Table 3 Assessment of basic defect (B): intestinal current measurements (ICM)
Patient numberCFTR genotypeCarbachol (% reverse signal)Response toInterpretation
cAMPDIDS + histamine (% rev. signal)Residual chloride conductanceSensitivity to DIDScAMP response
Out-of-frame deletion
1CFTRdele2,3(21 kb)/CFTRdele2,3(21 kb)100None100NoNoNo
Nonsense mutation
2R553X/R553X100None100NoNoNo
3R1162X/R1162X0Yes40YesYesYes
4R1162X/R1162X45Yes90YesYesYes
Splice-site mutation
51898+3 A-G/1898+3 A-G0Intermediate0YesNoYes
63849+10 kb C-T/3849+10 kb C-T70Minute70YesNoYes
73849+10 kb C-T/3849+10 kb C-T100Minute100MinuteNoYes
In-frame deletion
8CFTRdele2(ins186)/CFTRdele2(ins186)100Small100SmallYes†Yes
9CFTRdele2(ins186)/CFTRdele2(ins186)100None100NoNoNo
10CFTRdele2(ins186)/CFTRdele2(ins186)40Small40YesNoYes
Missense mutation
11E92K/E92K40Small50YesNoYes
12G314E/G314E0Intermediate0YesNoYes
13L997F/L997F0Normal0YesNoYes
14W1098L/W1098L40Small40YesNoYes
15M1101K/M1101K30Intermediate70YesYesYes
16M1101K/M1101K0Intermediate30YesYesYes
17M1101K/M1101K50Small100YesYesYes
Non-CF*0Normal0YesNoYes
>20 μA/cm2>20 μA/cm2>20 μA/cm2
CF*0–100None/small0–100Yes or noYes or noYes or no
(All patients)<10 μA/cm2<5 μA/cm2<10 μA/cm2
Subgroups:
CF*90–100None90–100NoNoNo
(no residual chloride secretion)<0 μA/cm2<1 μA/cm2<0 μA/cm2
CF*0–90Small0–90YesNoYes
(residual chloride secretion)0–10 μA/cm2<5 μA/cm20–10 μA/cm2
CF*0–100None/small</p>100YesYesYes or no
(alternative chloride secretion)<10 μA/cm2<5 μA/cm2<0 μA/cm2
  • *Range and threshold of values for the different categories are based on previously published data (summarised in De Jonge et al4).

  • †cAMP response sensitive to DIDS in patient 8.