Relationship between quality of life and behavioural disorders in children with persistent asthma: a Multiple Indicators Multiple Causes (MIMIC) model.

Knowledge on multiple interdependences between quality of life (QoL) and behavioural problems in relation to asthma severity and control is undetermined. The aims of the study were: (i) to assess the relationship of QoL and behavioural problems with asthma severity and control (ii) to predict children's "abnormal/borderline" status with variation in QoL. For these purposes a multicenter case-control study on 47 Severe Asthma (SA) and 94 Moderate Asthma (MA) children was performed. The MIMIC approach was applied to investigate the effect of SA and non-controlled asthma (NC) on QoL and behavioural disorders. Logistic regression was used to estimate probabilities of having an "abnormal/borderline" status with variation in QoL. The MIMIC model showed that the magnitude of the effect of SA and NC was larger on QoL (ß = -0.37 and ß = -0.30, respectively) than on behavioural problems (ß = 0.27). With regards to the probability of having a borderline status, in MA a QoL of 1 returned a probability of 0.81, whereas in SA a QoL of 1 returned a probability of 0.89. In conclusion, SA children are highly affected by impaired QoL and behavioural problems. The MIMIC model allowed us to obtain a comprehensive assessment of QoL and behavioural problems with asthma severity and control.

Effects of pidotimod and bifidobacteria mixture on clinical symptoms and urinary metabolomic profile of children with recurrent respiratory infections: a randomized placebo-controlled trial.

BACKGROUND: Many preschool children develop recurrent respiratory tract infections (RRI). Strategies to prevent RRI include the use of immunomodulators as pidotimod or probiotics, but there is limited evidence of their efficacy on clinical features or on urine metabolic profile. OBJECTIVE: To evaluate whether pidotimod and/or bifidobacteria can reduce RRI morbidity and influence the urine metabolic profile in preschool children. MATERIALS AND METHODS: Children aged 3-6 years with RRI were enrolled in a four-arm, exploratory, prospective, randomized, double-blinded, placebo-controlled trial. Patients were randomly assigned to receive pidotimod plus bifidobacteria, pidotimod plus placebo, bifidobacteria plus placebo or double placebo for the first 10 days of each month over 4 consecutive months. Respiratory symptoms and infections were recorded with a daily diary by parents during the study. Metabolomic analyses on urine samples collected before and after treatment were performed. RESULTS: Compared to placebo, children receiving pidotimod, alone or with bifidobacteria, had more symptom-free days (69 versus 44, p = 0.003; and 65 versus 44, p = 0.02, respectively) and a lower percentage of days with common cold (17% versus 37%, p = 0.005; and 15% versus 37%, p = 0.004, respectively). The metabolomic analysis showed that children treated with Pidotimod (alone or in combination with bifidobacteria) present, respect to children treated with placebo, a biochemical profile characterized by compounds related to the pathway of steroids hormones, hippuric acid and tryptophan. No significant difference in the metabolic profile was found between children receiving bifidobacteria alone and controls. CONCLUSIONS: Preschool children with RRI treated with pidotimod have better clinical outcomes and a different urine metabolomic profile than subjects receiving placebo. Further investigations are needed to clarify the connection between pidotimod and gut microbiome.

Congenital Lung Malformations: Unresolved Issues and Unanswered Questions.

Advances in prenatal and postnatal diagnosis, perioperative management, and postoperative care have dramatically increased the number of scientific reports on congenital thoracic malformations (CTM). Nearly all CTM are detected prior to birth, generally by antenatal ultrasound. After delivery, most infants do well and remain asymptomatic for a long time. However, complications may occur beyond infancy, including in adolescence and adulthood. Prenatal diagnosis is sometimes missed and detection may occur later, either by chance or because of unexplained recurrent or persistent respiratory symptoms or signs, with difficult implications for family counseling and substantial delay in surgical planning. Although landmark studies have been published, postnatal management of asymptomatic children is still controversial and needs a resolution. Our aim is to provide a focused overview on a number of unresolved issues arising from the lack of an evidence-based consensus on the management of patients with CTM. We summarized findings from current literature, with a particular emphasis on the vigorous controversies on the type and timing of diagnostic procedures, treatments and the still obscure relationship between CTM and malignancies, a matter of great concern for both families and physicians. We also present an algorithm for the assessment and follow-up of CTM detected either in the antenatal or postnatal period. A standardized approach across Europe, based on a multidisciplinary team, is urgently needed for achieving an evidence-based management protocol for CTM.

