title: Identical point mutation leading to low levels of mannose binding protein and poor C3b mediated opsonisation in Chinese and Caucasian populations.
abstract: A common opsonic defect occurring in 7% of the Caucasian population is associated with low serum levels of the lectin mannose binding protein (MBP). This study sought to determine whether the deficiency was also present in a Chinese population using sera obtained from 100 healthy Chinese children (age range 6 weeks-16 years). The distribution profiles of MBP levels and C3b/C3bi fragments binding to mannan coated plates were both bimodal and similar to the corresponding Caucasian profiles. Serum MBP levels were low in 9% of the Chinese children and all of these sera generated low levels of C3b/C3bi fragments. Overall there was a high significant correlation between MBP levels and C3b opsonin generation (r = 0.77; P less than 0.001). By analogy with similar findings in a Caucasian population we believe this correlation to be a reflection of antibody independent complement activation by MBP. In a pilot study of DNA obtained from three adult Chinese with low MBP levels the point mutation causing MBP deficiency in Caucasians was identified in all three cases.
authors.affiliation: Institute of Child Health, University of London, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Lipscombe
authors.forename: Y L
authors.initials: YL
authors.lastname: Lau
authors.forename: R J
authors.initials: RJ
authors.lastname: Levinsky
authors.forename: M
authors.initials: M
authors.lastname: Sumiya
authors.forename: J A
authors.initials: JA
authors.lastname: Summerfield
authors.forename: M W
authors.initials: MW
authors.lastname: Turner
mesh_terms: D000293:Adolescent; D044466:Asian People / Q000235:genetics; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D003179:Complement C3b / Q000032:analysis; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D037241:Mannose-Binding Lectins; D016297:Mutagenesis, Site-Directed; D009895:Opsonin Proteins / Q000097:blood; D044465:White People / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D037241:Mannose-Binding Lectins; D009895:Opsonin Proteins; D003179:Complement C3b