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- Study Description
This longitudinal observational study will investigate the natural history and progression of four genetic causes of intrahepatic cholestasis of childhood, including alpha-1 antitrypsin deficiency (α1-AT), Alagille syndrome (AGS), progressive familial intrahepatic cholestasis (PFIC), and bile acid synthesis defects (BAD). This study will be conducted as part of the Cholestatic Liver Disease Consortium (CLiC), an NIH-funded multi-centered Rare Disease Clinical Research Consortium. In this study, we will collect defined data elements in a uniform fashion at fixed intervals for five years over a relatively large number of patients with these rare disorders. In addition, a biobank of patient specimens and DNA samples will be established for use in ancillary studies to be performed in addition to this study. By comparing outcome measures between the four liver diseases (i.e., using each disorder as a disease-control for the other disorders), the full impact of each disorder can best be determined in comparison to the other liver diseases. Using the longitudinal database in this fashion, this study will provide an improved understanding of the effects of the cholestatic liver during childhood irrespective of the underlying etiology as well as to the pathophysiology, outcome, and complications of each of the disorders. This initial characterization will allow calculation of sample sizes for future therapeutic intervention clinical trials and provide the baseline to which interventions should be compared.
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- Authorized Access
- Publicly Available Data (Public ftp)
Connect to the public download site. The site contains release notes and manifests. The site also contains data dictionaries, variable summaries, documents, and truncated analyses, whenever available.
- Study Inclusion/Exclusion Criteria
All current and newly diagnosed patients with alpha-1-antitrypsin deficiency, Alagille syndrome, PFIC, and bile acid synthesis and metabolism defects, both before and after liver transplant, followed at or referred to each CLiC Clinical Site will be offered enrollment into this study. Sibling of participants with alpha-1-antitrypsin deficiency and Alagille syndrome, who themselves have the underlying disease but without liver involvement, will also be offered enrollment. After informed consent is obtained, participants will be enrolled into this study through five Groups (described in Study Group section below). The inclusion criteria are:
- Children and young adults diagnosed with one of the four cholestatic diseases from birth through 25 years old.
- Siblings of participants with alpha-1-antitrypsin deficiency or Alagille syndrome, who themselves have alpha-1-antitrypsin deficiency or Alagille syndrome but no evidence of liver disease.
- Both genders, all races and ethnic groups
- Participant meets the enrollment criteria for one of the four cholestatic liver diseases.
Exclusion criteria include:
- Inability to comply with the longitudinal follow-up, or
- Failure of a family/patient to sign the informed consent document or the HIPAA medical record release form.
Participants with each of the four cholestatic liver diseases will be enrolled at each CLiC center, including those who are currently followed at the centers, new patients to the CLiC centers, and siblings of specific diseases. At the additional Enrollment Center, only participants with alpha-1 anti-trypsin deficiency will be enrolled. Participants will be enrolled via five Groups in order to facilitate the appropriate collection of data. The five Groups are the following:
- Group 1: Infants < 6 months of age at diagnosis and enrolled in the BARC PROBE study
- Group 2: Participants age 6 months through 25 years old at enrollment and not previously enrolled in BARC PROBE study
- Group 3: Post-liver transplant participants
- Group 4: Screening enrollment
- Group 5: Affected siblings (without evidence of liver disease) of Alpha-1 Antitrypsin Deficiency and Alagille Syndrome participants who are enrolled in CLiC.
Group One applies to infants who were initially enrolled at < 6 months of age into the Biliary Atresia Clinical Research Consortium (BARC) Prospective Biliary Atresia Epidemiology study (PROBE study; P003). BARC is an NIH-funded cooperative research network, funded by NIDDK, which is based in 10 Clinical Sites of CLiC. BARC has a different Data Coordinating Center (DCC), which enters BARC data into a SQUL database, collecting most of the data elements required for the enrollment data collected in CLiC. For these BARC participants, once the definitive diagnosis of a CLiC disease is established, these participants will be offered enrollment into this CLiC study, re-consented for this longitudinal study and enrolled in this CLiC study, as well as continued in the BARC study. Participants may be any age, up to and including 25 years old. Follow-up for both studies will be done concurrently in a seamless fashion, so that the required data elements will be acquired for both studies by the same study coordinator at the same time. At the time of CLiC enrollment, initial BARC data will be downloaded from the BARC DCC to the CLiC DTCC, and subsequent data collected for CLiC will be shared with BARC, and downloaded from the CLiC DTCC to the BARC DCC. Any additional CLiC data that is not collected on the BARC CRFs will be collected on a CLiC CRF. Consent forms and HIPAA forms for both studies will include a statement describing data sharing with the other study.
