Abstract
Background and Aim. Neonatal hemochromatosis (NH) is characterised by severe liver injury and extrahepatic siderosis sparing the reticuloendothelial system. Its aetiology is obscure, although it has been proposed as an alloimmune disease, resulting from immunological reaction to self-antigens (alloantigens) which the body recognizes as foreign. We studied an infant with NH and his mother whose sera contained antimitochondrial antibody (AMA), the hallmark of primary biliary cirrhosis (PBC). Material and Methods. To investigate the origin of AMA in the infant, we studied isotype distributions in serum from the mother and infant. Serum samples were obtained at diagnosis of NH, after liver transplantation (LT; age 1 month), and over the ensuing 17 months. Results. At NH diagnosis, infant and maternal serum contained AMA of the IgG isotype, predominantly of the G3 and G1 subclasses. AMA strongly reacted against the pyruvate dehydrogenase complex E2 subunit (PDC-E2), the major PBC-specific AMA autoantigen. Anti-PDC-E2 responses in both infant and mother declined over time, being present 2 months after LT (mother and child) and absent 10 months later (mother) and 17 months later (child). Conclusion. The association of maternally transferred IgG1 and IgG3 subclass AMA with the appearance of liver damage in an infant with NH may suggest a causal link between antibody and liver damage.
Highlights
Neonatal haemochromatosis (NH) is a rare condition of unknown aetiology characterised by perinatal liver failure and extrahepatic siderosis sparing the reticuloendothelial system [1, 2]
We investigated an infant with NH whose serum contained antimitochondrial antibody (AMA), the hallmark of primary biliary cirrhosis (PBC), a disease with a striking (>95%) female preponderance typically affecting middleaged women [20, 21]
All the evidence indicates that his AMA was of maternal origin, since it belonged to the placenta-crossing IgG class and showed a similar IgG3 and IgG1 pattern in mother and baby [29, 30]
Summary
Neonatal haemochromatosis (NH) is a rare condition of unknown aetiology characterised by perinatal liver failure and extrahepatic siderosis sparing the reticuloendothelial system [1, 2]. Autoantibodies of maternal origin, such as anti-Ro and antiLa, have been described in some children with NH [3, 13,14,15,16,17]. The relevance of these antibodies, which are not liver specific [18], to the pathogenic process in NH is unclear, they have been associated with liver disease in rare cases [19]. At NH diagnosis, infant and maternal serum contained AMA of the IgG isotype, predominantly of the G3 and G1 subclasses. The association of maternally transferred IgG1 and IgG3 subclass AMA with the appearance of liver damage in an infant with NH may suggest a causal link between antibody and liver damage
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