Clinical, neuroimaging, and molecular spectrum of TECPR2-associated hereditary sensory and autonomic neuropathy with intellectual disability.

Bi-allelic TECPR2 variants have been associated with a complex syndrome with features of both a neurodevelopmental and neurodegenerative disorder. Here, we provide a comprehensive clinical description and variant interpretation framework for this genetic locus. Through international collaboration, we identified 17 individuals from 15 families with bi-allelic TECPR2-variants. We systemically reviewed clinical and molecular data from this cohort and 11 cases previously reported. Phenotypes were standardized using Human Phenotype Ontology terms. A cross-sectional analysis revealed global developmental delay/intellectual disability, muscular hypotonia, ataxia, hyporeflexia, respiratory infections, and central/nocturnal hypopnea as core manifestations. A review of brain magnetic resonance imaging scans demonstrated a thin corpus callosum in 52%. We evaluated 17 distinct variants. Missense variants in TECPR2 are predominantly located in the N- and C-terminal regions containing ß-propeller repeats. Despite constituting nearly half of disease-associated TECPR2 variants, classifying missense variants as (likely) pathogenic according to ACMG criteria remains challenging. We estimate a pathogenic variant carrier frequency of 1/1221 in the general and 1/155 in the Jewish Ashkenazi populations. Based on clinical, neuroimaging, and genetic data, we provide recommendations for variant reporting, clinical assessment, and surveillance/treatment of individuals with TECPR2-associated disorder. This sets the stage for future prospective natural history studies.

Hospital versus home treatment of respiratory exacerbations in cystic fibrosis.

BACKGROUND: Treatment of respiratory exacerbations in Cystic Fibrosis (CF) is important in slowing disease progression. The treatment may be given either at home or at the hospital. The aim of our study was to compare both treatment settings. MATERIAL/METHODS: We retrospectively analyzed data of 139 treatments in 54 CF patients (age range 12-47 y) treated for respiratory exacerbations at the hospital (n = 84) and/or at home (n = 55). Primary outcomes were improvement in pulmonary function tests (PFTs), weight gain and duration of treatment in relation to treatment setting. Secondary outcomes were these same parameters, but in relation to different clinical preconditions and CF-related complications. RESULTS: Mean improvement in FEV1 (% predicted) was similar between the hospital and home treatments (14.3 ± 34.4% vs. 14.3 ± 20.2%, respectively; NS), yet treatment duration was significantly shorter at the hospital (9.7 ± 6.7 vs. 16.3 ± 9.1 days, respectively; P < 0.02), especially for patients colonized with Pseudomonas aeruginosa (11.1 ± 5.5 vs. 18.0 ± 11.0 days, respectively; p<0.01). At the hospital, a subgroup of patients with CF-related complications improved their FEV1 significantly more than those at home (13.1 ± 19.4% vs. 1.9 ± 14.9%, respectively; P < 0.02), particularly patients with CF-related diabetes mellitus (CFRDM) (11.4 ± 18.7% vs. 1.7 ± 14.6%, respectively; P < 0.05). Patients tended to gain more weight at the hospital compared to home treatment (1.36 ± 4.6 kg and 0.49 ± 3.6 kg respectively; P = 0.06). CONCLUSIONS: Hospital treatment for acute respiratory exacerbations in CF may be superior to home treatment, as indicated by a shorter duration of hospitalization, better improvement in FEV1 in patients with CF-related complications, CFRDM in particular and a trend toward better weight gain.

Meconium ileus in patients with cystic fibrosis is not a risk factor for clinical deterioration and survival: the Israeli Multicenter Study.

OBJECTIVES: Patients with cystic fibrosis (CF) presenting with meconium ileus (MI) tend to have worse outcomes than those without MI. We evaluated the clinical characteristics and survival rates among Israeli patients with CF with and without MI after a prolonged follow-up (15-30 years). PATIENTS AND METHODS: A multicenter retrospective study. Forty-nine patients with CF, representing 13.8% of all patients with CF in Israel, presented with MI (current age 17.4 +/- 7.9 years) between 1975 and 2006. They were compared with 38 patients with CF (current age 19.3 +/- 6.5 years) without MI matched by sex and CF transmembrane conductance regulator mutation. RESULTS: A total of 66.2% of patients with MI and 73.6% without MI were followed for a prolonged period (24.9 +/- 2.7 years). Of the patients with MI, 31 were managed operatively, whereas 18 were treated successfully with gastrograffin enema, with similar clinical outcomes. Five patients in the MI group and 3 in the control group died during the study period. Bacterial colonization, z score of body mass index, and pulmonary function tests were similar in patients with and without MI in the long term. In younger patients, many clinical parameters were more prevalent in patients with MI (P = 0.004). However, these differences disappeared after the long-term follow-up (up to 31-years). CONCLUSIONS: Patients with CF presenting with MI had similar pulmonary function and nutritional status, as well as survival rates as did the control patients without MI. The distinct genetic mutation found in our population may explain in part the favorable results compared with other studies. In addition, it seems that early diagnosis and treatment of MI in patients with CF may be beneficial, subsequently lowering morbidity, and increasing survival.

