Alpha-1-Antitrypsin Deficiency: Outcomes After Liver Transplantation

Respiratory problems associated with liver disease in children

Respiratory manifestations of chronic liver disease have a profound impact on patient clinical outcomes. Certain conditions within paediatric liver disease have an associated respiratory pathology. This overlap between liver and respiratory manifestations can result in complex challenges when managing patients and requires clinicians to be able to recognise when referral to specialists is required. While liver transplantation is at the centre of treatment, it opens up further potential for respiratory complications. It is established that these complications place patients at risk of longer stays in hospital and reduced survival. Additionally, late post-transplant complications can occur, including post-transplant lymphoproliferative disease and immunosuppression-induced interstitial lung disease. Although rare, it is important for clinicians to recognise these conditions to allow for prompt management. Finally, as liver disease progresses in children, respiratory complications can occur. Hepatopulmonary syndrome can occur in the context of portal hypertension, resulting in increased mortality and poorer quality of life for patients. Another consequence is portopulmonary hypertension, which can be associated with poor survival. Failure to recognise these complications in children may result in poorer outcomes and therefore it is vital that clinicians can establish when referral to a paediatric respiratory medicine specialist is required.

Pediatric and Adult Liver Disease in Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency (AATD) arises due to inherited variants in SERPINA1, the AAT gene that impairs the production or secretion of this hepatocellular protein and leads to a gain-of-function liver proteotoxicity. Homozygous Pi*Z pathogenic variant (Pi*ZZ genotype) is the leading cause of severe AATD. It manifests in 2 to 10% of carriers as neonatal cholestasis and 20 to 35% of adults as significant liver fibrosis. Both children and adults may develop an end-stage liver disease requiring liver transplantation. Heterozygous Pi*Z pathogenic variant (Pi*MZ genotype) constitutes an established disease modifier. Our review summarizes the natural history and management of subjects with both pediatric and adult AATD-associated liver disease. Current findings from a phase 2 clinical trial indicate that RNA silencing may constitute a viable therapeutic approach for adult AATD. In conclusion, AATD is an increasingly appreciated pediatric and adult liver disorder that is becoming an attractive target for modern pharmacologic strategies.

Assessing Patients with Alpha-1 Antitrypsin Deficiency for Corneal Refractive Surgery: A Review and Clinical Experience

Alpha-1 Antitrypsin Deficiency (AATD) is an autosomal inheritable disorder that impairs the protease inhibitor alpha-1 antitrypsin. This disorder presents with various systemic effects, including liver cirrhosis, centrilobular emphysema, and ocular manifestations. Performing corneal refractive surgery in patients with AATD raises concerns regarding the increased rates of corneal erosions, corneal ulcerations, potential developing descemetoceles, and other ocular manifestations. Patient outcomes for laser-assisted in situ keratomileuses (LASIK), photorefractive keratectomy (PRK), small incision lenticule extraction (SMILE), and other ocular corrective surgeries are lacking in this population. This article provides experiences performing corneal refractive surgery, discusses the current understanding of AATD, including its ocular manifestations, and explores factors to consider when evaluating patients for corneal procedures. The aim of this paper is to address the manifestations of AATD prior to performing corrective vision surgery.

Update Alpha-1-Antitrypsin-Mangel

Der Alpha-1-Antitrypsin-Mangel (AATM) ist mit einer Prävalenz bis zu 1:2000 eine der häufigsten monogenetischen Ursachen für eine Lebertransplantation im Kindesalter. Pulmonal manifestiert sich der AATM erst im Erwachsenenalter. Er wird oft zu spät oder überhaupt nicht diagnostiziert. Die initiale Diagnostik ist mit einer Serumspiegelbestimmung einfach und günstig durchführbar. Bei Werten unter 1,1 g/l sollte eine Genotypisierung erfolgen, die im Alpha-1-Antitrypsin-Zentrum Marburg kostenfrei angeboten wird. Aufgrund des sehr heterogenen Verlaufs sollte die weiterführende Betreuung von Patienten mit AATM jedoch Spezialisten mit ausreichender Erfahrung vorbehalten bleiben. Hierfür eignen sich insbesondere die pädiatrischen Alpha-1-Center. Einen hohen Stellenwert haben die Aufklärung sowie die Aufrechterhaltung einer guten Compliance mit regelmäßigen ärztlichen Verlaufskontrollen, um eine Progredienz der Lebererkrankung zu erfassen. Neben Anamnese und körperlicher Untersuchung sind regelmäßige Blutentnahmen und Ultraschalluntersuchungen (inkl. Leberelastographie) notwendig. Therapeutisch stehen neben einer kurativen Lebertransplantation derzeit lediglich supportive Therapien zur Wahl. Sollte eine Lebertransplantation indiziert sein, ist das Langzeit-Outcome erfreulicherweise sehr gut.

