Mutations or exclusion: an unusual case in paternity testing.

In an immigration case with the scope of family reunification, the DNA extracted from the saliva samples of the male child, the alleged mother and the putative father was typed with 22 autosomal short tandem repeat (STR) systems. In seven STR systems, the alleged mother could be excluded from maternity, and the case then had to be regarded as a deficiency case. Taking this fact into consideration, only two exclusions were found for the putative father, and the question arose whether there was an exclusion of the putative father or the existence of two mutations. Autosomal STR typing could not clarify the case, but the application of eight Y-chromosomal markers showed that the alleged father could be excluded from paternity.