Abstract
Segregation data on LW in families of informative males show that the LW (Landsteiner-Wiener) blood group locus is closely linked to the complement C3 locus and to the locus for the Lutheran blood group. This finding also confirms the presence of a larger linkage group on chromosome 19, including now the loci for apoE, Le, C3, LW, Lu, Se, H, PEPD, myotonic dystrophy (DM), neurofibromatosis (NF) and familial hypercholesterolemia (FHC). Linkage of LW with the Lewis blood group locus could not be definitely established by the present family data, but small positive scores between LW and Le suggest that the Le locus is situated outside the C3-LW region.