Pulmonary Abnormalities in Liver Disease: Relevance to Transplantation and Outcome

Pulmonary disease in liver cirrhosis and portal hypertension (PH) constitutes a challenging clinical scenario and may have important implications with regard to prognosis, liver transplantation (LT) candidacy, and post-LT outcome. Pre-LT evaluation should include adequate screening for pulmonary diseases that may occur concomitantly with liver disease as well as for those that may arise as a complication of end-stage liver disease and PH, given that either may jeopardize safe LT and successful outcome. It is key to discriminate those patients who would benefit from LT, especially pulmonary disorders that have been reported to resolve post-LT and are considered "pulmonary indications" for transplant, from those who are at increased mortality risk and in whom LT is contraindicated. In conclusion, in this article, we review the impact of several pulmonary disorders, including cystic fibrosis, alpha 1-antitrypsin deficiency, hereditary hemorrhagic telangiectasia, sarcoidosis, coronavirus disease 2019, asthma, chronic obstructive pulmonary disease, pulmonary nodules, interstitial lung disease, hepatic hydrothorax, hepatopulmonary syndrome, and portopulmonary hypertension, on post-LT survival, as well as the reciprocal impact of LT on the evolution of lung function.

Lung and liver transplantation in patients with alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin (AAT) augmentation is effective in slowing the progression of emphysema due to AAT deficiency (AATD) but cannot prevent eventual progression to end-stage lung disease and complete respiratory failure, which is the leading cause of death for individuals with severe AATD. When patients develop end-stage lung disease, lung transplantation is the only treatment option available, and this can improve lung physiology and patient health status. The available data suggest that survival rates for lung transplantation are significantly higher for patients with AATD-related chronic obstructive pulmonary disease (COPD) compared with non-AATD-related COPD, but, conversely, there is a higher risk of common post-lung transplant complications in patients with AATD versus non-AATD COPD. Nevertheless, lung transplantation (single and bilateral) is favorable for patients with AATD. After respiratory failure, the second leading cause of death in patients with AATD is liver disease, for example, cirrhosis and hepatocellular carcinoma, caused by the accumulation of mutant forms of AAT retained within the liver. As with lung disease, the only treatment option for end-stage liver disease is liver transplantation. Survival rates for patients with AATD undergoing liver transplantation are also favorable, and patients, particularly pediatric patients, have benefitted from advancements in peri-/post-surgical care. As the majority of AAT is produced by the liver, the AAT phenotype of the recipient becomes that of the donor, meaning that AAT serum levels should be normalized (if the donor is AAT-replete), halting further lung and liver disease progression. However, post-liver transplant respiratory function may continue to decline in line with normal age-related lung function decline. In the most severe cases, where patients have simultaneous end-stage lung and liver disease, combined lung and liver transplantation is a treatment option with favorable outcomes. However, there is very little information available on this procedure in patients with AATD.

A review of liver dysfunction in the lung transplant patient

Liver dysfunction is an increasingly common finding in patients evaluated for lung transplantation. New or worsening dysfunction in the perioperative period, defined by presence of clinical ascites/encephalopathy, high model for end-stage liver disease (MELD) score, and/or independent diagnostic criteria, is associated with high short- and long-term mortality. Therefore, a thorough liver function assessment is necessary prior to listing for lung transplant. Unfortunately, identification and intraoperative monitoring remain the only options for prevention of disease progression with isolated lung transplantation. Combined lung and liver transplantation may provide an option for definitive long-term management in selecting patients with known liver disease at high risk for postoperative progression. However, experience with the combined operation is extremely limited and indications for combined lung and liver transplant remain unclear. Herein, we present a comprehensive literature review of patients with liver dysfunction undergoing lung transplantation with and without concurrent liver transplant in an effort to illuminate the risks, benefits, and clinical judgement surrounding decision to pursue combined lung-liver transplantation (CLLT). We also argue description of liver function is currently a weakness of the current lung allocation scoring system. Additional algorithms incorporating liver function may aid in risk stratification and decision to pursue combined transplantation.

Long term results of liver transplantation for alpha-1 antitrypsin deficiency

INTRODUCTION

Liver transplantation (LT) is the therapeutic option for end-stage liver disease associated with alpha1 antitrypsin (A1AT) deficiency. The aim of the present retrospective study was to report on long-term outcomes following LT for A1AT deficiency.