Flexible bronchoscopy and bronchoalveolar lavage in pediatric patients with lung disease.

OBJECTIVE: The use of flexible bronchoscopy (FOB) and bronchoalveolar lavage (BAL) in investigating pediatric patient with airway abnormalities and pulmonary infiltrates are indispensable and are now a routine procedure in many centers. Immunocompromised and cancer patients, especially after bone marrow transplantation, and children who have undergone surgery for congenital heart disease (CHD) are at high risk for pulmonary disease. Our aim was to study the diagnostic rate, safety, and clinical yield of FOB in critically ill pediatric patients. DESIGN: : Retrospective chart review. SETTING: Pediatric intensive care unit in a tertiary university hospital. PATIENTS: Three hundred nineteen children who underwent 335 FOB procedures. The indications for bronchoscopy included infectious agent identification in immune-competent patients with new pulmonary infiltrates seen on chest radiograph (46%) and in patients with fever and neutropenia with respiratory symptoms (18%), airway anatomy evaluation in patients with upper airway obstruction (16%), CHD (15%), and airway trauma (5%). Data were obtained by reviewing the patients' charts, bronchoscopy reports, and laboratory results. MEASUREMENTS AND MAIN RESULTS: The diagnostic rate of FOB procedures was 79%. FOB and BAL resulted in alteration of management (positive clinical yield) in 70 patients (23.9%). A definite infectious organism was identified in 56 patients (17.6%). The clinical yield in patients with cancer or primary immune deficiency (38.7%) was significantly higher compared with patients with CHD (20.4%, p < 0.01) and pneumonia (17%, p < 0.01). Major complications were observed in two procedures (prolonged apnea), and minor complications (transient desaturation, stridor, and minor bleeding) were observed in 45 patients (14%). CONCLUSIONS: FOB and BAL have an important role in the evaluation of airway abnormality and pulmonary infiltrate in pediatric patients, in whom rapid and accurate diagnosis is crucial for survival. We suggest that FOB should be considered as an initial diagnostic tool in those critically ill patients.

Exercise challenge test in 3- to 6-year-old asthmatic children.

RATIONALE: The exercise challenge test (ECT) is a common tool to assess exercise-induced asthma (EIA) in school-aged children. EIA has not been explored in the early childhood setting. OBJECTIVE: To assess the existence of EIA in children in this age group. MEASUREMENTS AND MAIN RESULTS: A 6-min, controlled, free-run test was performed in 55 children (age range, 3 to 6 years old) who were classified into the following groups: 30 children in whom asthma had been previously diagnosed (group A); and 25 children with prolonged coughing (group B). Spirometry measurements were obtained before the run, and at 1, 2, 3, 5, 10, and 20 min after the run. A positive finding of EIA was defined as a 13% decrease from baseline FEV(1) or baseline forced expiratory volume in the first 0.5 s (FEV(0.5)). The actual duration of each run was age-related (mean [+/- SD] duration, 4.8 +/- 0.8 min). The nadir in indexes occurred after a mean time of 2.98 +/- 1.31 min. A positive EIA finding determined by FEV(1) was present in 15 children, and by FEV(0.5) in 34 children. Twenty-six children were from group A, but only 8 children were from group B. Wheezing and/or prolonged expiration were associated with a positive test result in 31 of 34 children. Coughing was frequent in children with both negative and positive ECT findings. CONCLUSION: The present study documents for the first time the presence of EIA in response to a free-run test in early childhood. Our findings suggest that a free-run test for the presence of EIA is suitable, but that the running duration is limited by age. The duration of airflow limitation after exercise is significantly earlier and shorter in young children with asthma compared with older children. FEV(0.5) is a better index than the traditional FEV(1) for describing positive ECT results in young children. The association of wheezing and/or prolonged expiration may help in defining EIA in early childhood in the absence of a spirometer.

