Very close linkage between HLA-B and Bf inferred from allelic association

The Bf system in diabetes-gene interaction or linkage disequilibrium?

“…It is well established that there is a strong association between B8 and DR3. Our findings are identical with those of Arnason et al [16], who also found a 100% allelic association between B8 and BfS. These observations confirm the original reported increase of BfS in Type 1 diabetes [19: NB.…”

“…Therefore it follows that in the BfF1-B 18-CW5 haplotype, there is very strong allelic association between the genes which determine these specificities, reflecting the close proximity of the relevant loci and the very low frequency of recombinations between them. Linkage disequilibrium between certain alleles at the HLA-B and Bfloci has been reported in several populations [16,17], and the occurrence of BfF1 as a component of the B I8-CW5-AW30 haplotype in Southern Europe has already been mentioned [11]. No strong HLA-A locus association with BfF1-B 18-CW5 was found in the present study.…”

Murine binding protein of the fourth component of complement: structural polymorphism and its linkage to the major histocompatibility complex.

“…IEF in low-endosmosis agarose gel followed by immunofixation (39) was performed as described (5) with slight modifications. To prepare the agarose gel, 20 ml ofagarose (0.5% IsoGel, Marine Colloid Division, Rockland, ME)/3 M urea/0.5% Nonidet P-40/3% Ampholines (pH 3.5-10) was poured onto a glass plate (100 X 130 mm). EDTA/mouse plasma was incubated at 40C for 18 hr with neuraminidase at a final concentration of 5 units/ml and then mixed with an equal volume of precooled 6 M urea/1% Nonidet P-40.…”

“…Studies from many laboratories, including ours, have demonstrated the linkages between the major histocompatibility complex and the loci controlling biosynthesis of these constituents of C3 convertase. Thus, the linkages to major histocompatibility complex of the genes controlling the following traits has been established: (i) serum C4 (Ss protein) level in mouse (2, 3); (ii) allotypic difference of C4 in mouse (4)(5)(6), guinea pig (7), and man (8)(9)(10); (iii) deficiency ofC4 in man (11) and guinea pig (12); (iv) expression of a subclass of mouse C4 (sex-limited protein) (13); (v) allotype (14,15) and deficiency (16) ofhuman C2; (vi) serum C2 level in mouse (17); (vii) allotype of factor B in man (18)(19)(20)(21), rhesus monkey (22), and guinea pig (12); and (viii) allotype of mouse C3 (23)(24)(25)(26). It should be emphasized that, of the many complement proteins, none but these constituent proteins of the amplification C3 convertase are under the genetic control of major histocompatibility complex-linked loci (27)(28)(29).…”

“…The complement system, one of the major defense mechanisms of vertebrates against microbial organisms, consists of perhaps 20 component proteins (e.g., C2, C3, C4) (1). Complement proteins can be activated by two pathways, the classical and the alternative.…”