Helicobacter pylori infection found during upper endoscopy performed for the diagnosis of celiac, inflammatory bowel diseases, and eosinophilic esophagitis: A multicenter pediatric European study.

BACKGROUND: Helicobacter pylori may be found during upper gastrointestinal endoscopy (UGE) performed to diagnose celiac disease (CeD), inflammatory bowel disease (IBD), and eosinophilic esophagitis (EoE). We aimed to describe the frequency of H. pylori in children undergoing UGE for CeD, IBD, and EoE and the number of children receiving eradication treatment. MATERIALS AND METHODS: A retrospective multicenter study from 14 countries included pediatric patients diagnosed with CeD, IBD, and EoE between January 2019 and December 2021. DATA COLLECTED: age, gender, hematologic parameters, endoscopic, histologic, and H. pylori culture results, and information on eradication treatment. RESULTS: H. pylori was identified in 349/3890 (9%) children [167 (48%) male, median 12 years (interquartile range 8.1-14.6)]. H. pylori was present in 10% (173/1733) CeD, 8.5% (110/1292) IBD and 7.6% (66/865) EoE patients (p = NS). The prevalence differed significantly between Europe (Eastern 5.2% (28/536), Southern 3.8% (78/2032), Western 5.6% (28/513)) and the Middle East 26.6% (215/809) [odds ratio (OR) 7.96 95% confidence interval (CI) (6.31-10.1) p < 0.0001]. Eradication treatment was prescribed in 131/349 (37.5%) patients, 34.6% CeD, 35.8% IBD, and 56.1% EoE. Predictors for recommending treatment included erosions/ulcers [OR 6.45 95% CI 3.62-11.47, p < 0.0001] and nodular gastritis [OR 2.25 95% CI 1.33-3.81, p 0.003]. Treatment rates were higher in centers with a low H. pylori prevalence (<20%) [OR 3.36 95% CI 1.47-7.66 p 0.004]. CONCLUSIONS: Identifying H. pylori incidentally during UGE performed for the most common gastrointestinal diseases varies significantly among regions but not among diseases. The indications for recommending treatment are not well defined, and less than 40% of children received treatment.

Hepatomegaly and fatty liver disease secondary to central hypothyroidism in combination with macrosomia as initial presentation of IGSF1 deficiency syndrome.

PURPOSE: IGSF1 deficiency syndrome (immunoglobulin superfamily member 1) is considered the most common sex-linked cause of secondary congenital hypothyroidism and is characterized by a wide variety of other clinical and biochemical features, including hypoprolactinemia, transient and partial growth hormone deficiency, early/normal timing of testicular enlargement but delayed testosterone rise in puberty, and adult macro-orchidism. Congenital central hypothyroidism is a rare disease (1:65,000 births); the detection of which may be delayed and missed by neonatal screening programs since most neonatal screening programs are based on TSH determination in dried blood spots only. Untreated hypothyroidism may cause abnormal liver biochemistry and non-alcoholic fatty liver disease. Our aim is to report a case of secondary hypothyroidism in an infant with an uncommon initial presentation. CASE PRESENTATION (METHODS/RESULTS): A 3-month-old male baby was referred to our hospital due to elevated alpha-fetoprotein levels, hypercholesterolemia, and macrosomia. Initial investigations revealed enlarged fatty liver and central hypothyroidism. Pituitary insufficiency was biochemically excluded and a pituitary MRI showed normal findings. Upon genetic analysis, a hemizygous variant NM_001170961.1:c.2422dup, p.(His808Profs*14), in IGSF1 gene was detected, establishing the diagnosis of the IGSF1 deficiency syndrome. In our patient, no other clinical findings were identified. Treatment with levothyroxine led to the remission of liver disease. CONCLUSION: Liver disease may be the initial presentation of secondary hypothyroidism in neonates and infants. Macrosomia in patients with isolated secondary central hypothyroidism is a strong indicator of IGSF1 syndrome.

Acute Hepatitis of Unknown Etiology Among Young Children: Research Agenda by the ESPGHAN Hepatology Committee.

