Explore the vast range of titles available.

Garry Cutting and colleagues report a comprehensive functional and clinical analysis of CFTR variants reported in cystic fibrosis. They determine that 128 of 160 CFTR variants with an allele frequency of >0.01% are causal for disease. Allelic heterogeneity in disease-causing genes presents a substantial challenge to the translation of genomic variation into clinical practice. Few of the almost 2,000 variants in the cystic fibrosis transmembrane conductance regulator gene CFTR have empirical evidence that they cause cystic fibrosis. To address this gap, we collected both genotype and phenotype data for 39,696 individuals with cystic fibrosis in registries and clinics in North America and Europe. In these individuals, 159 CFTR variants had an allele frequency of ł0.01%. These variants were evaluated for both clinical severity and functional consequence, with 127 (80%) meeting both clinical and functional criteria consistent with disease. Assessment of disease penetrance in 2,188 fathers of individuals with cystic fibrosis enabled assignment of 12 of the remaining 32 variants as neutral, whereas the other 20 variants remained of indeterminate effect. This study illustrates that sourcing data directly from well-phenotyped subjects can address the gap in our ability to interpret clinically relevant genomic variation.

It is well known that among patients with cystic fibrosis who have the ΔF508 deletion mutation, there is substantial variation in the severity of clinical disease. These investigators identified, and then replicated in a second population, variants in the DNA encoding of the TGFβ1 gene that were associated with more severe disease. These investigators identified, and then replicated in a second population, variants in the DNA encoding of the TGFβ1 gene that were associated with more severe disease. Cystic fibrosis is a recessive genetic disorder that reflects mutations in the cystic fibrosis transmembrane conductance regulator ( CFTR ) gene. 1 Classic cystic fibrosis reflects two loss-of-function alleles, whereas nonclassic cystic fibrosis is characterized by at least one mutant CFTR allele that confers partial function and, in most cases, better survival. There is great variability of pulmonary phenotype and survival in cystic fibrosis, even among patients who are homozygous for the most prevalent mutation, ΔF508. 1 , 2 Although environmental influences may modify clinical disease, there is probably additional genetic variation (i.e., the presence of “modifier” genes 3 ) that contributes to the . . .

The objectives of this study were to determine the prevalence of morphometric vertebral fractures in a large cohort of adult cystic fibrosis (CF) patients, and to examine the association between fractures and bone mineral density (BMD). Cross-sectional retrospective study. A tertiary care academic hospital. Adult CF patients who had undergone BMD testing and chest radiography within 1 month of each other. BMD was measured by dual-energy x-ray absorptiometry (DXA) at the lumbar spine (LS) and femoral neck (FN). Vertebral fractures were diagnosed using lateral chest radiographs. Several clinical and biochemical variables were assessed as correlates. Sixty subjects (36%) had z scores between −1.0 and −2.5, and 15 subjects (9%) had z scores of < −2.5. Twelve patients (7.2%) had 19 morphometric fractures. The mean BMD at the LS was 1.266 g/cm2 in the fracture group and 1.112 g/cm2 in the nonfracture group (p = 0.0002). The mean BMD at the FN was 1.129 g/cm2 in the fracture group and 0.987 g/cm2 in the nonfracture group (p = 0.0006). Both FEV1 and body mass index were significantly associated with BMD at both the LS and the FN. Seven percent of adult patients with CF had vertebral fractures as determined by morphometry. Subjects in the fracture group had both clinically and statistically higher BMD as measured by DXA. Our findings raise the intriguing possibility that BMD may not be useful in identifying CF patients with fractures.

Children with complex heart defects are sedentary, with activity level unrelated to exercise capacity. We sought to identify factors associated with physical activity level for children who have the Fontan procedure. We used a cross-sectional study, 64 children (25 female, 5-11 years) after Fontan. Measurements were weekly minutes of moderate-to-vigorous physical activity, cardiac status, resting/exercise cardiopulmonary capacity, gross motor skill, health-related endurance/strength/body composition, and parent/child activity perceptions. Participants performed 361 ± 137 minutes per week of moderate-to-vigorous physical activity. Increased activity related to antithrombotic medication use (86 min/wk), lower resting heart rate (3 min/wk), higher weekday outdoor time (0.7 minutes per outside minute), lower family income (13 minutes per $10,000), and higher parent rating of child's activity relative to peers (36 min/wk). Factors related to decreased activity were winter season (−84 min/wk), history of arrhythmia (−96 min/wk), and greater child confidence in own ability to be active (−113 min/wk). Physical activity after the Fontan procedure is primarily associated with factors unrelated to cardiac status. Interventions that impact these modifiable factors would be expected to enable these children to achieve the recommended activity levels associated with optimal health.