Spirometry in early childhood in cystic fibrosis patients.

BACKGROUND: Spirometry data in cystic fibrosis (CF) patients in early childhood is scarce, and the ability of spirometry to detect airways obstruction is debatable. OBJECTIVE: To evaluate the ability of spirometry to detect airflow obstruction in CF patients in early childhood. METHODS: CF children (age range, 2.5 to 6.9 years) in stable clinical condition were recruited from five CF centers. The children performed guided spirometry (SpiroGame; patented by Dr. Vilzone, 2003). Spirometry indices were compared to values of a healthy early childhood population, and were analyzed with relation to age, gender, and clinical parameters (genotype, pancreatic status, and presence of Pseudomonas in sputum or oropharyngeal cultures). RESULTS: Seventy-six of 93 children tested performed acceptable spirometry. FVC, FEV1, forced expiratory flow in 0.5 s (FEV0.5), and forced expiratory flow at 50% of vital capacity (FEF50) were significantly lower than healthy (z scores, mean +/- SD: - 0.36 +/- 0.58, - 0.36 +/- 0.72, - 1.20 +/- 0.87; and - 1.80 +/- 1.47, respectively; p < 0.01); z scores for FEV1 and FVC were similar over the age ranges studied. However, z scores for FEV0.5 and forced expiratory flow at 25 to 75% of vital capacity were significantly lower in older children compared to younger children (p < 0.001), and a higher proportion of 6-year-old than 3-year-old children had z scores that were > 2 SDs below the mean (65% vs 5%, p < 0.03). Girls demonstrated lower FEF50 than boys (z scores: - 2.42 +/- 1.91 vs - 1.56 +/- 1.23; p < 0.001). Clinical parameters evaluated were not found to influence spirometric indices. CONCLUSIONS: Spirometry elicited by CF patients in early childhood can serve as an important noninvasive tool for monitoring pulmonary status. FEV0.5 and flow-related volumes might be more sensitive than the traditional FEV1 in detecting and portraying changes in lung function during early childhood.

Melatonin treatment in adolescents with delayed sleep phase syndrome.

This retrospective study describes the effects of long-term treatment with melatonin in 33 adolescents (age range, 10-18 years) with delayed sleep phase syndrome (DSPS). Patients were treated with oral melatonin, 3 to 5 mg/day for an average period of 6 months. During the treatment, sleep onset was advanced and sleep duration was longer. Treatment was also associated with a decrease in the proportion of patients reporting school difficulties. No adverse effects of melatonin were noted. This study indicates that long-term treatment with melatonin can be beneficial for adolescents with DSPS in terms of sleep-wake schedule and school performance.

TECPR2 mutations cause a new subtype of familial dysautonomia like hereditary sensory autonomic neuropathy with intellectual disability.

BACKGROUND: TECPR2 was first described as a disease causing gene when the c.3416delT frameshift mutation was found in five Jewish Bukharian patients with similar features. It was suggested to constitute a new subtype of complex hereditary spastic paraparesis (SPG49). RESULTS: We report here 3 additional patients from unrelated non-Bukharian families, harboring two novel mutations (c.1319delT, c.C566T) in this gene. Accumulating clinical data clarifies that in addition to intellectual disability and evolving spasticity the main disabling feature of this unique disorder is autonomic-sensory neuropathy accompanied by chronic respiratory disease and paroxysmal autonomic events. CONCLUSION: We suggest that the disease should therefore be classified as a new subtype of hereditary sensory-autonomic neuropathy. The discovery of additional mutations in non-Bukharian patients implies that this disease might be more common than previously appreciated and should therefore be considered in undiagnosed cases of intellectual disability with autonomic features and respiratory symptoms regardless of demographic origin.

Pregnancies and outcome in women with cystic fibrosis.

