Novel Alpha 1-Antitrypsin Variant Linked to Early-Onset Liver Disease

A newly discovered genetic variant of Alpha 1-Antitrypsin Deficiency (AATD) may provide important insights into early-onset liver disease, according to a study published in the Orphanet Journal of Rare Diseases.

ATTD is a rare genetic disorder caused by mutations in the SERPINA1 gene, which produces Alpha 1-Antitrypsin (AAT), a protein that protects the lungs and other organs. When these mutations occur, individuals become predisposed to both lung and liver damage.

The research team identified a previously undocumented SERPINA1 variant in two unrelated families from southeastern France. This variant, named PiMarseille, results from a combination of the common PiZ allele with a rare variant known as PiBristol.

"PiMarseille has been associated with early-onset liver disease in childhood," the researchers noted, highlighting the variant's clinical significance.

Molecular Characteristics

To understand how this new variant affects the body, the research team conducted molecular and functional characterization studies. Their findings reveal that PiMarseille shares pathogenic properties of both the PiZ and PiBristol variants.

Specifically, the researchers observed that the mutant protein is retained within the endoplasmic reticulum of cells as aggregates, rather than being properly secreted. The body attempts to manage these aggregates through two cellular cleanup mechanisms—the autophagy and proteasome pathways—but this accumulation can damage liver cells over time.

Proteomic Insights

The research team went further by analyzing the complete protein profile (proteome) of liver samples containing the PiMarseille variant. Their proteomic analysis revealed that the neutrophil degranulation pathway—an immune system process—is particularly disrupted in these samples.

Interestingly, when compared to other AAT genotypes, the proteomic profile of PiMarseille most closely resembles that of the PiBristol variant, providing clues about its disease mechanism.

These findings contribute to our understanding of how different AAT variants affect liver health and may eventually lead to more targeted treatments for people with AATD, particularly those with early-onset liver manifestations.

For individuals with albinism who might also carry rare genetic conditions like AATD, this research underscores the importance of comprehensive genetic evaluation when unusual symptoms appear, especially in pediatric cases presenting with liver dysfunction.