METHODS

The medical records of 90 pediatric and adult patients transplanted between 1982 and 2017 in France and Geneva (Switzerland) were reviewed.

RESULTS

The study population consisted of 32 adults and 58 children; median age at transplant was 13.0 years (range: 0.2-65.1), and 65 were male (72.2%). Eighty-two patients (94.8% of children and 84.4% of adults) had the PI*ZZ genotype/phenotype and eight patients (8.9%) had the Pi*SZ genotype/phenotype. Eighty-four patients (93.3%) were transplanted for end-stage liver disease and six (all Pi*ZZ adults) for HCC. Median follow-up after LT was 13.6 years (0.1-31.7). The overall cumulative patient survival rates post-transplant were 97.8% at 1 year, and 95.5%, 95.5%, 92.0%, 89.1% at 5, 10, 15, 20 years respectively. The overall cumulative graft survival rates were 92.2% at 1 year, and 89.9%, 89.9%, 84.4%, 81.5% at 5, 10, 15 and 20 years, respectively.

CONCLUSIONS

In a representative cohort of patients having presented with end-stage-liver disease or HCC secondary to A1AT, liver transplantation offered very good patient and graft survival rates.

Alpha-1 antitrypsin deficiency liver disease

The clinical presentation of liver disease is highly variable in homozygous ZZ alpha-1 antitrypsin (AAT) deficiency, and not all patients with the homozygous ZZ genotype develop liver disease. Although not fully identified, there is likely a strong influence of genetic and environmental modifiers of the intracellular injury cascade and fibrotic response. Most ZZ children are well and remain undiagnosed. Of those who come to medical attention, the most common pediatric presentation is neonatal cholestatic hepatitis, sometimes referred to as "neonatal hepatitis syndrome". The gold standard for diagnosis of AAT deficiency is analysis of the AAT protein phenotype in the patient serum or the genotype of their DNA genome. Careful follow up of all diagnosed children is important. Heterozygotes for S and Z alleles of AAT (SZ) may develop progressive liver disease similar to ZZ patients and also require close monitoring. There is no specific treatment for AAT deficiency induced liver disease and current therapy remains supportive with management of complications. Rarely, patients require liver transplant and typically the patient outcomes are excellent. With improved understanding of liver injury mechanisms, new strategies for treatment are now being explored, including siRNA technology, molecules to modulate secretion, and enhancers of proteolysis.

Liver transplantation for rare liver diseases and rare indications for liver transplant

Liver transplantation (LT) is currently considered the gold standard treatment for end-stage liver failure. Compared to the first decades of its use, LT is associated with lower comorbidity and mortality, with a 5-year survival over 70%. Worldwide, liver cirrhosis and hepatocellular carcinoma represent the major indications to LT. However, almost 1% of LT is performed for rare diseases or rare indications, which include non-hepatocellular malignancy, vascular disorders, metabolic and congenital liver disorders. These diseases can lead to hepatocellular necrosis, biliary tree abnormality and/or hepatomegaly. Most of these diseases are not associated with liver failure but in highly selected patients, LT represent an effective therapy improving the overall survival and quality of life. Rare indications for LT often overlap with rare diseases. However, rare LT indications for non-rare diseases are rising in the last decades, especially for benign primary liver tumor, colon rectal liver metastasis, neuroendocrine liver metastasis, and cholangiocarcinoma (CCA). Non-rare diseases with rare indication for LT and rare adult disease with an indication for LT are categorized and discussed in detail, focusing on some disorders for which the literature provides a more definitive evidence base. Early referral to a transplant center is encouraged to provide an effective therapeutic option in these non-standard indications for LT.

Alpha1-Antitrypsin Deficiency: A Cause of Chronic Liver Disease

Alpha1-antitrypsin deficiency (A1ATD) is an inherited cause of chronic liver disease. It is inherited in an autosomal codominant pattern with each inherited allele expressed in the formation of the final protein, which is primarily produced in hepatocytes. The disease usually occurs in pediatric and elderly populations. The disease occurs with the accumulation of abnormal protein polymers within hepatocytes that can induce liver injury and fibrosis. It is a commonly under-recognized and underdiagnosed condition. Patients diagnosed with the disease should be regularly monitored for the development of liver disease. Liver transplant is of proven benefit in A1ATD liver disease.