In April 2022, an increased incidence of acute hepatitis cases of unknown etiology among previously healthy children across the United Kingdom was described. Since, more than 270 cases from the United Kingdom and hundreds more from all across the world have been reported. The majority of affected children were younger than 6 years of age. The clinical presentation was nonspecific with diarrhea and vomiting usually preceding the appearance of jaundice, abdominal pain, nausea, and malaise. Approximately 5% have required liver transplantation. An infectious etiology has been considered likely given the epidemiological and clinical features of the reported cases. Between 50 and 60% of the children tested were diagnosed with adenovirus infection although a clear etiological connection has still to be demonstrated. No link with SARS-CoV-2 infection and COVID-19 vaccine was found. What is not clear to date is whether the high number of acute hepatitis cases reported is related to a true increase in incidence or heightened awareness following on from the initial reports from the United Kingdom. The Hepatology Committee of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) developed a paper on the current outbreak of acute hepatitis of unknown etiology recognizing its importance and the need of approaching the current situation with a scientifically rigorous approach. The aims of the article are to summarize the current knowledge and to identify the most pertinent issues regarding the diagnosis and management of this condition and the research questions raised.

Proceedings of ESPGHAN Monothematic Conference 2020: "Acute Liver Failure in Children": Diagnosis and Initial Management.

OBJECTIVES: The Hepatology Committee of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) aims to educate pediatric gastroenterologists, members of ESPGHAN and professionals from other specialties promoting an exchange of clinical expertise in the field of pediatric hepatology. Herewith we have concentrated on detailing the recent advances in acute liver failure in infants and children. METHODS: The 2020 ESPGHAN monothematic three-day conference on pediatric hepatology disease, entitled "acute liver failure" (ALF), was organized in Athens, Greece. ALF is a devastating disease with high mortality and most cases remain undiagnosed. As knowledge in diagnosis and treatment of ALF in infants and children has increased in the past decades, the objective was to update physicians in the field with the latest research and developments in early recognition, curative therapies and intensive care management, imaging techniques and treatment paradigms in these age groups. RESULTS: In the first session, the definition, epidemiology, various causes of ALF, in neonates and older children and recurrent ALF (RALF) were discussed. The second session was dedicated to new aspects of ALF management including hepatic encephalopathy (HE), coagulopathy, intensive care interventions, acute on chronic liver failure, and the role of imaging in treatment and prognosis. Oral presentations by experts in various fields are summarized highlighting key learning points. CONCLUSIONS: The current report summarizes the major learning points from this meeting. It also identifies areas where there is gap of knowledge, thereby identifying the research agenda for the near future.

Proceedings of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition Monothematic Conference, 2020: "Acute Liver Failure in Children": Treatment and Directions for Future Research.

OBJECTIVES: The Hepatology Committee of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) aims to educate pediatric gastroenterologists, members of ESPGHAN and professionals from other specialties promoting an exchange of clinical expertise in the field of pediatric hepatology. METHODS: The 2020 single topic ESPGHAN monothematic 3-day conference on pediatric liver disease, was organized in Athens, Greece and was entitled " Acute Liver Failure" (ALF). ALF is a devastating disease with high mortality and in a considerable fraction of patients, the cause remains unresolved. As knowledge in diagnosis and treatment of ALF in infants and children has increased in the past decades, the objective was to update physicians in the field with developments in medical therapy and indications for liver transplantation (LT) and to identify areas for future research in clinical and neurocognitive outcomes in ALF. RESULTS: We recently reported the epidemiology, diagnosis, and initial intensive care management issues in separate manuscript. Herewith we report on the medical treatment, clinical lessons arising from pediatric studies, nutritional and renal replacement therapy (RRT), indications and contraindications for LT, neurocognitive outcomes, new techniques used as bridging to LT, and areas for future research. Oral presentations by experts in various fields are summarized highlighting key learning points. CONCLUSIONS: The current report summarizes the current insights in medical treatment of pediatric ALF and the directions for future research.

Dietary habits in Greek children with functional constipation based on Rome III criteria: a school-based, cross-sectional multivariate analysis.

