Background VX-809, a cystic fibrosis transmembrane conductance regulator (CFTR) modulator, has been shown to increase the cell surface density of functional F508del-CFTR in vitro. Methods A randomised, double-blind, placebo-controlled study evaluated the safety, tolerability and pharmacodynamics of VX-809 in adult patients with cystic fibrosis (n=89) who were homozygous for the F508del-CFTR mutation. Subjects were randomised to one of four VX-809 28 day dose groups (25, 50, 100 and 200 mg) or matching placebo. Results The type and incidence of adverse events were similar among VX-809- and placebo-treated subjects. Respiratory events were the most commonly reported and led to discontinuation by one subject in each active treatment arm. Pharmacokinetic data supported a once-daily oral dosing regimen. Pharmacodynamic data suggested that VX-809 improved CFTR function in at least one organ (sweat gland). VX-809 reduced elevated sweat chloride values in a dose-dependent manner (p=0.0013) that was statistically significant in the 100 and 200 mg dose groups. There was no statistically significant improvement in CFTR function in the nasal epithelium as measured by nasal potential difference, nor were there statistically significant changes in lung function or patient-reported outcomes. No maturation of immature F508del-CFTR was detected in the subgroup that provided rectal biopsy specimens. Conclusions In this study, VX-809 had a similar adverse event profile to placebo for 28 days in F508del-CFTR homozygous patients, and demonstrated biological activity with positive impact on CFTR function in the sweat gland. Additional data are needed to determine how improvements detected in CFTR function secondary to VX-809 in the sweat gland relate to those measurable in the respiratory tract and to long-term measures of clinical benefit. Clinical trial number NCT00865904

There is wide agreement on the benefits of NBS for CF in terms of lowered disease severity, decreased burden of care, and reduced costs. Risks are mainly associated with disclosure of carrier status and diagnostic uncertainty. When starting a NBS programme for CF it is important to take precautions in order to minimise avoidable risks and maximise benefits. In Europe more than 25 screening programmes have been developed, with quite marked variation in protocol design. However, given the wide geographic, ethnic, and economic variations, complete harmonisation of protocols is not appropriate. There is little evidence to support the use of IRT alone as a second tier, without involving DNA mutation analysis. However, if IRT/DNA testing does not lead to the desired specificity/sensitivity ratio in a population, a screening programme based on IRT/IRT may be used. Sweat chloride concentration remains the gold standard for discriminating between NBS false and true positives, but age-related changes in sweat chloride should be taken into account. CF phenotypes associated with less severe disease often have intermediate or normal sweat chloride concentrations. Programmes should include arrangements for counselling and management of infants where the diagnosis is not clear-cut. All newborns identified by NBS should be managed according to internationally accepted guidelines. CF centre care and the availability of necessary medication are essential prerequisites before the introduction of NBS programmes. Clear explanation to families of the process of screening and of implications of normal and abnormal results is central to the success of CF NBS programmes. Effective communication is especially important when parents are told that their child is affected or is a carrier. When establishing a NBS programme for CF, attention should be given to ensuring timely and appropriate processing of results, to minimise potential stress for families.

Little is known about the long-term persistence of positive effects induced by a physical conditioning programme in cystic fibrosis. Therefore, this study determined the effects of a 6-month conditioning programme on peak oxygen uptake (primary outcome) and other markers of fitness, physical activity, anthropometry, lung function and quality of life (secondary outcomes), 18 and 24 months after the programme was initiated.Patients with cystic fibrosis aged 12-40 yrs were randomly assigned to an intervention (n523) and a control (n515) group. The intervention group consented to add 3 h of sports per week for o6 months to their previous activities. Controls were asked to maintain their level of activity for 12 months. Patients were seen at baseline and after 3, 6, 12, 18 and 24 months.There was no significant difference between groups at baseline. The intervention induced positive effects on peak oxygen uptake (difference in changes from baseline to the 18-and 24-month assessments between groups: 3.72¡1. ; p,0.05), forced vital capacity (6.06¡2.87% predicted; p,0.05) and perceived health (9.89¡4.72; p,0.05).A home-based partially supervised physical conditioning programme can improve physical fitness, lung function and perceived health long after the intervention has ended.

Cysti c fi br osi s (CF), the most common sever e autosomal r ecessi ve tr ai t among Caucasi ans, i s caused by mol ecul ar l esi ons i n the cysti c fi br osi s tr ansmembr ane conductance r egul ator gene (CFTR). The cour se of the mul ti -or gan di sease CF i s hi ghl y var i abl e, suggesti ng the i nfl uence of envi r onmental factor s and/or modul ati ng genes other than CFTR on the di sease phenotype. To evaluate the cause of CF disease variability, the European CF Twin and Sibling Study col l ected data on tw o cl i ni cal par ameter s most sensi ti ve for the cour se and pr ognosi s of CF, i e w ei ght pr edi cted for hei ght (w fh)% (r epr esentati ve for the nutr i ti onal status) and FEVPer c (r epr esentati ve for the pul monar y status) for a cohor t of 277 si bl i ng pai r s, 12 pai r s of di zygous tw i ns and 29 pai r s of monozygous tw i ns. Of these 318 CF tw i n and si b pai r s, 114 w er e r epor ted to be homozygous for the most fr equent CF di sease-causi ng l esi on, ∆F508. I ntr a-pai r di scor dance w as assessed by the i ntr a-pai r di ffer ences w i th w fh% and FEVPer c and by DELTA , a composi te par ameter defi ned by l i near combi nati on of w fh% and FEVPer c i n or der to descr i be di scor dance w i th r espect to the overall disease severity. Monozygous twins had a significantly lower DELTA than dizygous twins (P = 0.05) i ndi cati ng that CF di sease sever i ty i s modul ated by an i nher i ted component i n addi ti on to the CFTR gene i tsel f. Extr eme phenotypes ar e consi der ed to be mor e i nfor mati ve for the anal ysi s of any quanti tati ve tr ai t. Thus, w e ai med to quanti fy di sease sever i ty and i ntr a-pai r di scor dance i n or der to sel ect pai r s w i th the extr eme phenotypes DI S (di scor dant pati ent pai r s), CON + (concor dant and mi l dy affected pati ent pai r s) and CON -(concor dant and sever el y affected pati ent pairs). The algorithm reliably discriminated between pairs DIS, CON + and CON -among the cohor t of ∆F508 homozygotes. The sel ected pai r s fr om these categor i es demonstr ated non-over l appi ng pr oper ti es for w fh%, FEVPer c and the i ntr a-pai r di ffer ence of both par ameter s. Twin Research (2000) 3, 277-293. Keyw or ds: cysti c fi brosi s di sease severi ty, affected rel ati ve pai r, tw i n and si bl i ng study, extreme phenotypes, al gori thm based sel ecti on I ntr oducti on Cysti c fi brosi s (CF) i s know n as the most common severe autosomal recessi ve di sease w i thi n the Caucasi an popul ati on, exhi bi ti ng an i nci dence of 1 i n 2500 bi rths.1 The symptoms of the di sorder are caused by an i mpai red functi on of exocri ne gl ands i n many organs, but major mani festati ons i nvol ve the respi ratory and the gastroi ntesti nal tracts.1 The di sease i s caused by mutati ons i n both chromosomal copi es of the cysti c fi brosi s transmembrane conductance regul ator (CFTR) gene. 2 The course of CF i s hi ghl y vari abl e w hen compari ng unrel ated pati ents w i th i denti cal CFTR mutati on genotypes, 3,4 o...