Advances in pediatrics in 2017: current practices and challenges in allergy, endocrinology, gastroenterology, genetics, immunology, infectious diseases, neonatology, nephrology, neurology, pulmonology from the perspective of Italian Journal of Pediatrics.

This review provides an overview of a remarkable number of significant studies in pediatrics that have been published over the past year in the Italian Journal of Pediatrics. We have selected information from papers presented in the Journal that deal with allergy, endocrinology, gastroenterology, genetics, immunology, infectious diseases, neonatology, nephrology, neurology, pulmonology. The relevant epidemiologic findings, and developments in prevention, diagnosis and treatment of the last year have been discussed and placed in context. We think that advances achieved in 2017 will help readers to make the future of patients better.

Pediatric severe asthma: a case series report and perspectives on anti-IgE treatment.

BACKGROUND: The primary goal of asthma management is to achieve disease control for reducing the risk of future exacerbations and progressive loss of lung function. Asthma not responding to treatment may result in significant morbidity. In many children with uncontrolled symptoms, the diagnosis of asthma may be wrong or adherence to treatment may be poor. It is then crucial to distinguish these cases from the truly "severe therapy-resistant" asthmatics by a proper filtering process. Herein we report on four cases diagnosed as difficult asthma, detail the workup that resulted in the ultimate diagnosis, and provide the process that led to the prescription of omalizumab. CASE PRESENTATION: All children had been initially referred because of asthma not responding to long-term treatment with high-dose inhaled steroids, long-acting ß2-agonists and leukotriene receptor antagonists. Definitive diagnosis was severe asthma. Three out four patients were treated with omalizumab, which improved asthma control and patients' quality of life. We reviewed the current literature on the diagnostic approach to the disease and on the comorbidities associated with difficult asthma and presented the perspectives on omalizumab treatment in children and adolescents. Based on the evidence from the literature review, we also proposed an algorithm for the diagnosis of pediatric difficult-to-treat and severe asthma. CONCLUSIONS: The management of asthma is becoming much more patient-specific, as more and more is learned about the biology behind the development and progression of asthma. The addition of omalizumab, the first targeted biological treatment approved for asthma, has led to renewed optimism in the management of children and adolescents with atopic severe asthma.

Advances in paediatrics in 2016: current practices and challenges in allergy, autoimmune diseases, cardiology, endocrinology, gastroenterology, infectious diseases, neonatology, nephrology, neurology, nutrition, pulmonology.

This review reports main progresses in various pediatric issues published in Italian Journal of Pediatrics and in international journals in 2016. New insights in clinical features or complications of several disorders may be useful for our better understanding. They comprise severe asthma, changing features of lupus erythematosus from birth to adolescence, celiac disease, functional gastrointestinal disorders, Moebius syndrome, recurrent pneumonia. Risk factors for congenital heart defects, Kawasaki disease have been widely investigated. New diagnostic tools are available for ascertaining brucellosis, celiac disease and viral infections. The usefulness of aCGH as first-tier test is confirmed in patients with neurodevelopmental disorders. Novel information have been provided on the safety of milk for infants. Recent advances in the treatment of common disorders, including neonatal respiratory distress syndrome, hypo-glycemia in newborns, atopic dermatitis, constipation, cyclic vomiting syndrome, nephrotic syndrome, diabetes mellitus, regurgitation, short stature, secretions in children with cerebral palsy have been reported. Antipyretics treatment has been updated by national guidelines and studies have excluded side effects (e.g. asthma risk during acetaminophen therapy). Vaccinations are a painful event and several options are reported to prevent this pain. Adverse effects due to metabolic abnormalities are reported for second generation antipsychotic drugs.

Clinical benefits, echocardiographic and MRI assessment after pulmonary sequestration treatment.

