High prevalence of α-1-antitrypsin heterozygosity in children with chronic liver disease

OBJECTIVE: α-1-antitrypsin (A1AT) deficiency is the most common genetic cause of liver disease in children; however, the role of polymorphic heterogeneity in the A1AT gene as a modifier of other forms of pediatric liver disease is not clear. We hypothesized that non-M A1AT allele variants are more common in children with chronic liver disease than in the general population. METHODS: A retrospective, single-center study was performed in which A1AT phenotypes were obtained by reviewing charts of children with chronic liver disease. Chi-square analysis was used to compare allele frequencies in the population of children with liver disease with published epidemiologic data and to compare allele frequencies among disease subgroups. RESULTS: The frequency of A1AT Z and other alleles was increased in children with chronic liver disease (n = 241) when compared with the published reference database (P < 0.001). This increase remained significant when the population was divided into disease subsets: biliary atresia (n = 67) and other liver disease (n = 174) (P < 0.001 for both). Among children with biliary atresia referred for liver transplant evaluation, the presence of a non-M allele was associated with a lower mean age at transplant listing than the MM phenotype (235 vs 779 days, P = 0.036) and more frequent loss of native liver by 24 months of age (90% vs 65%, P = 0.04). CONCLUSIONS: A1AT non-M alleles are more frequent in children with chronic liver disease than in the general population. We speculate that these non-M alleles may act as genetic modifiers in pediatric liver disease in general and modulate disease progression in children with biliary atresia in particular.