Group Two will apply to currently established patients at one of the CLiC Clinical Sites who have one of the CLiC diseases and are ≥ 6 months through 25 years of age, or patients with one of these diseases who are newly referred to CLiC Clinical Sites at these ages, and who are not enrolled in BARC PROBE study.
Group Three will be for participants with CLiC diseases, birth through 25 years old, who have undergone liver transplantation and are either followed at or referred to the CLiC clinical sites. These patients will have a limited data-set collected and limited CLiC follow-up, but will be essential for the studies of genotype-phenotype relationships, of modifier genes and of natural history of each disease. They will be enrolled for an abbreviated data collection visit and to collect blood for preparation of cell lines or DNA for genetic studies.
Group Four is a screening group of participants, birth through 25 years old, suspected of having AGS, PFIC or BAD, who do not meet complete enrollment criteria for Groups 1 or 2. In this Group, CLiC Core laboratories will perform bile acid analysis to detect BAD or genotyping for AGS or PFIC on participants that the investigator believes may have one of these diseases, and who would need these tests in order to establish the diagnosis and make the participant eligible for enrollment in Groups 1 or 2. Consent will be obtained, a set of brief enrollment CRFs will be filled out, and specimens will be collected from the participant and parents for genotyping (PFIC or AGS), or from the participant for urine bile acid analysis. No specimens will be sent to the Repositories for this Group.
Group Five is for enrollment of siblings of participants with A1AT deficiency or AGS, birth through 25 years old, who themselves are found to be PIZZ and PISZ upon clinical testing or meet AGS criteria and who do not have evidence of liver disease. Criteria for evidence of liver disease are hepatomegaly or splenomegaly, abnormal hepatic function tests, complications of chronic liver disease, abnormal imaging of the liver (except for fatty liver), or abnormal liver biopsy histology. Enrollment of these participants will be important in order to determine if the liver disease in A1AT deficiency breeds true in families, supporting a modifier genetic or environmental factor, as well as for genotype/phenotype relationships in AGS. Affected siblings with evidence of liver disease can be enrolled in Groups 1, 2, or 3.
- Study History
Clinical Significance of Genetic Causes of Intrahepatic Cholestasis
Genetic causes of intrahepatic cholestasis compose a unique subset of rare diseases that need a more concentrated national effort to better understand the molecular and cellular basis of these disorders, the natural history and the medical, developmental and social consequences on the child and family, and to develop new therapeutic approaches. The four rare liver disorders that will be the focus of this study are all considerations in evaluating infants with a cholestatic disorder (jaundice, conjugated hyperbilirubinemia and elevated serum bile acid concentrations), a condition that occurs in one of 2,500 live births. These four disorders, which as a group account for approximately 20-30% of all infants presenting with neonatal cholestasis, cause significant morbidity and growth problems during childhood, lead to progressive cholestasis (impaired bile flow), hepatic fibrosis and ultimately cirrhosis of the liver with its incumbent complications (including death), and are among the leading indications for liver transplantation in childhood. Each of these disorders involves perturbations in different intracellular pathways of protein and lipid metabolism, targeting different key organelles, yet producing similar, but individualized clinical features. For example, α1-AT deficiency involves retention of an abnormally folded protein in the endoplasmic reticulum (ER) of liver cells. This pathologic state is associated with mitochondrial dysfunction and quality control mechanisms, including proteasomal degradation, autophagic degradation and activation of other “stress” signaling pathways, appear to be critically important in determining whether tissue injury occurs. PFIC involves retention of bile acids that most likely stimulate plasma membrane death receptors and causes direct mitochondrial toxicity inducing cellular apoptotic machinery. Bile acid synthesis disorders involve failure to produce protective bile acids and overproduction of toxic bile acids which may stimulate these same pathways leading to rapid onset of hepatocellular failure. Alagille syndrome involves anatomically impaired failure of bile acid and other solute secretion by the hepatocyte producing similar intracellular consequences.