Diagnosis and treatment of lung disease associated with alpha one-antitrypsin deficiency: A position statement from the Thoracic Society of Australia and New Zealand

AATD is a common inherited disorder associated with an increased risk of developing pulmonary emphysema and liver disease. Many people with AATD-associated pulmonary emphysema remain undiagnosed and therefore without access to care and counselling specific to the disease. AAT augmentation therapy is available and consists of i.v. infusions of exogenous AAT protein harvested from pooled blood products. Its clinical efficacy has been the subject of some debate and the use of AAT augmentation therapy was recently permitted by regulators in Australia and New Zealand, although treatment is not presently subsidized by the government in either country. The purpose of this position statement is to review the evidence for diagnosis and treatment of AATD-related lung disease with reference to the Australian and New Zealand population. The clinical efficacy and adverse events of AAT augmentation therapy were evaluated by a systematic review, and the GRADE process was employed to move from evidence to recommendation. Other sections address the wide range of issues to be considered in the care of the individual with AATD-related lung disease: when and how to test for AATD, changing diagnostic techniques, monitoring of progression, disease in heterozygous AATD and pharmacological and non-pharmacological therapy including surgical options for severe disease. Consideration is also given to broader issues in AATD that respiratory healthcare staff may encounter: genetic counselling, patient support groups, monitoring for liver disease and the need to establish national registries for people with AATD in Australia and New Zealand.

Alpha1-Antitrypsin Deficiency: Transition of Care for the Child With AAT Deficiency into Adulthood

IMPORTANCE

Alpha1-antitrypsin (AAT) deficiency is a common, but an underdiagnosed genetic condition, affecting 1 in 1500 individuals. It can present insidiously with liver disease in children. Although clinical practice guidelines exist for the management of AAT deficiency, especially with regards to pulmonary involvement, there are no published recommendations that specifically relate to the management of the liver disease and monitoring for lung disease associated with this condition, particularly in children.

OBJECTIVE

To review the literature on the management of AAT deficiency-associated liver disease in adults and children.

EVIDENCE REVIEW

A systematic search for articles indexed in PubMed and published was undertaken. Some earlier selected landmark references were included in the review. Search terms included: "alpha1-antitrypsin deficiency"; "liver disease"; "end-stage liver disease"; "liver transplantation" and "preventative management". Recommendations for the management of children with suspected or confirmed AAT deficiency were made according to the Strength of Recommendation Taxonomy scale.

FINDINGS

Liver complications arising from AAT deficiency result from the accumulation of mutated AAT protein within hepatocytes. Liver disease occurs in 10% of children, manifested by cholestasis, pruritus, poor feeding, hepatomegaly, and splenomegaly, but the presentation is highly variable. A diagnostic test for AAT deficiency is recommended for these children. Baseline liver function tests should be obtained to assess for liver involvement; however, the only curative treatment for AAT deficiency-associated liver disease is organ transplantation. Conclusion and Relevance: There should be a greater vigilance for AAT deficiency testing among pediatricians. Diagnosis should prompt assessment of liver involvement. Children with AATdeficiency- associated liver disease should be referred to a liver specialist and monitored throughout their lifetimes for the symptoms of AAT-deficiency-related pulmonary involvement.

Respiratory Complications Before and After Liver Transplant

Respiratory complications before and after liver transplant are common, diverse, and potentially have a negative impact on patient outcomes. In this review, we discuss the most frequent respiratory conditions that patients may develop in the perioperative period. Their prevention and/or treatment may help to maximize the benefit these patients may derive from liver transplant. This review examines diagnostic and therapeutic approaches to these complications for hepatologists, surgeons, and critical care physicians.

Systematic review: the natural history of alpha-1 antitrypsin deficiency, and associated liver disease

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is estimated to affect three million people worldwide. It causes liver disease in a proportion of carriers of the PiS and PiZ allele due to the formation and retention of polymers within the endoplasmic reticulum of hepatocytes. The reason for this selective penetrance is not known. Although clinical trials are underway, liver transplantation is the only effective treatment for liver disease due to AATD.

AIMS

To report the prevalence and natural history of liver disease among individuals with AATD, and assess the outcomes of liver transplantation through systematic review.

METHODS

A comprehensive search was conducted across multiple databases. Two independent authors selected the articles and assessed bias using the Newcastle-Ottawa Scale. Data were pooled for analysis, where comparable outcomes were reported.

RESULTS

Thirty-five studies were identified related to disease progression and 12 for the treatment of AATD. Seven per cent of children were reported to develop liver cirrhosis, with 16.5% of individuals presenting in childhood requiring liver transplantation. Of those surviving to adulthood, 10.5% had liver cirrhosis and 14.7% required transplantation. Liver transplantation was the only effective treatment reported and outcomes compare favourably to other indications, with 5-year survival reported as over 90% in children and over 80% in adults.