BACKGROUND: Along with the increased life expectancy in cystic fibrosis and the remarkable progress in its management and therapy, issues of female fertility and pregnancy are frequently raised. These include infertility, severity of lung disease, pancreatic insufficiency, poor nutritional status, glucose intolerance and diabetes, drug safety, and long-term maternal and neonatal outcome. OBJECTIVE: To describe the experience of our CF center in the management of CF pregnant woman from 1977 to 2004. METHODS: We analyzed 27 years of records (1977-2004) of the national CF registry of all CF women who wished to conceive and became pregnant. RESULTS: Eight CF women (mean age 24 +/- 4.5 years) who wished to conceive had 11 pregnancies and delivered 12 neonates. The pregestational results of forced expiratory volume per 1 second varied significantly among patients (59 +/- 23%), yet most (10/11) stayed stable throughout the pregnancy course. Maternal deterioration in CF condition occurred in only one mother, necessitating cesarean section. In 9 of the 11 pregnancies the women were pancreatic-insufficient. Of the 11 pregnancies, 2 CF women had diabetes mellitus and 3 developed gestational diabetes. One pregnancy occurred in a mother with a transplanted lung. Of the 12 neonates, 3 were preterm and one was born with esophageal atresia. No miscarriages, terminations or neonatal mortalities occurred. Although most of the CF mothers had FEV1 below 55% before pregnancy, the maternal and neonatal outcome was favorable and lung function tests generally remained stable. CONCLUSIONS: We conclude that pregnancy in CF is feasible with a positive maternal and neonatal outcome. Early participation of the CF physician in the wish of the CF woman to reproduce is required. The integration of an intensive multidisciplinary approach during pregnancy, which includes close follow-up of maternal and fetal condition by the various specialists, should ensure an optimal outcome.

Effects of an intensive 4-week summer camp on cystic fibrosis: pulmonary function, exercise tolerance, and nutrition.

STUDY OBJECTIVES: Cystic fibrosis (CF) patients prefer exercise to most other forms of therapy, although objective improvement remains controversial. Israeli CF patients have attended a summer program in Switzerland for many years with subjective improvement. However, CF camps worldwide have been cancelled recently, due to fears of cross-infection with resistant organisms. Therefore, we evaluated the effect of attending the camp on pulmonary function, exercise tolerance, and nutritional state in CF patients. DESIGN: Weight, resting pulmonary function, incremental exercise test results, and sputum culture findings were assessed before and after a 4-week intensive summer camp. SETTING: Davos, Switzerland (altitude, 1,500 m). PATIENTS: Thirteen Israeli CF patients (seven women and six men) with an age range of 9 to 25 years who had mild-to-moderate lung disease. No patients had Burkholderia cepacia detected in their sputum. INTERVENTIONS: The program included a high-calorie diet, chest physiotherapy, daily mountain climbing, and indoor activities. Arterial oxygen saturation (SaO(2)) was maintained at > 88% during exertion. RESULTS: Exercise tolerance improved significantly. The peak work capacity increased by 12.7%, the maximal oxygen uptake increased by 10%, and minute ventilation increased by 18.5% (p < 0.0005). Of the calculated parameters, the anaerobic threshold improved by 17%. Ventilation was always the limiting factor during exercise, although it improved. There was no significant change in resting lung function and pulse or in SaO(2) decline at maximal exercise. The mean weight gain was 1 kg. No patient acquired B cepacia. CONCLUSIONS: An intensive summer camp improved exercise tolerance and nutrition in CF patients. This may explain improved patient well-being despite unchanged values for resting lung function. The reinstitution of summer camps, with special care to avoid cross-infection, should be considered.

Reversal of digital clubbing after lung transplantation in cystic fibrosis patients: a clue to the pathogenesis of clubbing.

Digital clubbing is a common sign in cystic fibrosis (CF) and in a variety of other diseases. However, its pathogenesis remains obscure. In diseases other than CF, regression of clubbing has been noted after cure of the underlying disease. The aim of this study was to assess whether clubbing is reversible in CF patients after lung transplantation. Digital clubbing was investigated in 3 CF patients, prior to and after lung transplantation. Distal phalangeal depth (DPD) and interphalangeal depth (IPD) of the index finger were measured using a skinfold caliper, and the DPD/IDP ratio was calculated. The mean DPD/IDP ratio was 1.08 +/- 0.05 prior to transplantation and 1.00 +/- 0.06, 0.96 +/- 0.06, 0.92 +/- 0.04, and 0.89 +/- 0.07 at 3, 6, 12, and 24 months after transplantation, respectively. In all 3 patients, the DPD/IDP ratio was greater than 1 before transplantation. In 2 patients, this ratio decreased to less than 1 within 3 months, and in the third patient within 9 months after surgery. We conclude that digital clubbing is reversible in CF patients who undergo lung transplantation. Regression was usually noted during the first 3 months posttransplantation. This could be explained either by adequate inactivation of a circulating clubbing-inducing molecule by the normal transplanted lungs, or by removal of the diseased lungs in which this presumably causative substance was produced.