BACKGROUND: Functional constipation (FC) is the most common gastrointestinal disorder of childhood and has a multifactorial etiology. We aimed to assess dietary habits in Greek children with FC compared to the general population (control group, CG). METHODS: This was a subgroup analysis of a school-based, cross-sectional study carried out in children 6-18 years of age, between January and June 2014, using the Rome III criteria for the diagnosis of FC. Dietary parameters, as well as socioeconomic and demographic data and their association with the likelihood of FC, were analyzed through multivariate logistic regression analysis and expressed as odds ratios (OR). RESULTS: A total of 1439 children (1218 CG, 221 FC) were included in the analysis. The final model showed that consumption of was the only dietary parameter significantly related to FC; higher frequency of consumption was inversely related to the likelihood of FC (OR: 0.98, 95% CI: 0.96, 0.99, P=0.048). Significant socioeconomic confounders with a positive association with FC were: parental educational level, victimization, physical activity and number of adults at home. CONCLUSIONS: Increased frequency of fiber consumption is significantly associated with higher odds of FC irrespective of socioeconomic background and lifestyle parameters. Interventional studies are required to validate these cross-sectional observations.

Diagnostic accuracy of two-dimensional shear wave elastography in detecting hepatic fibrosis in children with autoimmune hepatitis, biliary atresia and other chronic liver diseases.

BACKGROUND: Although fibrosis is the main determinant of liver stiffness, other disease-related factors usually disregarded in studies on liver elastography, such as inflammation and cholestasis, may influence liver stiffness. OBJECTIVE: To evaluate the accuracy of two-dimensional (2-D) shear wave elastography in assessing liver fibrosis in children with chronic liver disease by controlling for the confounding role of several disease- and patient-related factors. MATERIALS AND METHODS: Three disease groups were studied: 1) various chronic liver diseases, 2) autoimmune hepatitis and 3) biliary atresia. The METAVIR (meta-analysis of histological data in viral hepatitis) score was used for fibrosis staging and grading of necroinflammatory activity. Multiple linear regression was used to evaluate the relationship between liver stiffness measurements and disease-related factors. The diagnostic accuracy of elastography for predicting fibrosis stages was assessed by calculating the area under the receiver operating characteristic curves. RESULTS: The various chronic liver diseases group (n=32; 7.1±4.9 [mean±standard deviation] years) showed liver stiffness of 8.9±5.0 (mean±standard deviation) kPa, the autoimmune hepatitis group (n=33; 8.1±4.4 years) of 7.1±2.7 kPa, and the biliary atresia group (n=19; 0.2±0.1 years) of 19.7±15.2 kPa. Liver stiffness measurements differed across METAVIR fibrosis categories in all disease groups. The highest values were found in biliary atresia, at fibrosis stages ≥F2 (F2: 12.4±1.6 kPa, F3: 17.8±2 kPa, F4: 41.5±12.4 kPa). Liver stiffness was strongly associated only with fibrosis (P<0.0001) in various chronic liver diseases, but with necroinflammatory activity (P<0.0001) and fibrosis (P=0.002) in autoimmune hepatitis, and with age (P<0.0001), fibrosis (P<0.0001) and cholestasis (P=0.009) in biliary atresia. Optimal cutoffs for detecting advanced fibrosis (≥F3) were 16 kPa (area under curve: 0.98; sensitivity: 87.5%; specificity: 96.7%) in biliary atresia and 8.7 kPa (area under curve: 0.98; sensitivity: 93.8%; specificity: 96.1%) in other chronic liver diseases. CONCLUSION: Two-dimensional shear wave elastography is reliable in assessing liver fibrosis in children with chronic liver diseases.

Child and Parent Mental Health Problems in Pediatric Celiac Disease: A Prospective Study.

OBJECTIVES: The aim of our study was to estimate the levels of mental health problems in children with celiac disease (CD) along with their parents' mental health status, to compare these levels with those of healthy controls and to investigate how these problems are affected by a gluten-free diet (GFD). METHODS: Our study constituted 50 patients with CD at diagnosis before the initiation of a GFD (age 8.6 ±â€Š3.7 years, group A), 39 patients with CD on a GFD for at least 12 months (age 10.4 ±â€Š3.4 years, group B) and 38 healthy controls (age 7.7 ±â€Š3.8 years, group C), as well as their parents. One of the parents of each child completed the Child Behaviour Checklist (CBCL) and the Symptom Checklist 90 (SCL-90-R) to evaluate the children's and parents' mental health problems, respectively. Twenty patients in group A were reevaluated at least 12 months after initiation of a GFD (group D). RESULTS: At diagnosis, CD patients had higher scores in the CBCL for internalizing problems than healthy controls (55.7 ±â€Š10.3 vs 47.9 ±â€Š15.4, P = 0.007) and their parents demonstrated increased severity of mental health problems, including anxiety and depression, than the parents of healthy controls (0.72 ±â€Š0.49 vs 0.54 ±â€Š0.58, P = 0.013). CONCLUSIONS: CD patients at diagnosis and their parents, had more mental health problems, including anxiety and depression, than healthy controls.

