tokens: Type I C2 deficiency was described in a family in which the C2 null allele ( C2Q0 ) is associated with the major histocompatibility haplotype / complotype HLA - A25 , B18 , C2Q0 , BfS , C4A4 , C4B2 , Drw2 ; this extended haplotype occurs in over 90 % of C2 - deficient individuals ( common complotype / haplotype ) .