage..... so what will her CF genes effect???? generally speaking the same as everyone with CF....most likely.... lung and pancreas.
From what I read on one page:
<a target=_blank class=ftalternatingbarlinklarge href="http://ajpcell.physiology.org/cgi/content/full/277/4/C833
">http://ajpcell.physiology.org/...ntent/full/277/4/C833
</a>
the G551D mutation is known for pancreatic sufficiency until a later age -- then it sounds like it may change to pancreatic insufficiency. It also is associated with a lower incidence of meconium ileus, (which usually either happens or doesn't happen at birth, so that is of little use to you now.)
I also learned from another page that the Delta F508 is a class II mutation and the G551D is a class III mutation. There are 5 classes -- one being the most severe and 5 being the least severe (I think). I believe they are classed according to how impaired the channel is. My only other knowledge about classes is the class 4 & 5 are referred to as "mild variant genes".
Hope that helps -- I'm sure there are others on the site with more knowledge, but that's enough to get you started