To define the clinical characteristics and diagnostic parameters of patients with cystic fibrosis (CF) diagnosed in adulthood. Retrospective cohort study. Tertiary care center. All patients with a diagnosis of CF made at the Toronto CF Clinics between 1960 and June 2001. Data were collected prospectively and analyzed retrospectively. There were 73 of 1,051 patients (7%) with CF diagnosed in adulthood. Over time, an increasing number and proportion of patients received a diagnosis in adulthood: 27 patients (3%) before 1990, compared to 46 patients (18%) after 1990 (p < 0.001). The mean sweat chloride level was lower for those with CF diagnosed as adults, compared to those with a diagnosis as children (75 ± 26 mmol/L and 100 ± 19 mmol/L, respectively; p < 0.001) [mean ± SD], and adults were more likely to have pancreatic sufficiency (PS) than children (73% vs 13%, respectively; p < 0.0001). In 46 adults who received a diagnosis since 1990, the reason for the initial sweat test was pancreatitis (2 patients, 4%), pulmonary symptoms (18 patients, 39%), pulmonary and GI symptoms (10 patients, 22%), infertility (12 patients, 26%), and genetic screening (4 patients, 9%). Other manifestations were biliary cirrhosis (one patient) and diabetes mellitus (four patients, 9%). The diagnosis could be confirmed by sweat test alone in 30 of 46 patients (65%), by mutation analysis alone in 15 patients (33%), and by a combination in 31 patients (67%). Nasal potential difference (PD) measurements alone confirmed the diagnosis in the remaining 15 patients (33%). Patients with CF presenting in adulthood often have PS, inconclusive sweat test results, and a high prevalence of mutations that are not commonly seen in CF diagnosed in childhood. Although most patients have lung disease of variable degrees, single-organ manifestations such as congenital bilateral absence of the vas deferens and pancreatitis are seen. Repeated sweat tests and extensive mutation analysis are often required. Nasal PD may aid the diagnosis, but has not been standardized for clinical diagnosis.

Children with complex congenital heart disease are less active than recommended for optimal health, with social and physical environments important determinants. The purpose of this study was to examine the physical activity perceptions of children with complex congenital heart disease and their parents to identify social and physical environment intervention targets. A semi-structured discussion guide elicited physical activity perceptions from children (26 boys, 19 girls, 6.0–12.4 years) with complex congenital heart disease (single ventricle n = 42) and their parents during three child and three parent focus groups and 41 interviews. Interviews and focus groups were audio-recorded and transcribed verbatim for inductive thematic analysis. Children and parents identified home, peer and health environments as impacting on their children’s physical activity participation. Peer environments, such as school or daycare, were supportive by providing physical activity facilities and enabling fun with peers and time outdoors. At home, parent and sibling interactions both encouraged and discouraged physical activity. The children’s unique health environment fostered physical activity uncertainty, discouraging activity despite minimal or no physician recommendations to restrict physical activity. Children with complex congenital heart disease and their parents recognize the importance of physical activity and fun with friends. Physical activity uncertainty contributes to their inactive lifestyles despite minimal restrictions from health professionals. Positive clinical encouragement and health environment interventions that better support physical activity are required.

The Third National Health and Nutrition Examination Survey (NHANES III) reference is currently recommended for interpreting spirometry results, but it is limited by the lack of subjects younger than 8 years and does not continuously model spirometry across all ages. By collating pediatric data from other large-population surveys, we have investigated ways of developing reference ranges that more accurately describe the relationship between spirometric lung function and height and age within the pediatric age range, and allow a seamless transition to adulthood. Data were obtained from four surveys and included 3,598 subjects aged 4-80 years. The original analyses were sex specific and limited to non-Hispanic white subjects. An extension of the LMS (lambda, mu, sigma) method, widely used to construct growth reference charts, was applied. The extended models have four important advantages over the original NHANES III analysis as follows: (1) they extend the reference data down to 4 years of age, (2) they incorporate the relationship between height and age in a way that is biologically plausible, (3) they provide smoothly changing curves to describe the transition between childhood and adulthood, and (4) they highlight the fact that the range of normal values is highly dependent on age. The modeling technique provides an elegant solution to a complex and longstanding problem. Furthermore, it provides a biologically plausible and statistically robust means of developing continuous reference ranges from early childhood to old age. These dynamic models provide a platform from which future studies can be developed to continue to improve the accuracy of reference data for pulmonary function tests.

The advent of precision treatment for cystic fibrosis using small-molecule therapeutics has created a need to estimate potential clinical improvements attributable to increases in cystic fibrosis transmembrane conductance regulator (CFTR) function. To derive CFTR function of a variety of genotypes and correlate with key clinical features (sweat chloride concentration, pancreatic exocrine status, and lung function) to develop benchmarks for assessing response to CFTR modulators. CFTR function assigned to 226 unique genotypes was correlated with the clinical data of 54,671 individuals enrolled in the Clinical and Functional Translation of CFTR (CFTR2) project. Cross-sectional FEV % predicted measurements were plotted by age at which measurement was obtained. Shifts in sweat chloride concentration and lung function reported in CFTR modulator trials were compared with function-phenotype correlations to assess potential efficacy of therapies. CFTR genotype function exhibited a logarithmic relationship with each clinical feature. Modest increases in CFTR function related to differing genotypes were associated with clinically relevant improvements in cross-sectional FEV % predicted over a range of ages (6-82 yr). Therapeutic responses to modulators corresponded closely to predictions from the CFTR2-derived relationship between CFTR genotype function and phenotype. Increasing CFTR function in individuals with severe disease will have a proportionally greater effect on outcomes than similar increases in CFTR function in individuals with mild disease and should reverse a substantial fraction of the disease process. This study provides reference standards for clinical outcomes that may be achieved by increasing CFTR function.