Problems arising from the use of the HLA system in paternity testing

Characterization of the HLA antigens present on lymphocytes has become an important procedure in paternity testing. This paper presents data on two cases in which the HLA antigens exhibited by the mother, child and alleged father were consistent with paternity but where the other genetic markers clearly showed exclusion of paternity. The use of HLA data alone to calculate probability of paternity in these two cases produced misleading figures. Caution must be exercised in using HLA results to calculate the probability of paternity, especially when there is reason to believe that the alleged and natural fathers are relatives.