Liver cirrhosis and portal hypertension in cystic fibrosis.

OBJECTIVES: Liver disease is the second cause of death in cystic fibrosis. The most deleterious complication of liver disease is portal hypertension, which has an estimated prevalence of up to 8%. Portal hypertension may manifest itself by splenomegaly, hypersplenism, gastro-oesophageal bleeding and ascites. The aim of our study was to determine the prevalence, risk factors and invasive management of portal hypertension at our centre. METHODS: One hundred and fifty patients with cystic fibrosis were followed up between 1975 and 2000 in the national cystic fibrosis centre in Israel. Forty patients (27%) had liver disease. All underwent clinical evaluation and laboratory and imaging studies. RESULTS: Portal hypertension was diagnosed in 10 patients (7%), of whom eight were male. The mean age at diagnosis was 11 years (range, 4-17 years). All had severe mutations of the cystic fibrosis transmembrane conductance regulator gene (the CFTR gene), pancreatic insufficiency, meconium ileus or distal intestinal obstruction syndrome and variceal bleeding. Seven patients underwent sclerotherapy to control acute bleeding. Four underwent portosystemic shunting (functioning up to 37 years). Two patients with severe lung and liver disease underwent transjugular intrahepatic portosystemic shunting, which provided bleeding control, but both died while waiting for lung/liver transplantation. One patient underwent liver transplantation due to liver failure and still had good liver and lung function 10 years later. CONCLUSIONS: Portal hypertension is more common among Israeli patients with cystic fibrosis. The unique genetic composition of our population may explain this phenomenon. Risk factors include male gender, pancreatic insufficiency, severe CFTR mutations, meconium ileus and meconium ileus equivalent. Sclerotherapy is the main option to control oesophageal variceal bleeding, while portosystemic shunts offer a prolonged alternative treatment for refractory bleeding. A transjugular intrahepatic portosystemic shunt and liver transplantation may also be effective, but further research is required in order to establish their role.

Long-term non-invasive positive pressure ventilation among cystic fibrosis patients awaiting lung transplantation.

BACKGROUND: Pulmonary disease is the most frequent cause of morbidity and mortality in cystc fibrosis patients. New techniques such as non-invasive positive pressure ventilation have resulted in prolongation of life expectancy in CF patients with end-stage lung disease. OBJECTIVES: To determine the role of NIPPV in CF patients awaiting lung transplantation. METHODS: Between 1996 and 2001 nine CF patients (5 females) with end-stage lung disease were treated with bi-level positive airway pressure ventilation in the "spontaneous" mode. RESULTS: The patients' mean age at initiation of BiPAP was 15 years (range 13-40 years) and the mean duration of BiPAP usage was 8 months (range 3-16 months). Four patients underwent successful lung transplantation, three patients died while awaiting transplantation, and the remaining two are still on NIPPV while waiting for transplantation. Patients' body mass index increased significantly (P < 0.05) during BiPAP therapy (from 16.1 to 17.2 kg/m2). Blood pH, PaCO2, and bicarbonate improved significantly (from 7.31 to 7.38, 90.8 to 67.2 mmHg, and 48.9 to 40.3 mEq/L, respectively). Pulmonary function tests were not affected by BiPAP usage. The patients experienced a significant alleviation in morning headaches and improvement in quality of sleep (P < 0.003). There were no major complications during BiPAP usage. CONCLUSIONS: We demonstrated that long-term NIPPV can stabilize and improve physiologic parameters such as ventilation, arterial blood gases and body mass index, as well as subjective symptoms such as sleep pattern, daily activity level, and morning headaches in CF patients with end-stage lung disease. Further prospectively controlled studies are needed to evaluate the potential of BiPAP therapy and its influence on morbidity and mortality in the post-lung transplantation period.

Aeration properties of a new sleeping surface for infants.