BACKGROUND: This study aimed to explore systematically procedural results, clinical benefits with echocardiographic and chest-MRI assessment of pulmonary sequestration percutaneous treatment. METHODS: 13 consecutive infants and children with diagnosis of isolated pulmonary sequestration (PS) had percutaneous closure of the aberrant artery supplying pulmonary sequestration between 2010 and 2015. By protocol, echocardiographic and chest-MRI assessment was performed before and respectively at 6-12months and 1year with the aim to study the effects of embolization on heart volume overload and regression of pulmonary sequestration. RESULTS: Median age at diagnosis was 1year (95%CI 0-2.6); median age at treatment was 1.3years (95%CI1.01-2.85). In all pts the PS was confirmed by chest-MRI. Procedural success was 100%. After treatment, pts experiencing previously respiratory symptoms/infections remained asymptomatic at 2.9year follow-up. In pts with significant shunt due to PS, treatment resulted in amelioration in left or right cardiac chamber enlargement at 6 and 12month follow-up. At distance from PS closure (median 14months), chest-MRI confirmed the closure of the aberrant artery and PS regression in 12 patients. In one case, despite the acute procedural success and the supplying artery remained closed, MRI detected residual PS revascularization. CONCLUSIONS: Percutaneous PS closure in infants and children is safe and provide regression in respiratory symptoms and heart chamber dilatation if significant shunt is present. MRI is able to define aberrant artery course and PS parenchima, and might represent a valid instrument to study residual PS parenchima during growth.

Lung structure and function similarities between primary ciliary dyskinesia and mild cystic fibrosis: a pilot study.

BACKGROUND: Primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) are increasingly compared. There are no chest magnetic resonance imaging (MRI) comparative studies of PCD and CF. We assessed clinical, functional, microbiological and MRI findings in PCD and mild CF patients in order to evaluate different expression of lung disease. METHODS: Twenty PCD (15.1 years) and 20 CF subjects with mild respiratory impairment (16 years, 70% with pancreatic insufficiency) underwent MRI, spirometry, and sputum cultures when clinically stable. MRI was scored using the modified Helbich system. RESULTS: PCD was diagnosed later than CF (9.9 versus 0.6 years, p = 0.03), despite earlier symptoms (0.1 versus 0.6 years, p = 0.02). In the year preceding the study, patients from both groups underwent two systemic antibiotic courses (p = 0.48). MRI total scores were 11.6 ± 0.7 and 9.1 ± 1 in PCD and CF, respectively. FEV1 and FVC Z-scores were -1.75 (range, -4.6-0.7) and -0.6 (-3.9-1.8) in PCD, and -0.9 (range, -5.4-2.3) and -0.3 (-3.4-2.5) in CF, respectively. No difference was found between lung function or structure, despite a higher MRI subscore of collapse/consolidation in PCD versus CF (1.6 ± 0.1 and 0.6 ± 0.2, p < 0.001). These findings were confirmed after data-control for diagnostic delay. Pseudomonas aeruginosa and Staphylococcus aureus were more frequent in CF than in PCD (p = 0.05 and p = 0.003, respectively). CONCLUSIONS: MRI is a valuable radiation-free tool for comparative PCD and CF lung disease assessment. Patients with PCD may exhibit similar MRI and lung function changes as CF subjects with mild pulmonary disease. Delay in PCD diagnosis is unlikely the only determinant of similarities.

Recurrent Pneumonia in Children: A Reasoned Diagnostic Approach and a Single Centre Experience.

Recurrent pneumonia (RP), i.e., at least two episodes of pneumonia in one year or three episodes ever with intercritical radiographic clearing of densities, occurs in 7.7%-9% of children with community-acquired pneumonia. In RP, the challenge is to discriminate between children with self-limiting or minor problems, that do not require a diagnostic work-up, and those with an underlying disease. The aim of the current review is to discuss a reasoned diagnostic approach to RP in childhood. Particular emphasis has been placed on which children should undergo a diagnostic work-up and which tests should be performed. A pediatric case series is also presented, in order to document a single centre experience of RP. A management algorithm for the approach to children with RP, based on the evidence from a literature review, is proposed. Like all algorithms, it is not meant to replace clinical judgment, but it should drive physicians to adopt a systematic approach to pediatric RP and provide a useful guide to the clinician.

Longitudinal Follow-up of Chronic Pulmonary Manifestations in Esophageal Atresia: A Clinical Algorithm and Review of the Literature.

