Absence of the mother
In the majority of cases, three subjects undergo paternity testing: the mother, the child and the presumed father. In some situations, given the enormous potentiality of the analytic system used, the test can furnish accurate and reliable results with participation of the father and child and not the mother. The results are technically more difficult to obtain but are the same as those carried out on three subjects. The lack of genetic information derived from the mother is made up for by the investigation of a greater number of DNA regions than those utilized when the mother's DNA is available.

Absence of the father
In other situations, it is possible that the presumed father has died, or is in any case unavailable. In this case the operative strategic possibilities will be evaluated case-by-case, with the utilization of biological material available. In certain cases, in fact, it is possible to have the parent of the absent person undergo the test: these are complex cases whose feasibility must be evaluated with extreme caution. In other cases, with certain limitations, close relatives to the absent party can undergo genetic testing; in still others, biological material from when the defunct person was alive can be used. The exhumation of the remains sometimes represents the only solution to the question of paternity.