My nephew has been quite sick lately. He has had upper respiratory infections twice this year, so the doctor ordered a cystic fibrosis mutation analysis. I need help understanding the results. Results: Positive for one copy of the L206W mutation, one CF mutation has been identified in this individual. The presence of a second mutation, which would confirm a diagnosis of CF, cannot be ruled out. Please help me understand this. Thank you, RP <img src="i/expressions/face-icon-small-confused.gif" border="0">