title: Evidence of a genetic basis for the different geographic occurrences of liver/kidney microsomal antibody type 1 in hepatitis C.
abstract: Antibodies to liver/kidney microsome type 1 occur in Italian patients with hepatitis C, but rarely develop in North American patients. Our goals were to compare the frequencies of the HLA markers associated with autoimmune expression in Italian and North American patients with chronic hepatitis C and to determine genetic bases for regional differences in antibody production. HLA B8, DR3, DR4, DR7, DR11, DR13, DQ2, and the B8-DR3-DQ2 haplotype were determined by microlymphocytotoxicity and polymerase chain reaction in 105 Italian patients (50 with microsomal antibodies), 100 North American patients (none with microsomal antibodies), and Italian and North American healthy control subjects. Italian patients with microsomal antibodies differed from North American patients without these antibodies by having a higher frequency of HLA DR7 (54% vs. 27%, P=0.002). HLA DR7 occurred more frequently in seropositive Italian patients than in seronegative counterparts (54% vs. 11% P < 0.0001), Italian healthy control subjects (54% vs. 29%, P=0.0009), and North American healthy control subjects (54% vs. 19%, P < 0.0001). The frequency of HLA DR7 was similar in North American patients and controls (27% vs. 19%, P=0.2), but it was lower than in Italian controls (19% vs. 29%, P=0.059). Seropositive Italian patients had a lower frequency of HLA DR11 than seronegative Italian patients and Italian controls (18% vs. 34%, P=0.07, and 18% vs. 35%, P=0.02, respectively). In contrast to seropositive Italian patients, North American patients had HLA DR4 (30% vs. 12%, P=0.02), HLA DR13 (29% vs. 10%, P=0.01), and the B8-DR3-DQ2 haplotype (23% vs. 6%, P=0.01) more often. Similarly, HLA DR4 and the B8-DR3-DQ2 phenotype were more frequent in North American patients than in Italian controls (30% vs. 16%, P=0.005, and 23% vs. 7%, P=0.00002, respectively). HLA DR7 is associated with the development of microsomal antibodies in Italian patients with chronic hepatitis C. The lower frequency of HLA DR7 in North America could contribute to the rarity of these antibodies in this region. HLA DR11 may be protective against the development of microsomal antibodies in Italian patients, whereas HLA DR4, HLA DR13, and the B8-DR3-DQ2 haplotype may be protective in North American patients.
authors.affiliation: Department of Internal Medicine, Cardioangiology, Hepatology, Policlinico Sant'Orsola-Malpighi, Bologna, Italy. paolomuratori@tin.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Muratori
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Czaja
authors.forename: Luigi
authors.initials: L
authors.lastname: Muratori
authors.forename: Alessandro
authors.initials: A
authors.lastname: Granito
authors.forename: Marcello
authors.initials: M
authors.lastname: Guidi
authors.forename: Silvia
authors.initials: S
authors.lastname: Ferri
authors.forename: Umberto
authors.initials: U
authors.lastname: Volta
authors.forename: Wilma
authors.initials: W
authors.lastname: Mantovani
authors.forename: Georgios
authors.initials: G
authors.lastname: Pappas
authors.forename: Fabio
authors.initials: F
authors.lastname: Cassani
authors.forename: Marco
authors.initials: M
authors.lastname: Lenzi
authors.forename: Francesco B
authors.initials: FB
authors.lastname: Bianchi
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000235:genetics* / Q000276:immunology; D005260:Female; D006684:HLA-DR Antigens / Q000235:genetics* / Q000276:immunology; D015809:HLA-DR7 Antigen / Q000235:genetics; D019698:Hepatitis C, Chronic / Q000235:genetics* / Q000276:immunology; D019693:Hepatitis, Autoimmune / Q000235:genetics; D006801:Humans; D007558:Italy; D008297:Male; D008862:Microsomes, Liver / Q000276:immunology; D008875:Middle Aged; D009656:North America; D044465:White People / Q000235:genetics*
chemical_list: D001323:Autoantibodies; D006684:HLA-DR Antigens; D015809:HLA-DR7 Antigen; C060729:anti-liver kidney microsome antibody