Because of the common pathophysiologic feature of intrahepatic cholestasis, the injured liver in all of these conditions fails to adequately secrete bile into the intestinal tract, which is essential for normal digestion and excretion of cholesterol and drug metabolites. The consequent very significant malabsorption of dietary fat and fat-soluble vitamins poses a major obstacle to normal nutrition in these growing children. The resulting negative energy and nitrogen balance lead to poor linear growth and decreased lean body mass and subcutaneous adipose tissue stores, having a profound effect on the child's ability to function normally and maintain adequate immune function to protect against common childhood illnesses. Micronutrient deficiencies (e.g., vitamin E, zinc, vitamin A) may produce irreversible neurological, developmental and retinal deficits if not recognized and promptly treated. In addition, cholestasis-induced pruritus (itching) may be devastating in affected children, interfering with sleep, daily activities and school performance and causing intractable scratching and skin infections. Cholestasis also directly causes hypercholesterolemia and disfiguring skin xanthoma formation. The jaundice frequently persists, further impacting on the child's physical appearance and self-esteem. Over time, as hepatic fibrosis progresses to cirrhosis, the liver fails to synthesize and release important proteins, lipids and carbohydrates for the rest of the child's body, remove and metabolize toxins, xenobiotics and metabolic by-products, and store essential nutrients. These abnormalities may affect cognitive development, brain growth, and linear growth, producing long-term irreversible extrahepatic morbidity.
When irreversible signs of end-stage liver disease or intractable cholestasis develop, children with these cholestatic disorders are frequently evaluated for liver transplantation as their only option for survival, a costly procedure that demands life-long immunosuppression to prevent allograft rejection in almost all cases. In the Studies for Pediatric Liver Transplantation (SPLIT) database, 56 children with Alagille syndrome, 54 with alpha-1 antitrypsin deficiency, and 25 with PFIC were among the 1761 children who were listed for liver transplantation between 1995 and 2002 at 38 North American liver transplant centers (SPLIT 2002 Annual Report). An additional 42 children with “other” cholestatic and 21 with “other” metabolic disorders may have had these diseases but were undiagnosed. Thus, these four disorders account for almost 10% of all children who are evaluated and listed for liver transplantation in the United States. Unfortunately, current non-surgical treatment for these four diseases is generally inadequate because of a poor understanding of the molecular, biochemical and cellular basis of liver injury.
Finally, diagnostic procedures for some of these disorders require complex genetic evaluation, surgical liver biopsies, or difficult biochemical testing. The development of more available simple diagnostic testing for these disorders would enhance the ability of caregivers to establish the diagnoses quickly and institute therapies.
In summary, the four rare liver disorders of focus in this study are a serious group of related diseases that demand more rigorous investigation in order to develop a scientific basis for improvements in diagnosis and treatment. The first step in advancing our understanding of these cholestatic disorders and improving our diagnostic capabilities is to develop a prospective longitudinal database study which includes a sufficient number of patients for adequate characterization of clinical phenotype; defining the clinical, biochemical, neurodevelopmental, quality of life and survival outcome; developing and validating biomarkers of disease progression, and the collection of banked genomic DNA and liver biopsy RNA for genetic studies. Furthermore, a longitudinal cohort study of patients with these liver diseases will help accelerate clinical research and progress in understanding the pathogenesis of rare causes of intrahepatic cholestasis by more carefully defining the natural history of each disease and by providing an infrastructure in which to investigate better means of diagnosis and of treatment. The rarity of these diseases and the difficulty in timely diagnosis makes it difficult to accumulate an adequate number of patients followed for an adequate period of time at a single clinical center. Furthermore, a uniform coordinated approach to evaluation and follow-up will reduce the number of patients needed to ensure adequate statistical power.
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