Alpha-1 antitrypsin deficiency-associated liver disease (AATD-LD) remains underrecognized despite its significant contribution to morbidity and mortality in adults with the PiZZ genotype. Lack of standardized definitions, diagnostic criteria, and staging impedes timely diagnosis and therapeutic development. To address these gaps, a multi-disciplinary expert panel convened under the auspices of the American Gastroenterological Association in collaboration with the American Association for the Study of Liver Diseases, European Association for the Study of the Liver, and Alpha-1 Foundation to develop consensus recommendations for nomenclature, diagnosis, staging, and clinical trial endpoints in AATD-LD.

Individuals heterozygous for alpha-1 antitrypsin deficiency (AATD) have one copy of the normal “M” allele and one copy of an abnormal allele (“Z”, “S”, or another variant) in the SERPINA1 gene. Historically, evidence has been lacking to support the concept that heterozygotes are at increased risk for liver and/or lung complications compared to individuals homozygous for the M allele. However, growing evidence suggests that inheritance of a single Z allele increases the risk of disease in some individuals. The Alpha-1 Foundation convened a workshop on October 27, 2023, in Bethesda, Maryland that included stakeholders from the research, pharmaceutical, and patient communities. The focus of the meeting was to describe and assess what is known about the relative risks of liver and/or lung disease for heterozygotes and to identify future avenues of research into disease mechanisms and clinical phenotypes in MZ heterozygotes.

Sarcopenia occurs in pediatric chronic liver disease, although the prevalence and contributing factors in genetic intrahepatic cholestasis are not well-described. The objective of this study was to measure muscle mass in school-aged children with genetic intrahepatic cholestasis and assess relationships between sarcopenia, clinical variables, and outcomes.

Alpha-antitrypsin (AAT) deficiency results from carriage of a homozygous “Z” mutation (proteinase inhibitor [PI] ZZ). The Z allele produces a mutant AAT protein called Z-AAT, which accumulates in hepatocytes and can lead to progressive liver disease and fibrosis. This open-label, phase 2 trial investigated the safety and efficacy of fazirsiran, an RNA interference therapeutic, in patients with liver disease associated with AAT deficiency.

Liver disease in homozygous ZZ alpha-1 antitrypsin (AAT) deficiency occurs due to the accumulation of large quantities of AAT mutant Z protein polymers in the liver. The mutant Z protein folds improperly during biogenesis and is retained within the hepatocytes rather than appropriately secreted. These intracellular polymers trigger an injury cascade, which leads to liver injury. However, the clinical liver disease is highly variable and not all patients with this same homozygous ZZ genotype develop liver disease. Evidence suggests that genetic determinants of intracellular protein processing, among other unidentified genetic and environmental factors, likely play a role in liver disease susceptibility. Advancements made in development of new treatment strategies using siRNA technology, and other novel approaches, are promising, and multiple human liver disease trials are underway.