Genetic polymorphisms in semen stains of azooespermic individuals: medical-legal implications

• Grant number: 18/03587-6
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2019
• End date: August 31, 2021
• Field of knowledge: Health Sciences - Medicine
• Principal Investigator: Edna Sadayo Miazato Iwamura
• Grantee: Edna Sadayo Miazato Iwamura
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated researchers: Eloisa Aurora Auler Bittencourt

Abstract

The analysis of microsatellite markers of the Y chromosome (Y-STR) has been widely used in forensic identification, kinship testing and population studies. In cases of rape, or pregnancy resulting from rape where suspects have a degree of kinship, determination of the Y-STR haplotype becomes fundamental. In the international literature, parent / child pairs previously confirmed by autosomal STRs (As-STR) were tested using Y-STR in different populations (including Brazilian), and describe the existence of mutations among the paternal Y-STR alleles and the son´s. To date, we have not found comparative studies in the literature demonstrating the existence of Y-STR allele mutations between haploid and diploid cells of the same individual. In clinical diagnoses of genetic diseases, analyzing these STR-Y mutations is relevant when it comes to changes that may confuse and impair the likelihood ratio (LR) determination between genetic profiles. In cases of sexual crime where there is no potential suspect, it is possible to determine the genetic profile of the material collected from the victim and store it in a Genetic Profile Database for later comparisons with profiles of any suspected individuals. A more accurate understanding of the haplotypes and the most frequent mutations will benefit these applications. Objective of the project: to compare genetic profiles of DNA obtained after amplification of 27 As-STR loci and 23 Y- STR loci extracted from cells of different origins of the same individual. Material and Methods: 360 biological samples collected from 90 male volunteers in the pre-vasectomy phase will be analyzed: (a) 90 samples of DNA extracted from semen in natura; (b) 90 samples of DNA extracted from blood in natura; (c) 90 samples of semen spot deposited on cotton cloth; and in the post-vasectomy phase (d) 90 samples of seminal fluid spot of the genito-urinary tract. Cotton fabric stains are stored for a period of 14 years. The DNA extracted from these samples will be amplified by PCR and evaluated 27 STR loci, 23 autosomal, 3 Y chromosome and Amelogenin (PowerPlex Fusion6C System) and 23 Y chromosome loci (STR-Y), using the Power Plex Y23. We will use the ABI 3500XL (AppliedBiosystem) sequencer. Analyzes of the results of the genetic profiles will be performed by Gene Mapper ID-X software. When there are inconsistencies or presence of mutations will be performed sequencing of Sanger according to procedures of our laboratory.The most frequently mutated types and mutations will be evaluated. (AU)