DISCUSSION

The clinical course of liver disease in individuals with AATD remains poorly understood, but affects about 10% of those with AATD. More research is required to identify those patients at risk of developing liver disease at an early stage, and to provide alternative treatments to liver transplantation.

Managing panniculitis in alpha-1 antitrypsin deficiency: Systematic review of evidence behind treatment

AIM

To systematically review literature for management of alpha-1 antitrypsin deficiency (AATD) panniculitis.

METHODS

Multiple databases were searched using combinations of pertinent terms. Articles were selected describing panniculitis treatment in patients with AAT < 11 μmol and/or PiZZ genotype, with no language limitation. All relevant articles were accessed in full text. Independent review of abstracts and full manuscripts was conducted by 2 reviewers, and quality assessment by one reviewer (checked by a second). Data extraction was conducted by one reviewer (checked by a second). Narrative synthesis only was conducted, as data were unsuitable for meta-analysis.

RESULTS

Thirty-two case reports and 4 case series were found. Augmentation therapy (infusions of plasma-derived AAT) was the most successful, with complete resolution of symptoms in all patients. Dapsone is a less expensive option, and it achieved clinical resolution in 62% of patients, but it is very poorly tolerated. Among other single-agent antibiotics, doxycycline was the most successful with complete clinical resolution seen in 33% of patients. Immunosuppressants were largely unsuccessful; 80% of patients exhibited no response. Liver transplantation and therapeutic plasma exchange displayed complete resolution in 66% of patients. Other strategies, such as non-steroidal anti-inflammatory drugs or antibiotics other than dapsone did not show sufficient response rates to recommend their use. Authors note the risk of bias imposed by the type of evidence (case reports, case series) available in this field.

CONCLUSION

Dapsone is the recommended first line therapy for AATD panniculitis, followed by augmentation therapy. Plasma exchange may be an alternative in the setting of rapidly progressive disease.

Liver Disease in Alpha-1 Antitrypsin Deficiency: Current Approaches and Future Directions

Purpose of Review

The aim of the study is to review the liver disease caused by alpha-1 antitrypsin deficiency (A1ATD), including pathogenesis, epidemiology, diagnostic testing, and recent therapeutic developments.

Recent Findings

Therapeutic approaches target several intracellular pathways to reduce the cytotoxic effects of the misfolded mutant globular protein (ATZ) on the hepatocyte. These include promoting ATZ transport out of the endoplasmic reticulum (ER), enhancing ATZ degradation, and preventing ATZ globule-aggregation.

Summary

A1ATD is the leading genetic cause of liver disease among children. It is a protein-folding disorder in which toxic insoluble ATZ proteins aggregate in the ER of hepatocytes leading to inflammation, fibrosis, cirrhosis, and increased risk of hepatocellular carcinoma. The absence of the normal A1AT serum protein also predisposes patients to pan lobar emphysema as adults. At this time, the only approved therapy for A1ATD-associated liver disease is orthotopic liver transplantation, which is curative. However, there has been significant recent progress in the development of small molecule therapies with potential both to preserve the native liver and prevent hepatotoxicity.

Liver Transplantation in Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin (AAT) deficiency is a common inherited metabolic disorder caused by a point mutation in the SERPIN1A gene. A small portion of homozygous PI*ZZ individuals develop severe liver disease that requires liver transplantation. Posttransplant survival is excellent. The largest burden of advanced liver disease lies within the adult population rather than children. Evaluation of lung function in adults before transplant is essential because of the underlying risk for chronic obstructive pulmonary disease. Post-liver transplantation lung function should also be monitored for decline. Although uncommon, cases of simultaneous lung and liver transplant for AAT deficiency have been reported.

Therapeutic Options in Alpha-1 Antitrypsin Deficiency: Liver Transplantation

Alpha-1 antitrypsin deficiency is the commonest genetic condition leading to liver transplantation in childhood. It remains unclear why only a minority of individuals carrying homozygous PiZ phenotype has liver disease, but also why of those only about a quarter develops end stage liver disease, requiring liver transplantation. This intervention has now become routine worldwide with 1-year patient survival rates well above 90%. As for all autosomal recessive conditions liver donation from anonymous cadaveric sources is preferred to living related parental donors, due to their presumed heterozygous state.

