Supervisors info:
Λιανίδου Εύη, Καθηγήτρια Αναλυτικής Χημείας - Κλινικής Χημείας, Τμήμα Χημείας, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών.
Ψαρρά Κατερίνα, Χημικός MSc - PhD, Τμήμα Ανοσολογίας - Ιστοσυμβατότητας ΓΝΑ "Ο Ευαγγελισμός".
Summary:
Introduction: Autosomal Short Tandem Repeats (aSTRs) widely used in disputed paternity/maternity assessment. The aim of this study was to evaluate the impact of aSTRs mutations in parentage cases.
Materials/Methods: In the period from 2014 to 2019 a total of 690 DNA samples (261 parentage testing cases, 34 of which were fatherless or motherless cases) were investigated. G-DNA was isolated from whole blood and/or buccal swabs. Analysis was performed using 16 aSTRs loci (D10S1248, vWA, D16S539, D2S1338, D8S1179, D21S11, D18S51, D22S1045, D19S433, TH01, FGA, D2S441, D3S1358, D1S1656, D12S391, SE33), using DNA AmpFlSTR® NGM SElect™ commercial Kit and analysis of PCR products by electrophoresis on 3130 Genetic Analyzer. Fragment sizes were determined automatically using the GeneMapper® ID Software IDX1.3. Power of Exclusion (PE), Random Man Not Excluded (RMNE), Combined Parentage Index (CPI), and Probability of Parentage (W) values were calculated using allele frequency of Caucasoid.
Results: Out of 261 cases, 49 were excluded by aSTRs (at least 3 genetic aSTRs loci) and 212 were not excluded. Fourteen aSTR mutations (3 from each SE33, vWA and D12S391, and 1 from each FGA, D8S1179, D10S1248, D3S1358, D2S1338 locus) and 1 null allele (SE33) were observed in 15 (15/212, 7,07%) different parent/child allele transfers (1 of them was motherless case), without ruling out fatherhood. Mutations were single or double-step (repeat loss or gain). The ratio of paternal versus maternal mutations/null allele was statistically significant (14:1, p=0.001).
Conclusions: Paternity testing using aSTRs is an accurate and high-sensitivity method with the possibility of resolving kinship cases up to 2nd degree. It is recommended that a) both parents be controlled in all cases to avoid the risk of wrong inclusion due to the absence of mother or father’s genotype, b) the use of additional genetic aSTRs loci in case of mutations in order to minimize the possibility of false exclusion.
Keywords:
STRs mutations, paternity test, maternity test, disputed parenthood