BACKGROUND: Prone sleeping position, use of soft mattresses and head covering by bedclothes are known risk factors for sudden infant death syndrome (SIDS). Rebreathing carbon dioxide (CO(2) ) may be a possible mechanism or a confounding factor of SIDS. OBJECTIVE: To compare the aeration properties of a new concept of infant sleeping surface (Net) to three commercial mattresses advertised to improve aeration and to two standard infant mattresses. DESIGN: Two experiments were performed: (I) A container (head box), filled with 7% CO(2) mixture, was opened to the mattress to allow gas mixture to passively diffuse outside and equilibrate with the surrounding room air. (II) Simulation of normal breathing of an infant, using a unidirectional reciprocal syringe, to determine CO(2) accumulation within the head box. METHODS: CO(2) concentrations in the head box were continuously measured until CO(2) levels fell below 1% or for 5 min (experiment I), or until CO(2) accumulation levels plateaued or for 6 min (experiment II). RESULTS: The Net had a significantly faster rate of CO(2) elimination (88.5 ± 4.6 and 91.9 ± 0.9 sec, Net alone and when covered with a sheet, respectively) compared to 238.3 ± 14.2 sec to 387.8 ± 7.9 sec for the other mattresses (P < 0.001). Only the Net was able to prevent CO(2) accumulation with maximal CO(2) levels (0.56 ± 0.03% and 1.16 ± 0.05%; Net alone and when covered with a sheet, respectively) significantly lower than the range of 4.6-6.3% for the other mattresses (P < 0.001). CONCLUSIONS: The new sleeping surface exhibited significantly better aeration properties in dispersing CO(2) and in preventing its accumulation.

Outcome of patients with cystic fibrosis admitted to the intensive care unit: is invasive mechanical ventilation a risk factor for death in patients waiting lung transplantation?

OBJECTIVE: The admission of patients with cystic fibrosis (CF) to the intensive care unit (ICU) is controversial. Our aim was to study the long-term outcome of patients with CF who were admitted to the ICU and the effect of ventilation modality. METHODS: The medical records of 104 admissions (1996-2006) of 48 patients with CF (age 18+/-9 years) were reviewed. Seventeen patients were admitted with reversible conditions (group 1). Thirty-one patients were admitted for acute on chronic respiratory failure (group 2). RESULTS: In group 1, 16 of 17 patients survived up to 10 years from ICU admission. Conversely, in group 2, 23 of 31 patients (74%) died of respiratory failure. In group 2, 17 of 18 patients who were mechanically ventilated died within 90 days from admission, and 7 of 10 patients treated for prolonged periods with bi-level positive airway pressure are still alive up to 10 years after admission and transplantation. CONCLUSION: Patients requiring mechanical ventilation may have a poor prognosis. The outcome of treatment with bi-level positive airway pressure is good, even in patients who had many episodes of acute respiratory failure.

The relation between age and time to maximal bronchoconstriction following exercise in children.

BACKGROUND: The exercise challenge test (ECT) is a common tool for assessment of asthma in children. Many studies suggest that the "time to maximal bronchoconstriction" (Nadir-t) after exercise challenge in asthmatic children may be age-dependent, although this has never been systematically studied. Such findings may influence epidemiological surveys where the schedule of post-exercise measurements is trimmed. This study systematically assesses the relation between age and time to maximal bronchoconstriction post-ECT. METHODS: Data were collected retrospectively from 131 subjects (87 male; 3-18 years) who were referred for ECT. The routine ECT was performed according to ATS recommendation of a 6-min run. Spirometry was measured at 1, 3, 5, 10, 15, and 20 min post-exercise. The post-exercise nadir of FEV1 (%baseline) (FEV1-nadir) and the time to maximal fall in Nadir-t (minutes) were sought and values were related to age. RESULTS: Baseline FEV1 values (mean+/-SD) were 90.5+/-13.8% predicted. FEV1-nadir was -23.6+/-11.7% from baseline values. The Nadir-t was reached at 5.1+/-2.6 min (range 2-12 min). A positive correlation between children's age and Nadir-t was observed (r2=0.542; SD of residuals=1.79; p<0.001), regardless of FEV1-nadir, whether the cutoff of point was -10% or -15% of baseline FEV1. Children <10 years of age showed Nadir-t at 3.4+/-1.7 min post-exercise and older children at 6.6+/-2.5 min post-exercise (p<0.0001). CONCLUSION: Our results indicate that the time to maximal bronchoconstriction is age-dependent in children and adolescents, and imply that the schedule of post-exercise FEV(1) measurements should be cautiously trimmed.