Management of Hepatitis B Virus Infection and Prevention of Hepatitis B Virus Reactivation in Children With Acquired Immunodeficiencies or Undergoing Immune Suppressive, Cytotoxic, or Biological Modifier Therapies.

Reactivation of hepatitis B virus (HBV) is a known complication of immune-suppressive, cytotoxic, and biological modifier therapies in patients currently infected with HBV or who have had past exposure to HBV. Nowadays, newer and emerging forms of targeted biologic therapies are available for the management of rheumatologic conditions, malignancies, inflammatory bowel disease, dermatologic conditions and solid-organ, bone marrow, or haematologic stem cell transplant but there is currently a lack of a systematic approach to the care of patients with or at risk of HBV reactivation. The Hepatology Committee of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) together with a working group of ESPGHAN members with clinical and research expertise in viral hepatitis developed an evidence-based position paper on reactivation of HBV infection in children identifying pertinent issues addressing the diagnosis, prevention, and treatment of this condition. Relevant clinical questions were formulated and agreed upon by all the members of the working group. Questions were answered and positions were based on evidence resulting from a systematic literature search on PubMed and Embase from their inception to July 1, 2019. A document was produced and the working group and ESPGHAN Hepatology Committee members voted on each recommendation, using a formal voting technique. A recommendation was accepted provided upon agreement by at least 75% of the working group members. This position paper provides a comprehensive update on the diagnosis, prevention and treatment of HBV reactivation in children.

Performance of two--dimensional ultrasound shear wave elastography: reference values of normal liver stiffness in children.

BACKGROUND: Two-dimensional (2-D) shear wave elastography is a new sonographic elastography method for noninvasive measurement of liver stiffness. OBJECTIVE: The aim of this study was to establish reference values of normal liver stiffness on 2-D shear wave elastography in children. MATERIALS AND METHODS: Two-dimensional shear wave elastography values were measured in 202 children with no liver disease from the neonatal period to puberty, who were divided into 4 age groups: newborns and infants, preschoolers, elementary school children and adolescents. We investigated the effects of age, depth of elastography measurement, transducer, number of measurements per child, liver size and Doppler parameters of hepatic blood flow on liver elasticity values. RESULTS: The mean normal liver elasticity value in the study population was: 4.29±0.59  kilopascals (kPa). In neonates and infants, mean liver elasticity value was 4.63 (± 0.6) kPa, in preschoolers and elementary school children, 4.05 (± 0.57) kPa and 4.15 (± 0.52) kPa, respectively, and in adolescents, 4.39 (± 0.55) kPa. Values in neonates and infants as well as adolescents were significantly higher than in preschoolers and elementary school children (Kruskal-Wallis, P<0.001; Mann-Whitney U tests, P<0.05). There was no significant association between liver elasticity values and size of the right lobe or Doppler parameters of hepatic blood flow. Different depths and the number of elastography measurements had no effect on liver elasticity values. CONCLUSION: Two-dimensional shear wave elastography is achievable in a wide range of age in children. We established the reference values of normal liver stiffness on 2-D shear wave elastography in children.

Epigenetics in Paediatric Gastroenterology, Hepatology, and Nutrition: Present Trends and Future Perspectives.

