Genetically determined low C4: a predisposing factor to autoimmune chronic active hepatitis

Lancet. 1985 Aug 10;2(8450):294-8. doi: 10.1016/s0140-6736(85)90348-4.

Abstract

Of 26 patients with autoimmune chronic active hepatitis (CAH) starting in childhood 18 (69%) had low C4 and 5 (19%) had low C3 serum levels. Impaired hepatic synthesis and immune-consumption were unlikely since transferrin levels were normal in all patients, albumin levels were persistently low in only 3, and only 3 had raised levels of activation fragment C3d. C4d was normal in all patients studied. In the families of 12 probands with low C4, 7 parents had low C4 and 2 had levels which were at the lower limit of normal. 5 of 10 siblings from 5 families had low C4. These results suggest that low C4 levels in CAH are genetically determined. C4 phenotyping in 20 patients and in 26 parents showed that 90% and 81%, respectively, had null allotypes at either the C4A or C4B locus compared with 59% in controls, indicating that defective expression of structural genes may contribute to the observed C4 deficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Autoimmune Diseases / blood
  • Autoimmune Diseases / genetics*
  • Child
  • Child, Preschool
  • Complement C3 / deficiency
  • Complement C3 / genetics
  • Complement C4 / deficiency
  • Complement C4 / genetics*
  • Disease Susceptibility
  • Female
  • Genes
  • Hepatitis, Chronic / blood
  • Hepatitis, Chronic / genetics*
  • Hepatitis, Chronic / immunology
  • Humans
  • Male
  • Phenotype
  • Polymorphism, Genetic

Substances

  • Complement C3
  • Complement C4