rG. Potential pitfall in parentage testing.

Extensive studies were done on the family of an infant investigated for possible hemolytic disease of the newborn (HDN). Fourteen members in four generations were shown to carry the rG gene with r, R1 or R2. If testing had not included anti-CD(G) serum, three false exclusions of paternity and four of maternity might have resulted in this large Caucasian family. The findings also demonstrated that titration of Rh antisera against the red cells of family members could not be relied upon to assess zygosity or dosage.