Epigenetics can be defined as stable, potentially heritable changes in the cellular phenotype caused by mechanisms other than alterations to the underlying DNA sequence. As such, any observed phenotypic changes including organ development, aging, and the occurrence of disease could be driven by epigenetic mechanisms in the presence of stable cellular DNA sequences. Indeed, with the exception of rare mutations, the human genome-sequence has remained remarkably stable over the past centuries. In contrast, substantial changes to our environment as part of our modern life style have not only led to a significant reduction of certain infectious diseases but also seen the exponential increase in complex traits including obesity and multifactorial diseases such as autoimmune disorders. It is becoming increasingly clear that epigenetic mechanisms operate at the interface between the genetic code and our environment, and a large body of existing evidence supports the importance of environmental factors such as diet and nutrition, infections, and exposure to toxins on human health. This seems to be particularly the case during vulnerable periods of human development such as pregnancy and early life. Importantly, as the first point of contact for many of such environmental factors including nutrition, the digestive system is being increasingly linked to a number of "modern" pathologies. In this review article, we aim to give a brief introduction to the basic molecular principals of epigenetics and provide a concise summary of the existing evidence for the role of epigenetic mechanisms in gastrointestinal health and disease, hepatology, and nutrition.

Dental Caries and Periodontal Disease in Children and Adolescents with Inflammatory Bowel Disease: A Case-Control Study.

BACKGROUND: Previous reports have demonstrated a higher prevalence of dental caries and periodontal disease in adults with inflammatory bowel disease (IBD), but similar data in children and adolescents do not exist. The aim of the study was to evaluate the status of dental caries, oral hygiene, gingival status and periodontal treatment needs of children with IBD. METHODS: In this case-control study, 55 children on remission from a single outpatient IBD clinic, aged 4 to 18 years (12.27 ± 3.67 yr) and 55 matched systemically healthy controls of a dental practice were assessed prospectively. The evaluation included medical history, dental questionnaire in both groups, and previous and current medical therapy of children with IBD. Additionally, the decayed, missing, and filled tooth (dmf-t or DMF-T), simplified gingival, plaque control record and community periodontal treatment needs indices were evaluated. RESULTS: Children with IBD compared with controls had a statistically significant (P < 0.001) higher dmf-t (2.95 versus 0.91) or DMF-T (5.81 versus 2.04) index and a higher gingival inflammation (simplified gingival, 40% versus 24%) although the respectively dental plaque index showed no significant difference (plaque control record, 42% versus 41%). Also, the community periodontal treatment needs was significantly higher compared with controls (P < 0.001); most of the patients with IBD needed treatment of gingivitis (47% versus 4%), and none of them had healthy periodontium (0% versus 69%). CONCLUSIONS: The results of this case-control study demonstrate a higher frequency of dental caries, more clinical signs of gingival inflammation, and increased periodontal treatment needs in children and adolescents with IBD despite similar oral hygiene status.

Screening for coeliac disease in preschool Greek children: the feasibility study of a community-based project.

AIM: Evaluation of the prevalence of coeliac disease (CD) in Greek paediatric population. METHODS: The project consists of two parts: (i) a pilot study of preschool children aged 2-6 years to test the feasibility and diagnostic accuracy of community-based screening and (ii) a CD prevalence study, by random clustered sampling and proportionate stratification of various geographical areas in Greece. Trained nonmedical staff performed a rapid immunochromatographic test to detect IgA antibodies to tTG-IgA and IgA deficiency. Toddlers with positive results were referred to a paediatric gastroenterologist for further assessment with serum anti-tTG IgA and EMA-IgA. Children with positive serum anti-tTG and anti-EMA underwent upper gastrointestinal tract endoscopy and small bowel biopsy and were subsequently in gluten-free diet. RESULTS: In this project participated 1136 toddlers, who were tested at school. The prevalence of positive rapid anti-tTG screening was 1:154, of IgA deficiency 1:120 and of biopsy-proven CD 1:154. The prevalence of CD from this pilot study served as expected prevalence value for sample size calculation for the main prevalence study. CONCLUSION: This protocol using rapid immunochromatographic test for the detection of both IgA deficiency and CD is easy to be performed by nonmedical staff in a community setting, enabling the accurate identification of new CD cases among asymptomatic population.

Autoimmune hepatitis type-2 and Epstein-Barr virus infection in a toddler: art of facts or an artifact?