Current and Future Burden of Chronic Nonmalignant Liver Disease

Disease burden is an important indicator of the state of health of a population. It can be measured as the frequency (eg, incidence and prevalence) of a condition or its effects including fatal and non-fatal health loss from disease (eg, disability-adjusted life years) as well as the financial costs (eg, direct healthcare costs and indirect healthcare expenditures related to lost income because of premature death). Accurate disease burden information is essential for policy-making such as prioritization of health interventions and allocation of resources. Chronic liver disease (CLD) causes substantial health and economic burden in the United States, where nearly 2 million deaths annually are attributable to CLD. In the recent past, overall mortality rate of CLD has been increasing. Viral hepatitis and alcoholic liver disease are thought to be the most common etiologies of chronic liver diseases. More recently, the prevalence of nonalcoholic fatty liver disease is rapidly increasing, and nonalcoholic steatohepatitis has become a leading indication for liver transplantation. In this article, we assemble available data on the burden of CLD in the United States, focusing on nonmalignant complications, whereas the impact on mortality and healthcare expenses of hepatocellular carcinoma, an important consequence of CLD, is discussed elsewhere.

Therapeutic targeting of misfolding and conformational change in α1-antitrypsin deficiency

Misfolding and conformational diseases are increasing in prominence and prevalence. Both misfolding and ‘postfolding’ conformational mechanisms can contribute to pathogenesis and can coexist. The different contexts of folding and native state behavior may have implications for the development of therapeutic strategies. α1-antitrypsin deficiency illustrates how these issues can be addressed with therapeutic approaches to rescue folding, ameliorate downstream consequences of aberrant polymerization and/or maintain physiological function. Small-molecule strategies have successfully targeted structural features of the native conformer. Recent developments include the capability to follow solution behavior of α1-antitrypsin in the context of disease mutations and interactions with drug-like compounds. Moreover, preclinical studies in cells and organisms support the potential of manipulating cellular response repertoires to process misfolded and polymer states.

[Hepatic involvement in hereditary alpha-1-antitrypsin deficiency]

Apha-1-antitrypsin deficiency is an autosomal recessive genetic disorder seen in all races. The molecular defect is a specific mutation of the SERPINA1 gene leading to synthesis of an abnormal protein (alpha-1-antitrypsin Z) that cannot be secreted and polymerizes in the endoplasmic reticulum of hepatocytes. The inter-individual variability in the responses to intracellular stress induced by the accumulation of abnormal polymers and the mechanisms allowing their degradation is, without doubt, responsible for the different clinical manifestations of the disease. The disease affects the liver where the abnormal protein is synthesized and the lung, which is its place of action. Liver involvement is well recognized in homozygous infants of the phenotype ZZ. In this situation the disease may present a varying picture from neonatal cholestasis (about 15% of neonatal defects) to cirrhosis. However, evolution towards cirrhosis affects less than 3% of infants with the ZZ phenotype and it is preceded in 80% of cases by neonatal cholestasis. In adolescents or adults the manifestations associated with alpha-1-antitrypsin deficiency are usually limited to biochemical abnormalities but may lead to cirrhosis or hepatocellular carcinoma. The hepatic disorder and its complications are treated symptomatically though the pulmonary involvement may benefit from substitution treatment. More specific treatments targeting the molecular and cellular abnormalities are the subject of research.

Outcomes for recipients of liver transplantation for alpha-1-antitrypsin deficiency–related cirrhosis

Alpha-1-antitrypsin (AAT) deficiency is a rare genetic disease caused by an abnormal production of the serine protease inhibitor AAT. Liver transplantation (LT) cures cirrhosis caused by AAT deficiency and restores the normal production of AAT. There are few reports on the post-LT outcomes of patients with AAT deficiency. The aim of this study was to determine the characteristics and outcomes of patients undergoing LT for AAT deficiency at 3 large transplant centers. All patients undergoing LT at these 3 transplant centers from 1987 to 2012 for AAT deficiency (ZZ or SZ phenotype) were included. The most recent 50 patients with the MZ phenotype were also included for comparison. Data were collected retrospectively from internal databases and medical records. Seventy-three patients (50 with the ZZ phenotype and 23 with the SZ phenotype)underwent LT. The mean age was 52.8 years, and the majority of the patients (75.6%) were men. Before LT, serum AAT levels were lower for the ZZ patients versus the SZ patients (28.3 versus 58.0 mg/dL, P < 0.001). More than 40% of the SZ patients had an additional liver disease, whereas 8% in the ZZ group and 90% in the MZ group did. Before LT, there was no significant difference in pulmonary function between the ZZ and SZ groups. Seventeen patients (all with ZZ phenotype)had pulmonary function tests performed before and after LT. The forced expiratory volume in 1 second (FEV1) continued to decline for the majority. The 1-, 3-, 5-, and 10-year post-LT survival rates were 86%, 83%, 80%, and 72%, respectively, for the ZZ patients and 91%, 86%, 79%, and 79%, respectively, for the SZ patients. In conclusion, survival after LT for patients with ZZ or SZ AAT deficiency is excellent. Despite the normalization of AAT levels after LT, FEV1 continues to decline unexpectedly after LT in some ZZ and SZ patients.

