Linkage group HL-A-MLC-Bf (properdin factor B)

Abstract

Genetic linkage between the HL-A and Bf loci could be confirmed in 43 families with 168 offspring. In 4 families, 5 recombinants out of 82 informative meiotic divisions were observed (r = 6.1%). The localisation of the Bf marker system was studied in 3 families with crossovers between HL-A and MLC. From these data the following map order of human chromosome 6 can be proposed: HL-A (1st locus) -- HL-A (2nd locus)--MLC-Bf---PGM(3). The fact that important components of the classical and alternate pathway of complement activation are governed by genes closely linked with HL-A and MLC loci leads to the proposition to include the Bf system into the Major Histocompatibility Complex in man.

Immunochemical characterization of murine H-2 controlled Ss (serum substance) protein through identification of its human homologue as the fourth component of complement.

“…In addition to the MHCcomplement associations noted above, a locus controlling C'2 deficiency has been found to be closely linked to HL-A (14). The polymorphism of GBG (glycine-rich beta-glycoprotein), whose major cleavage product is properd1in factor B of the alternate pathway for complement activation (16), reflects structural alleles for a GBG subunit controlled by a locus (Bf) only six recombination units from HL-A (17). It is noteworthy that both properdin factor B and the C4-C2 complex are endowed with enzymatic activity for the same substrate, the C'3 component, and both mediate cleavage of that component to form factor C'3b and C3 anaphylatoxin (16).…”

Properdin Factor B (Bf) Polymorphism in Saudi Arabs

“…In particu lar, the frequency of the allotype BfF is higher than that found in most European populations where its range is between 0.112 in the Lapps [Teisberg and Olaisen, 1977] and 0.250 in Swiss Italians [Scherzet al, 1977], The BfF allotype was reported to have a high frequency in Black popula tions, with the highest frequency reported in South African Blacks ( B f = 0.655) [M auffet al, 1976] and in Efiks ( B f = 0.639) [Klouda et al, 1983]. The frequency of the most common Bf allotype B/5 in the Saudi Arabs is lower than that reported in various European populations, where it ranges from 0.718 in Italians [Sc/ierzet al, 1977] to 0.826 in Germans [Rittner et al. 1975].…”

Properdin Factor B Polymorphism in Afghanistan

“…Genetic linkage between the Bf locus and the HLA system was reported by Allen [1974] and confirmed by Olaisen et al [1975] and Rittner et al [1975].…”