Epstein-Barr virus (EBV) can cause frequently asymptomatic (or anicteric) and self-limited hepatitis, while occasionally may result in considerable cholestatic hepatitis. Herein, we describe the case of a previously healthy toddler (26 month old girl) with prolonged cholestasis, elevated serum transaminases, EBV serology compatible with recent EBV infection and positive anti liver kidney microsomal antibody type 1 which is characteristic of new-onset autoimmune hepatitis type 2. Liver biopsy was also typical of autoimmune hepatitis as attested by the presence of portal inflammation with predominant T-lymphocytes and plasma cells and interface hepatitis. Persistent EBV-related hepatitis was excluded by the absence of viral inclusions and steatosis on liver specimens and negative liver EBV-PCR. In conclusion, our case strongly suggests that in children with prolonged cholestatic hepatitis, positive EBV serology cannot exclude the presence of other causes of liver disease. In this context, autoimmune hepatitis should be considered as an alternate diagnosis, particularly when there is specific liver-related autoantibody detection. In such conditions, liver biopsy seems mandatory in an attempt to achieve a correct and timely diagnosis of a potentially catastrophic disease as autoimmune hepatitis. Although some cases of autoimmune hepatitis type 1 following EBV infection have been reported in adults, to the best of our knowledge, the present case of autoimmune hepatitis type 2 after EBV infection represents the first case in children ever reported in the English literature.

Malrotation of the intestine and chronic volvulus as a cause of protein-losing enteropathy in infancy.

Protein-losing enteropathy in children is caused by intestinal metabolic, inflammatory, or infectious processes, or by lymphatic obstruction (intestinal lymphangiectasia). In this report, a 17-month-old child is presented with protein-losing enteropathy due to intestinal malrotation and chronic midgut volvulus causing lymphatic obstruction and spillage of lymph in the intestine and the peritoneum. This report should alert the pediatrician that intestinal malrotation should be added to the wide list of possible causes of protein-losing enteropathy in children.

New-onset autoimmune hepatitis in young patients with preexisting liver disease.

Autoimmune hepatitis (AIH) is thought to be a primary liver disease, occurring in the absence of any known etiology. We present three unusual cases of new-onset AIH in young female patients with longstanding preexisting liver disease (Alagille's syndrome, cystic fibrosis liver disease and sickle cell hepatopathy). All patients developed an insidious onset of abdominal pain, fatigue, jaundice and hepatitis after many years of their primary diagnosis and had negative serology for hepatitis A, B, C, cytomegalovirus and Epstein-Barr virus. The occurrence of AIH in these patients may be due to a complex interaction between the underlying liver disease, chronic medication use and genetic predisposition resulting in altered immunoregulatory mechanisms.

Hepatitis C treatment concomitant to chemotherapy as "salvage" therapy in children with hematologic malignancies.

In patients with malignancies, chronic hepatitis C reactivation or severe flare is uncommon and antiviral treatment is deferred mainly due to underlying bone marrow and immune suppression. We report the use of antiviral treatment concomitantly to chemotherapy in 3 children with hematologic malignancies, chronic hepatitis C, and significant liver dysfunction.

Inflammatory bowel disease in children: the role of a positive family history.

OBJECTIVES: The aim of this study was to evaluate any potential influence of a family history of inflammatory bowel disease (IBD) on the clinical phenotypes and the course of IBD in children. METHODS: In this retrospective study, the notes of 411 children with the diagnosis of IBD, 244 (59.4%) with ulcerative colitis, 129 (31.4%) with Crohn's disease and 38 (9.2%) with IBD unclassified, who were admitted to our department between 1 January 1981 and 31 December 2007 were reviewed. The aim was to assess the prevalence of familial IBD and its impact on the age of disease onset, clinical phenotypes according to the Montreal classification, course and outcome of disease. The control group consisted of IBD children without a family history of IBD, who were admitted to the hospital during the same time period. RESULTS: Thirty five (8.5%) children had a family history of IBD, (ulcerative colitis 6.6%, Crohn's disease 10.9% and IBD unclassified 13.2%). Sixty-eight percent of the 22 pairs of first-degree relatives were concordant for the clinical phenotype of disease. Significantly, more children with familial IBD had symptom onset and/or disease diagnosis before 5 years of age compared with sporadic IBD (P = 0.01 and P = 0.014, respectively); however, no differences were seen in sex, clinical phenotypes, need for aggressive treatment and/or surgery. CONCLUSION: Children with familial IBD had earlier onset of disease compared with those with sporadic IBD. However, this had no significant impact on the clinical phenotypes, the course and/or the outcome of disease.