DNA testing in cases of disputed paternity is a routine analysis carried out in genetic laboratories. The purpose of the test is to demonstrate similarities and differences in analyzed genetic markers between the alleged father, mother, and a child. The existence of differences in the examined loci between the child and the presumed father may indicate the exclusion of biological parenthood. However, another reason for such differences is genetic mutations, including chromosome aberrations and genome mutations. The presented results relate to genetic analyses carried out on three persons for the purposes of disputed paternity testing. A deviation from inheritance based on Mendel's Law was found in 7 out of 53 STR-type loci examined. All polymorphic loci that ruled out the paternity of the alleged father were located on chromosome 2. Additional analysis of 32 insertion-deletion markers (DIPplex, Qiagen) and sequencing of 94 polymorphic positions of the single nucleotide polymorphism (SNP) type (Illumina, ForenSeq) did not exclude the defendant's biological paternity. A sequence analysis of STR alleles and their flanking regions confirmed the hypothesis that the alleles on chromosome 2 of the child may originate only from the mother. The results of the tests did not allow exclusion of the paternity of the alleged father, but are an example of uniparental maternal disomy, which is briefly described in the literature.
Keywords: paternity testing; short tandem repeat profiling; trisomy rescue; uniparental disomy.