IgW VH form multiple families. The deduced amino acid sequences of the IgW cDNA clones (Genbank accession #AY609225-AY609246, AY531553-AY531554, AY524297) were compared to the predicted amino acid sequence of conventional IgW U51450  and aligned in ClustalW with differences in FR and CDR separating the clones into six groups. Dashes (-) indicate identity with the first sequence and gaps introduced to correct alignment are indicated by slashes (/). The CDR3 are unique for most clones demonstrating the neonatal repertoire is diverse in the IgW isotype. The Cys (*) typically important for light chain association is mutated in several members of groups I and II.