In the past decades improved surgical techniques and better neonatal supportive care have resulted in reduced mortality of patients with esophageal atresia (EA), with or without tracheoesophageal fistula, and in increased prevalence of long-term complications, especially respiratory manifestations. This integrative review describes the techniques currently used in the pediatric clinical practice for assessing EA-related respiratory disease. We also present a novel algorithm for the evaluation and surveillance of lung disease in EA. A total of 2813 articles were identified, of which 1451 duplicates were removed, and 1330 were excluded based on review of titles and abstracts. A total of 32 articles were assessed for eligibility. Six reviews were excluded, and 26 original studies were assessed. Lower respiratory tract infection seems frequent, especially in the first years of life. Chronic asthma, productive cough, and recurrent bronchitis are the most common respiratory complaints. Restrictive lung disease is generally reported to prevail over the obstructive or mixed patterns, and, overall, bronchial hyperresponsiveness can affect up to 78% of patients. At lung imaging, few studies detected bronchiectasis and irregular cross-sectional shape of the trachea, whereas diffuse bronchial thickening, consolidations, and pleural abnormalities were the main chest X-ray findings. Airway endoscopy is seldom included in the available studies, with tracheomalacia and tracheobronchial inflammation being described in a variable proportion of cases. A complete diagnostic approach to long-term respiratory complications after EA is mandatory. In the presence of moderate-to-severe airway disease, patients should undergo regular tertiary care follow-up with functional assessment and advanced chest imaging.

Severe asthma features in children: a case-control online survey.

BACKGROUND: Very few studies have explored the distinguishing features of severe asthma in childhood in Europe, and only one study was conducted in Southern Europe. The aim of this study was to provide a detailed characterization of children with severe asthma treated in specialized pediatric asthma centers across Italy. METHODS: We conducted a web-based data collection of family, environmental, clinical and laboratory characteristics of 41 patients aged 6-17 years with severe asthma, defined according to the recent guidelines of the European Respiratory Society and the American Thoracic Society, and 78 age-matched peers with non-severe persistent asthma. The patients have been enrolled from 16 hospital-based pediatric pulmonology and allergy centers in Northern, Central, and Southern Italy. Logistic regression analysis assessed the relationship between patients' characteristics and severe asthma or non-severe persistent asthma. RESULTS: Features independently and significantly associated with severe asthma included lifetime sensitization to food allergens [Odds ratio (OR), 4.73; 95 % Confidence Interval (CI), 1.21-18.53; p = 0.03], lifetime hospitalization for asthma (OR, 3.71; 95 % CI, 1.11-12.33; p = 0.03), emergency-department visits for asthma during the past year (OR = 11.98; 95 % CI, 2.70-53.11; p = 0.001), and symptoms triggered by physical activity (OR = 12.78; 95 % CI, 2.66-61.40; p = 0.001). Quality-of-life score was worse in patients with severe asthma than in subjects with non-severe persistent asthma (5.9 versus 6.6, p = 0.005). Self-perception of wellbeing was compromised in more than 40 % of patients in both groups. Children with severe asthma had lower spirometric z scores than non-severe asthmatic peers (all p < 0.001), although 56 % of them had a normal forced expiratory volume in 1 s. No differences were found between the two groups for parental education, home environment, patients' comorbidities, adherence to therapy, exhaled nitric oxide values, and serum eosinophils and IgE . CONCLUSIONS: As expected, children with severe asthma had more severe clinical course and worse lung function than peers with non-severe persistent asthma. Unlike previous reports, we found greater sensitization to food allergens and similar environmental and personal characteristics in patients with severe asthma compared to those with non-severe persistent asthma. Psychological aspects are compromised in a large number of cases and deserve further investigation.

A disorder of surfactant metabolism without identified genetic mutations.

BACKGROUND: Surfactant metabolism disorders may result in diffuse lung disease in children. CASE PRESENTATION: We report a 3-years-old boy with dry cough, progressive hypoxemia, dyspnea and bilateral ground glass opacities at chest high-resolution computed tomography (HRCT) who had no variants in genes encoding surfactant proteins or transcription factors. Lung histology strongly suggested an abnormality of surfactant protein. A 7-month course of pulse intravenous high-dose methylprednisolone plus oral hydroxychloroquine and azithromycin led to gradual weaning from oxygen and oral steroids, and to improvement of cough and dyspnea. Over the follow-up period, hydroxychloroquine and azithromycin were not withdrawn as cough and dyspnea re-appeared at each attempt and disappeared at re-start. At 6 years of age chest HRCT still appeared unchanged, but clinical symptoms or signs were absent. CONCLUSIONS: In children suspected of inborn errors of pulmonary surfactant metabolism who do not have a recognized genetic mutation, lung biopsy with consistent histology may help physicians to address the definitive diagnosis.

