Polimorfismos de inserção/deleção no cromossomo X : análise de 32 marcadores na população da região sudeste do Brasil
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Data
2020-05-26
Autores
Silva, Flávia Alves de Jesus
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Universidade Estadual Paulista (Unesp)
Resumo
Na rotina forense, há casos em que a amostra biológica se encontra degradada ou com baixa concentração de DNA, o uso exclusivo dos marcadores STRs pode gerar um resultado estatístico inconclusivo, tornando fundamental a análise de marcadores adicionais para a resolução do caso. Utilizado como método complementar, os polimorfismos de inserção e deleção (InDels) têm mostrado grande potencial para superar as limitações dos marcadores tradicionais. Adicionalmente, estudos de genética forense tem sido cada vez mais explorados no âmbito do cromossomo X, especialmente nos casos em que a análise dos autossômicos não é suficiente. Nessa perspectiva, este trabalho avaliou a utilidade de um conjunto de 32 polimorfismos de inserção/deleção do cromossomo X em amostras da população da região sudeste do Brasil. Afim de avaliar a diversidade genética destas populações, foram analisados os perfis genotípicos de 627 indivíduos sem relação genética pelo cromossomo X, residentes nos estados de Minas Gerais (90 mulheres e 116 homens), Espírito Santo (201 homens) e Rio de Janeiro (220 homens). Os resultados indicam que o painel dos 32 X-InDels é bastante eficiente para a sua finalidade, sendo que praticamente todos os marcadores se mostraram altamente informativos para as populações estudadas. O teste de equilíbrio de Hardy-Weinberg foi realizado nas amostras femininas de Minas Gerais e não foram verificados desvios significativos. Em todas populações analisadas o painel demonstrou alta eficiência forense, confirmado pelo alto poder de discriminação para Minas Gerais (PDF=0,999999999994 e PDM=0,99999994), Espírito Santo (PDF=0,999999999994 e PDM=0,99999995) e Rio de Janeiro (PDF=0,999999999997 e PDM=0,99999997), e pelo elevado poder de exclusão estimado em trios: pai/mãe/filha (Minas Gerais: 0,999996; Espírito Santo: 0,999996; Rio de Janeiro: 0,999997) e duos: pai/filha (Minas Gerais: 0,9994; Espírito Santo: 0,9995; Rio de Janeiro: 0,9996). No estudo comparativo com outras populações, a maior similaridade observada foi das 3 populações estudadas neste trabalho com as outras populações brasileiras, seguido pelas populações dos departamentos colombianos e Europa. Durante a análise foi observada, nas três populações estudadas, a presença de uma variante no MID1361. Na análise de ancestralidade para estas populações, foi identificada proporções ancestrais de europeus (MG= 39%, RJ= 35% e ES= 38%), africanos (MG= 36%, RJ= 38% e ES= 37%) e nativo-americanos (MG= 25%, RJ= 27% e ES= 25%). Os dados para os marcadores de inserção/deleção no cromossomo X disponíveis na literatura vêm sendo cada vez mais explorados, mas o conhecimento sobre este assunto deve ser ampliado. Os valores de poder de discriminação e exclusão obtidos neste trabalho já demonstram seu potencial como método complementar para a análise de amostras forenses.
