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Frequency and significance of phenotypes for alpha1-antitrypsin deficiency in type 1 autoimmune hepatitis
1Division of Gastroenterology and Hepatology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA.
Insights
Alpha-1 antitrypsin deficiency phenotypes are common in autoimmune hepatitis type 1 but do not affect patient outcomes. These variant phenotypes may be comorbid factors in nonalcoholic steatohepatitis.
Area of Science:
- Hepatology
- Medical Genetics
Background:
- Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder that can lead to liver and lung disease.
- Its prevalence and clinical significance in autoimmune hepatitis (AIH) are not well-established.
Purpose of the Study:
- To determine the frequency of alpha-1 antitrypsin deficiency (AATD) variant phenotypes in patients with type 1 autoimmune hepatitis (AIH).
- To assess the clinical and prognostic importance of these phenotypes in AIH.
- To compare AATD phenotype frequency in AIH with other chronic liver diseases.
Main Methods:
- Genotyping for alpha-1 antitrypsin (AAT) phenotypes was performed on 181 Caucasian patients with type 1 AIH.
- A control group of 303 Caucasian patients with other chronic liver diseases was also evaluated.
- Phenotype frequencies and clinical outcomes, including response to corticosteroid therapy, were compared between groups.
Main Results:
- Twelve percent (21/181) of AIH patients had heterozygous AAT deficiency phenotypes (MS and MZ).
- These patients were clinically indistinguishable from those with normal AAT phenotypes and showed similar outcomes after corticosteroid treatment.
- Variant AAT phenotypes were found in 11% of patients with other chronic liver diseases.
- Nonalcoholic steatohepatitis patients had a significantly higher frequency of AAT deficiency phenotypes (20%) compared to chronic hepatitis C patients (7%).
Conclusions:
- Alpha-1 antitrypsin deficiency phenotypes are common in type 1 autoimmune hepatitis but lack clinical or prognostic significance.
- Variant AAT phenotypes may represent comorbid factors in specific liver diseases like nonalcoholic steatohepatitis.
Abstract:
To evaluate the frequency and significance of alpha1-antitrypsin deficiency in type 1 autoimmune hepatitis, 181 Caucasian patients were assessed for variant phenotypes. Three hundred three Caucasian patients with various other chronic liver diseases were similarly evaluated. Twenty-one of the 181 patients (12%) had heterozygous deficiencies, including the MS (6%) and MZ (6%) phenotypes. These patients were indistinguishable from those with normal phenotypes. Immediate outcomes after corticosteroid therapy were also similar in both groups. Variant phenotypes were present in 34 of the 303 patients with other chronic liver diseases (11%). Patients with nonalcoholic steatohepatitis had a significantly greater frequency of deficiency phenotypes than patients with chronic hepatitis C (20% vs 7%, P = 0.03). In conclusion, deficiency phenotypes are common in type 1 autoimmune hepatitis and they have no clinical or prognostic importance. In certain liver diseases, such as nonalcoholic steatohepatitis, variant phenotypes may be comorbid factors.