Figure. Genetic basis for the Neisseria meningitidis strain that cannot be placed in a known serogroup. A predicted slipped-strand mispairing occurred within synD, which encodes the serogroup B sialyltransferase. In wild-type N. meningitidis serogroup B (MC58), the synD polyC tract contains 7 C residues, and capsule is expressed. When an insertion (as in isolate 100924) of 1 C residue occurs, a result of local denaturation and mispairing followed by replication or repair, a premature stop codon is generated, and the capsule is not expressed.