CHRONIC ACTIVE AUTOIMMUNE HEPATITIS IN CHILDREN - STRONG ASSOCIATION WITH A PARTICULAR HLA-DR6 (DRB1-ASTERISK-1301) HAPLOTYPE

The association of HLA antigens and type I or ''lupoid'' CAH-C was inv estigated in a population of 52 Argentinian Caucasoid patients. When c ompared with a population of normal individuals of the same ethnic gro up (n = 197), a significant increase of HLA-DR6 was observed (68.6% in patients vs 17.3% in controls; RR = 12.3, chi(2) = 52.4, P-c = 0.0000 1). DNA typing showed that the HLA-DRB11301 allele was present in 32 out of 33 HLA-DR6 patients (66. 6% of all the C-CAH patients vs 10.5% in controls; RR = 16.2, chi(2) = 111.3, P-c 0.00001). Analysis of HLA- DQB1 alleles also showed a significant increase of DQB10603 (RR = 15. 4, chi(2) = 106.5, P-c = 0.00001), an allele found in strong linkage d isequilibrium with DRB11301. The association of CAH-C with this parti cular HLA-DRG haplotype has not been previously described for the adul t onset CAH. This different HLA predisposition, together with the fact that extrahepatic autoimmune diseases occur frequently only in the ad ult form of the disease, suggest that the immunopathogenic mechanisms involved in the development of these diseases may be different.