Hypovitaminosis D: a novel finding in primary ciliary dyskinesia.

BACKGROUND: A relationship between low levels of serum vitamin D and respiratory infections has been established. No study has examined the frequency and clinical relevance of vitamin D deficiency in patients with primary ciliary dyskinesia (PCD). METHODS: Vitamin D levels were measured in 22 PCD patients (7 females, 10.5 years, range, 2-34 years). In PCD, pulmonary function tests (PFTs), sputum microbiology, self-reported physical activity (PA) level, and quality of life (QoL) by means of the Saint George's Respiratory Questionnaire (SGRQ), were also assessed. RESULTS: Seventy-two percent of PCD patients were vitamin-D deficient-to-insufficient and 28% were sufficient. No differences in PFTs parameters were found between vitamin D deficiency-to-insufficiency and sufficiency groups. Patients with vitamin D deficiency-to-insufficiency had significantly higher SGRQ total scores, and thus poorer QoL (p = 0.03). Seventy-nine percent of PCD subjects had limitations in performing vigorous activities, and 53% performed less than 3 hours of PA per week. Vitamin D deficiency-to-insufficiency and sufficiency groups did not show any differences in age at PCD diagnosis or at onset of respiratory symptoms, BMI, atopy, current asthma or bronchiectasis. However, 79% of patients with bronchiectasis had vitamin D deficiency-to-insufficiency. No differences were found in the rate of positive sputum cultures and in the number of antibiotic courses between the two groups. CONCLUSIONS: Hypovitaminosis D is common in PCD patients, and is associated with poorer QoL. We recommend the assessment and treatment of hypovitaminosis D to be included in the routine management of PCD.

Clinical application of nasal nitric oxide measurement in pediatric airway diseases.

Nitric oxide plays an important role in several physiological and pathophysiological processes in the respiratory tract. Different ways to measure nasal nitric oxide levels in children are currently available. The possibility of obtaining nasal nitric oxide measurement from relatively young children, combined with the availability of portable devices that can be used even in the office setting, opens new perspectives for nasal nitric oxide analysis in the pediatric daily practice. This review presents a synopsis about the current clinical applications of nasal nitric oxide measurement in the pediatric clinical practice. A total of 3,775 articles on the topic were identified, of which 883 duplicates were removed, and 2,803 were excluded based on review of titles and abstracts. Eighty-nine full text articles were assessed for eligibility and 32 additional articles were obtained from the reference lists of the retrieved studies. Since very low nasal nitric oxide levels are found in the majority of patients with primary ciliary dyskinesia, most publications support a central role for nasal nitric oxide to screen the disease, and indicate that it is a very helpful first-line tool in the real-life work-up in all age groups. Decreased nasal nitric oxide concentration is also typical of cystic fibrosis, even though nasal nitric oxide is not as low as in primary ciliary dyskinesia. In other upper airway disorders such as allergic rhinitis, rhinosinusitis, nasal polyposis, and adenoidal hypertrophy, clinical utility of nasal nitric oxide is still critically questioned and remains to be established. Since nNO determination is flow dependent, a general consensus from the major investigators in this area is highly desirable so that future studies will be performed with the same flow rate. A shared nNO methodology will enable to overcome the challenges that lie ahead in incorporating nNO measurement into the mainstream clinical setting of pediatric airway diseases.

Sleep disordered breathing and airway disease in primary ciliary dyskinesia.

