Confirmation of Paternity despite Three Genetic Incompatibilities at Chromosome 2

Abstract

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.

Analysis of homozygous allele mismatches in paternity tests with massively parallel sequencing

“…The other allele of the child differs from the allele of the father in that the child has lost the last repeat motif [TCTA] (Figure 2). No mismatches were detected in the SNP genotypes on chromosome 3 between the child and the father, indicating that no chromosomal aberrations occurred [16]. Therefore, these mismatches could be attributed to the mutation resulting from a replication error during the genetic process.…”

Maternal Uniparental Isodisomy of Chromosome 2 Leading to Homozygous Variants in SPR and ZNF142: A Case Report and Review of the UPD2 Literature

“…Two of these cases had complete maternal UPD2; four had complete paternal UPD2; one had complete maternal isodisomy resulting from two maternal isochromosomes i(2q) and i(2p). 23 24 25 26 27 28 29 Parental origin was not reported in one case. 30 …”

“…Two of these cases had complete maternal UPD2; four had complete paternal UPD2; one had complete maternal isodisomy resulting from two maternal isochromosomes i(2q) and i(2p). [23][24][25][26][27][28][29] Parental origin was not reported in one case. 30 The ages at which individuals with UPD2 and a normal phenotype was reported ranged from 18 months to 36 years.…”