Monogenic diseases that can be cured by liver transplantation

While the prevalence of most diseases caused by single-gene mutations is low and defines them as rare conditions, all together, monogenic diseases account for approximately 10 in every 1000 births according to the World Health Organisation. Orthotopic liver transplantation (LT) could offer a therapeutic option in monogenic diseases in two ways: by substituting for an injured liver or by supplying a tissue that can replace a mutant protein. In this respect, LT may be regarded as the correction of a disease at the level of the dysfunctional protein. Monogenic diseases that involve the liver represent a heterogeneous group of disorders. In conditions associated with predominant liver parenchymal damage (i.e., genetic cholestatic disorders, Wilson's disease, hereditary hemochromatosis, tyrosinemia, α1 antitrypsin deficiency), hepatic complications are the major source of morbidity and LT not only replaces a dysfunctional liver but also corrects the genetic defect and effectively cures the disease. A second group includes liver-based genetic disorders characterised by an architecturally near-normal liver (urea cycle disorders, Crigler-Najjar syndrome, familial amyloid polyneuropathy, primary hyperoxaluria type 1, atypical haemolytic uremic syndrome-1). In these defects, extrahepatic complications are the main source of morbidity and mortality while liver function is relatively preserved. Combined transplantation of other organs may be required, and other surgical techniques, such as domino and auxiliary liver transplantation, have been attempted. In a third group of monogenic diseases, the underlying genetic defect is expressed at a systemic level and liver involvement is just one of the clinical manifestations. In these conditions, LT might only be partially curative since the abnormal phenotype is maintained by extrahepatic synthesis of the toxic metabolites (i.e., methylmalonic acidemia, propionic acidemia). This review focuses on principles of diagnosis, management and LT results in both paediatric and adult populations of selected liver-based monogenic diseases, which represent examples of different transplantation strategies, driven by the understanding of the expression of the underlying genetic defect.

Pulmonary contraindications, indications and MELD exceptions for liver transplantation: a contemporary view and look forward

Pulmonary concerns in liver transplant candidates have intraoperative and outcome implications. Evolving MELD exception policies address transplant priority for problems such as hepatopulmonary syndrome, portopulmonary hypertension, and hemorrhagic hereditary telangiectasia. Other pulmonary issues such as refractory hepatic hydrothorax, advanced chronic obstructive lung disease (including alpha-1 antitrypsin deficiency) and indeterminate pulmonary nodules may affect liver transplant consideration. Herein, we discuss current pulmonary-related contraindications, indications and MELD exception policies for liver transplantation, suggesting future considerations.

Diagnosis and management of patients with α1-antitrypsin (A1AT) deficiency

Alpha(1)-antitrypsin (A1AT) deficiency is an autosomal codominant disease that can cause chronic liver disease, cirrhosis, and hepatocellular carcinoma in children and adults and increases risk for emphysema in adults. The development of symptomatic disease varies; some patients have life-threatening symptoms in childhood, whereas others remain asymptomatic and healthy into old age. As a result of this variability, patients present across multiple disciplines, including pediatrics, adult medicine, hepatology, genetics, and pulmonology. This can give physicians the mistaken impression that the condition is less common than it actually is and can lead to fragmented care that omits critical interventions commonly performed by other specialists. We sought to present a rational approach for hepatologists to manage adult patients with A1AT deficiency.

Is the patient a candidate for liver transplantation?

Identifying whether someone is a good candidate for liver transplantation is a complex process that requires a team approach. There are several medical and psychosocial considerations involved, each of which is thoroughly explored during the evaluation process. Both the indications and contraindications to transplantation can change over time, reflecting advances in understanding of, and ability to treat, certain disease processes. Ultimately, the goal of liver transplantation remains to provide a survival benefit to those with acute or chronic liver diseases.