In the forensic routine, there are cases in which the biological sample is degraded or with a low concentration of DNA, the exclusive use of STR markers can generate an inconclusive statistical result, making the analysis of additional markers essential for the resolution of the case. Used as a complementary method, the insertion and deletion polymorphisms (InDels) have shown great potential to overcome the limitations of traditional markers. Additionally, the X chromosome has been increasing significant importance in forensic genetics studies, especially in cases where the analysis of autosomal is not enough. In this perspective, this work evaluated the usefulness of a set of 32 polymorphisms of insertion/deletion of the X chromosome in samples from the population of the southeastern region of Brazil. In order to evaluate the genetic diversity of these populations, the genotypic profiles of 627 individuals without genetic relationship were analyzed by the X chromosome, living in the states of Minas Gerais (90 females and 116 males), Espírito Santo (201 males) and Rio de Janeiro (220 males). The results indicate that the 32 X-InDels panel is enough efficient for its purpose, with practically all the markers proving to be highly informative for the studied populations. The Hardy-Weinberg equilibrium test was performed on female samples from Minas Gerais and no significant deviations were found. In all analyzed populations, the panel demonstrated high forensic efficiency, confirmed by the high power of discrimination for Minas Gerais (PDF= 0.9999999999994 and PDM= 0.999999994), Espírito Santo (PDF=0.999999999994 and PDM= 0.99999995) and Rio de Janeiro (PDF= 0.999999999997 and PDM= 0.99999997), and the high exclusion power estimated in trios: father/mother/daughter (Minas Gerais: 0.999996; Espírito Santo: 0.999996; Rio de Janeiro: 0.999997) and duo: father/daughter (Minas Gerais: 0.9994; Espírito Santo: 0.9995; Rio de Janeiro: 0.9996). In the comparative study with other populations, the greatest similarity observed was between the 3 populations studied in this work, followed by the other Brazilian populations, from the Colombian departments and Europe. During the analysis, the presence of a variation in MID1361 was observed in the three populations studied. In the analysis of ancestry for these populations, ancestral proportions of Europeans were identified (MG = 39%, RJ = 35% and ES = 38%), Africans (MG = 36%, RJ = 38% and ES = 37%) and native-americans (MG = 25%, RJ = 27% and ES = 25%). The data for insertion / exclusion markers on the X chromosome are available in the has been increasingly explored literature, but the knowledge on this subject must be expanded. The values of discriminating power and excluding them in this work already demonstrate its potential as a complementary method for analyzing forensics.
In the forensic routine, there are cases in which the biological sample is degraded or with a low concentration of DNA, the exclusive use of STR markers can generate an inconclusive statistical result, making the analysis of additional markers essential for the resolution of the case. Used as a complementary method, the insertion and deletion polymorphisms (InDels) have shown great potential to overcome the limitations of traditional markers. Additionally, the X chromosome has been increasing significant importance in forensic genetics studies, especially in cases where the analysis of autosomal is not enough. In this perspective, this work evaluated the usefulness of a set of 32 polymorphisms of insertion/deletion of the X chromosome in samples from the population of the southeastern region of Brazil. In order to evaluate the genetic diversity of these populations, the genotypic profiles of 627 individuals without genetic relationship were analyzed by the X chromosome, living in the states of Minas Gerais (90 females and 116 males), Espírito Santo (201 males) and Rio de Janeiro (220 males). The results indicate that the 32 X-InDels panel is enough efficient for its purpose, with practically all the markers proving to be highly informative for the studied populations. The Hardy-Weinberg equilibrium test was performed on female samples from Minas Gerais and no significant deviations were found. In all analyzed populations, the panel demonstrated high forensic efficiency, confirmed by the high power of discrimination for Minas Gerais (PDF= 0.9999999999994 and PDM= 0.999999994), Espírito Santo (PDF=0.999999999994 and PDM= 0.99999995) and Rio de Janeiro (PDF= 0.999999999997 and PDM= 0.99999997), and the high exclusion power estimated in trios: father/mother/daughter (Minas Gerais: 0.999996; Espírito Santo: 0.999996; Rio de Janeiro: 0.999997) and duo: father/daughter (Minas Gerais: 0.9994; Espírito Santo: 0.9995; Rio de Janeiro: 0.9996). In the comparative study with other populations, the greatest similarity observed was between the 3 populations studied in this work, followed by the other Brazilian populations, from the Colombian departments and Europe. During the analysis, the presence of a variation in MID1361 was observed in the three populations studied. In the analysis of ancestry for these populations, ancestral proportions of Europeans were identified (MG = 39%, RJ = 35% and ES = 38%), Africans (MG = 36%, RJ = 38% and ES = 37%) and native-americans (MG = 25%, RJ = 27% and ES = 25%). The data for insertion / exclusion markers on the X chromosome are available in the has been increasingly explored literature, but the knowledge on this subject must be expanded. The values of discriminating power and excluding them in this work already demonstrate its potential as a complementary method for analyzing forensics.
Descrição
Palavras-chave
Análise de DNA, Polimorfismo (Genética), Cromossomo X, Marcadores genéticos, Identificação humana, Genética populacional, InDels, Polimorfismo de inserção/deleção, X-InDels, Minas Gerais, Espírito Santo, Rio de Janeiro, Brasil, Human identification, Population genetics, Insertion/deletion polymorphism, InDels, X chromosome, Brazil