BACKGROUND AND OBJECTIVE: Sleep-disordered breathing (SDB) may develop in primary ciliary dyskinesia (PCD), leading to these diseases worsening one another. METHODS: Sixteen stable PCD patients (4.9-17.2 years) and 42 controls underwent overnight respiratory polysomnography (rPSG) and Sleep Disturbances Scale for Children (SDSC). In PCD we assessed nasal endoscopy, pulmonary function tests and chest high-resolution computed tomography (HRCT). RESULTS: Compared with controls, PCD had higher obstructive apnoea (4.7 vs 0.2, P < 0.001), central apnoea (0.8 vs 0.2, P < 0.001), hypopnoea (1.8 vs 0.2, P < 0.001), apnoea-hypopnoea (7.8 vs 0.6, P < 0.001), oxygen desaturation indexes (ODI; 0.7 vs 0.2, P = 0.002), and mean oxygen desaturation (4% vs 1%, P < 0.001), while mean and nadir oxygen saturation (97.1% vs 98.1, P < 0.001) (93% vs 97.2%, P < 0.001) were lower, respectively. In PCD, SDSC was unrelated to rPSG (P > 0.05), with total score and subscores of disorders in initiating and maintaining sleep, and sleep-wake transition lower than controls. PCD patients had chronic rhinosinusitis (100%) and adenoidal hypertrophy (50%). Total HRCT score was 7 (range 0-14). ODI correlated with functional residual capacity (r = 0.8, P = 0.02), total HRCT (r = 0.6, P = 0.03) and peribronchial thickening scores (r = 0.7, P = 0.02). Oxygen saturation was associated with bronchiectasis severity score (r = -0.6, P = 0.02). CONCLUSIONS: PCD's parents may underestimate SDB. As nocturnal desaturation is associated with lung function and structure abnormalities, SDB may significantly contribute to pulmonary morbidity.

Multicenter analysis of body mass index, lung function, and sputum microbiology in primary ciliary dyskinesia.

BACKGROUND: No studies longitudinally, simultaneously assessed body mass index (BMI) and spirometry in primary ciliary dyskinesia (PCD). METHODS: We determined BMI and spirometry in 158 PCD children and adolescents from London, UK (n = 75), Naples, Italy (n = 23) and Copenhagen, Denmark (n = 60) at first presentation and during follow-up. Annual BMI and spirometry were prospectively collected and analyzed over blocks of 2, 4, and 6 consecutive years. Sputum pathogens were recorded. RESULTS: Age at first spirometry was 8.7 years (range, 4.2-17.4). Mean Z scores of first measured BMI, FEV1, FVC, and FEF(25-75) were 0.01, -1.37, -0.84, and -1.68, respectively. First spirometry was not more frequently impaired in patients referred at age ≥6 years than in those referred at preschool age (P = 0.13). There were no differences in slopes for BMI, FEV1, FVC, or FEF(25-75) over any time block. H. influenzae was the most common pathogen, isolated at least once in 65% of patients. P. aeruginosa was found in 58 subjects (37%) of whom 8 (5%) were chronically infected. Neither pathogens was associated with spirometry changes. CONCLUSIONS: Preschool referral to a PCD center was not associated with better spirometry or BMI. PCD children and adolescents receiving centralized care show steady BMI and spirometry during medium term follow-up. There was a high prevalence of Pseudomonas aeruginosa infection, but the evolution of spirometry or BMI was not affected by this microorganism in medium term. Despite our longitudinal analysis showed no differences between the three centers, the assessment of spirometry and BMI over time represents a quality improvement tool. Future studies are needed to highlight the role of spirometry and BMI in long term PCD management and identify subgroups of patients with a higher risk of early lung failure or nutritional problems.

Respiratory manifestations in patients with inherited metabolic diseases.

Growing evidence indicates that inherited metabolic diseases are increasingly being recognised. Life expectancy for many patients is progressively improving because new therapeutic strategies are available. Because most inherited metabolic diseases are systemic disorders, virtually all organs may be involved. Respiratory disease complicates the management of several inherited metabolic diseases, either at presentation or as late-onset features. This review will describe the most exemplary respiratory manifestations of inherited metabolic diseases in childhood and adulthood. Since airways disease worsens the morbidity of many inherited metabolic disorders, leading to increased hospitalisations, mortality and overall healthcare costs, respiratory manifestations of inherited metabolic diseases need to be carefully recognised and treated. All patients with inherited metabolic disease and suspected airway disease should undergo a detailed diagnostic work-up. Current treatments for several inherited metabolic diseases (including enzyme replacement therapy, substrate reduction, bone marrow transplantation, or even more innovative strategies such as pharmacological chaperone or gene therapies) may provide significant benefits for associated respiratory disease. The integration of several specialists dedicated to airway disease management in a multidisciplinary team is essential to provide the most appropriate care to children and adults with inherited metabolic disease.