Why has it been so difficult to prove the efficacy of alpha-1-antitrypsin replacement therapy? Insights from the study of disease pathogenesis

Alpha-1-antitrypsin is the most abundant circulating protease inhibitor. It is mainly produced by the liver and secreted into the circulation where it acts to prevent excessive proteolytic damage in the lungs by the enzyme neutrophil elastase. The most common severe deficiency allele is the Z mutation, which causes the protein to self-associate into ordered polymers. These polymers accumulate within hepatocytes to cause liver damage. The resulting lack of circulating α₁-antitrypsin predisposes the Z homozygote to proteolytic lung damage and emphysema. Other pathways may also contribute to the development of lung disease. In particular, polymers of Z α₁-antitrypsin can form within the lung where they act as a pro-inflammatory stimulus that may exacerbate protease-mediated lung damage. Researchers recognized in the 1980s that plasma α₁-antitrypsin levels could be restored by intravenous infusions of purified human protein. Alpha-1-antitrypsin replacement therapy was introduced in 1987 but subsequent clinical trials have produced conflicting results, and to date there remains no widely accepted clinical evidence of the efficacy of α₁-antitrypsin replacement therapy. This review addresses our current understanding of disease pathogenesis in α₁-antitrypsin deficiency and questions why this treatment in isolation may not be effective. In particular it discusses the possible role of α₁-antitrypsin polymers in exacerbating intrapulmonary inflammation and attenuating the efficacy of α₁-antitrypsin replacement therapy.

Paediatric liver transplantation for metabolic disorders. Part 2: Metabolic disorders with liver lesions

Liver based metabolic disorders account for 10 to 15% of the indications for paediatric liver transplantation. In the last three decades, important progress has been made in the understanding of these diseases, and new therapies have emerged. Concomitantly, medical and surgical innovations have lead to improved results of paediatric liver transplantation, patient survival nowadays exceeding 80% 10 year after surgery with close to normal quality of life in most survivors. This review is a practical update on medical therapy, indications and results of liver transplantation, and potential future therapies, for the main liver based metabolic disorders in which paediatric liver transplantation may be considered. Part 1 focuses on metabolic based liver disorders without liver lesions, and part 2 on metabolic liver diseases with liver lesions.

[Alpha1-antitrypsin deficiency]

Alpha(1)-antitrypsin deficiency is characterized by a pathologic reduction of the serum concentration of alpha(1)-antitrypsin, the most important antiprotease in man. It is one of the most common hereditary diseases in Caucasians. Approximately 2% of obstructive airway diseases are caused by alpha(1)-antitrypsin deficiency. Patients above 35 years may develop lung emphysema, especially in the lower lobes. Symptoms are those of chronic obstructive pulmonary disease such as cough, sputum expectoration, and progressive dyspnoea. Patients with homozygous defect often develop cholestatic hepatitis in the neonatal period. However, only few adult patients develop chronic liver disease up to liver cirrhosis with an elevated risk for malignant liver tumors. The diagnostic hallmark is the reduced serum concentration of alpha(1)-antitrypsin while genetic testing proves the defect. An early recognition of the disease is decisive for prophylactic and therapeutic measures. Smoking should be stopped immediately. Treatment of lung disease includes physiotherapy, antiobstructive and antiinflammatory medication, augmentation with human alpha(1)-antitrypsin and lung surgery including lung transplantation. Liver toxins should be avoided. Besides experimental therapeutic approaches, liver disease can only be treated by liver transplantation.

Inherited metabolic disease of the liver

PURPOSE OF REVIEW

Progress in the dissection of the molecular pathogenesis of most prevalent inherited liver diseases such as hereditary hemochromatosis, Wilson's disease, and alpha1-antitrypsin deficiency is continuing. This review highlights recent achievements that have clarified defective molecular pathways and shed new lights on the complex interplay of genetic and environmental factors in determining disease phenotype. This advancement paves the way for development of new strategies to diagnose and cure metabolic liver diseases.

RECENT FINDINGS

Hepcidin, the iron hormone that is defective in hemochromatosis, is controlled not only by iron signals but also by a number of circulatory and membrane-associated regulators. Serum and urinary hepcidin can be now measured. New studies have provided important information on variable clinical expressivity of the genetic defect in hemochromatosis. The molecular and cellular events that accompany Wilson's disease and alpha-1-antitrypsin deficiency are being elucidated. In both, an unexpected pathogenic link with early metabolic abnormality in lipid or glycogen metabolism has emerged. Interference with apoptotic pathways may offer new therapeutic tools to prevent liver disease progression and acute liver failure associated with inherited metabolic diseases of the liver.

SUMMARY

The field of inherited diseases of the liver is rapidly evolving. Understanding molecular pathogenesis of these disorders is improving our ability to diagnose and treat them. The most recent findings are detailed in this review.