Paternal exclusion: allele sharing in microsatellite testing.

BACKGROUND: A paternity disagreement analyzed with 15 autosomal microsatellite markers indicated allele sharing between the mother, questioned child and the alleged father generating an inconclusive paternity result. DESIGN AND METHODS: In total, 15 autosomal and 17 Y tandem repeat loci were analyzed using AmpF/STR Identifiler, AmpF/STR Y-filer kits followed by six microsatellite markers on X chromosome in DNA extracted from peripheral blood samples of the mother, questioned child and alleged father. RESULTS: Microsatellite analysis examined with 15 autosomal short tandem repeats (STRs) indicated at least one allele sharing at 14 loci between the mother, questioned child and alleged father except for the TPOX locus where a paternal-child allele mismatch was observed. Y chromosome investigations using 17 repeat markers signified the case as non-paternity (exclusion). A complete match of the six X chromosome loci in the questioned child with the mother was observed. CONCLUSIONS: Our investigations on inconclusive paternity due to atypical allele sharing in autosomal microsatellites were resolved with X- and Y-chromosome STR analyses confirming the case as non-paternity.

Single and double incompatibility at vWA and D8S1179/D21S11 loci between mother and child: implications in kinship analysis.

BACKGROUND: Two cases of paternity dispute, examined with 17 autosomal short tandem repeats signified a possible single and double maternal mismatch at vWA and D8S1179/D21S11 loci in the children under investigation. METHODS: Seventeen autosomal STR loci were analyzed using AmpFlSTR Identifiler, PowerPlex 16 kits. Six STR markers on X chromosome were amplified and analyzed. Mutated alleles were amplified, cloned in pCR(R)II-Topo vector, sequenced and investigated. RESULTS: In case S1 the vWA locus indicated an allele mismatch with the mother. All the vWA alleles on amplification, cloning and sequencing depicted an increase of 2 repeats in the child. In case D1 maternal child inconsistency at D8S1179 and D21S11 loci was observed. The alleles were amplified, cloned and sequenced to analyze the repeat structure. Increase of 1 repeat in D8S1179 locus and an insertion mutation in D21S11 locus between the mother and questioned child were confirmed. A complete match with the 17 autosomal loci of the father and 6 X chromosome STR loci of the mother was observed in both the cases. CONCLUSION: This is the first report of a maternally transmitted single mismatch at vWA locus and double mismatch at D8S1179 and D21S11 loci due to increase/mutation of the repeat in the paternity DNA testing. The results of nucleotide sequencing and STR analyses convincingly established that the suspected father and the mother are undeniably the biological parents of the questioned child.

Mother-child double incompatibility at vWA and D5S818 loci in paternity testing.

BACKGROUND: In a paternity dispute case, 17 autosomal short tandem repeats (STR) were examined and signified a possible paternal mismatch at vWA locus and a maternal mismatch at D5S818 locus in the child under investigation. METHODS: Seventeen autosomal, 17 Y-chromosome and six X-chromosome repeat loci were used in parentage analysis. The mutated vWA and D5S818 alleles were amplified, cloned and sequenced to analyze the repeat structure. RESULTS: The vWA locus genotype in the mother, questioned child and suspected father were 18/19, 16/18 and 14/18, and were 13/15, 11/12 and 11/14, respectively, for the D5S818 locus. A complete match with the mother at six X-chromosome STR loci and with the father at 17 Y-chromosome STR loci was observed. Nucleotide sequence analysis of the family at vWA alleles indicated the maternal loss of the repeat motif TCTA by two repeat units and a loss of AGAT repeat by one unit in the D5S818 locus leading to an allele mismatch in the child. The probability of maternity and paternity were 0.999999 and 0.999999, respectively. CONCLUSIONS: This is the first study of a maternally transmitted microsatellite mutation in the loci D5S818 and vWA in paternity DNA testing. The results convincingly established that the mother and suspected father are the biological parents of the questioned child.

Microsatellite mutation in the maternally/paternally transmitted D18S51 locus: two cases of allele mismatch in the child.

BACKGROUND: We investigated 2 cases of paternity dispute with 17 autosomal short tandem repeats (STR), that indicated a mismatch to the maternally and paternally inherited allele at D18S51 locus in children under inquiry. METHODS: 17 autosomal and Y STR loci were analyzed using AmpFlSTR Identifiler, PowerPlex 16, AmpFlSTR(R)Y-filertrade mark kits. The mitochondrial DNA hypervariable regions HV1 and HV2 and 6 STR markers on X chromosome were amplified and sequenced. RESULTS: In case M1, allelic representation in the mother, questioned child and suspected father was 14/19, 12/20 and 12/14 respectively. A complete match with the mother at 6 X STR loci and mitochondrial hypervariable regions was observed. In case F1, allelic representation was 13/14, 14/20 and 16/18 respectively. A complete match with the father at 17 Y chromosome STR loci was observed. D18S51 sequence analysis indicates the expansion of 1 repeat in M1 and 2 repeats in F1 leading to allele mismatch in the child. CONCLUSION: The probability of maternity and paternity were 0.999999 and 0.999999 respectively. This is the first report of a maternally/paternally transmitted D18S51 mutations in the paternity DNA testing. These results conclusively determined that the mother and suspected father are the biological parents of the questioned children in both the cases.