ABSTRACT. Male infertility is considered to be a difficult-to-treat condition because it is not a single entity, but rather reflects a variety of different pathologic conditions, thus making it difficult to use a single treatment strategy. Structural alterations in the Y chromosome have been the principal factor responsible for male infertility. We examined 26 family members of 13 patients with male infertility who showed deletions in the AZF region. In family 1, the father and a brother did not show microdeletions. However, a son showed a microdeletion in AZFa (sY84) and an azoospermic sperm analysis, but another son had a microdeletion in AZFa (sY84) and AZFb (sY127) and a normal sperm analysis. The father of family 2, with severe oligozoospermia, had a microdeletion in the AZFa region (sY84) and his son, conceived by intracytoplasmic sperm injection, also showed the same microdeletion. In the other families, only the men with an altered sperm analysis had a microdeletion. It is possible that in family 1, the father and brother who did not show microdeletions in this study, could have microdeletions in regions upstream or downstream of the one analyzed. The treatment with intracytoplasmic sperm injection can result in vertical transmission of microdeletions of the AZF region and can also cause the expansion of a de novo mutation. This finding reinforces the necessity of an
The appearance of new mutations in polymorphic markers plays a central role in a range of genetic applications, including dating phylogenetic events, informing disease studies, and evaluating forensic evidence. The present study estimated the mutation rates of 21 autosomal STR loci in a population from Central Brazil. We studied 15 046 paternity cases from Goiás, Brazil from August 2012 to February 2015. We identified 262 mutations in the 21 loci. The loci that presented more mutations were FGA and D18S51, with a total of 46 and 28 mutations, respectively. The results showed mutational rates ranging from 1.7 × 10 to 7.6 × 10 mutations per site/region and the overall mutational rate was 2.1 × 10 ; these values were within the expected values for the STR markers. The most common type of mutation was one-step mutation, which totaled 96.2%. We found a higher rate of mutations of paternal origin (67.6%) than of mutations of maternal origin. The occurrence of mutations in STRs has important consequences for human identification, including the definition of criteria for exclusion in paternity testing and interpretation of genetic profiles in criminal cases.
A serious radiological accident occurred in 1987 in Goiânia, Brazil, which lead to extensive human and environmental contamination as a result of ionising radiation (IR) from caesium-137. Among the exposed were those in direct contact with caesium-137, their relatives, neighbours, liquidators and health personnel involved in the handling of the radioactive material and the clean-up of the radioactive sites. The exposed group consisted of 10 two-generation families, totalling 34 people. For each exposed family, at least one of the progenitors was directly exposed to very low doses of γ-IR. The control group consisted of 215 non-irradiated families, composed of a father, mother and child, all of them from Goiânia, Brazil. Genomic DNA was purified using 100 μl of whole blood. The amplification reactions were prepared according to PowerPlex® 16, following the manufacturer's instructions. Genetic profiles were obtained from a single polymerase chain reaction amplification. The exposed group had only one germline mutation of a paternal origin in the 'locus' D8S1179 and the observed mutation presented a gain of only one repeat unit. In the control group, 11 mutations were observed and the mutational events were distributed in five loci D16S539, D3S1358, FGA, Penta E and D21S11. The mutation rates for the exposed and control groups were 0.006 and 0.002, respectively. There was no statistically significant difference (P = 0.09) between the mutation rate of the exposed and control groups. In conclusion, the quantification of mutational events in short tandem repeats can provide a useful system for detecting induced mutations in a relatively small population.
ABSTRACT. The central region of Brazil was colonized by internal migration of individuals of different origins, who contributed to the genetic diversity existing in this population. This study determined the allele frequencies and haplotype diversity of Y-STRs in Goiás State, Central Brazil, and compared the data obtained with a sample of the Brazilian population, consisting of individuals from the five geographical regions of Brazil. A total of 353 males were typed for Y-STR haplotype diversity in Central Brazil 12 Y-chromosome short tandem repeat (Y-STR) markers. We selected males who had no degree of relatedness, from the five mesoregions of Goiás State. DNA was extracted from blood samples followed by the amplification of the 12 Y-chromosome loci. The products were analyzed to obtain the allele profiles on an ABI3500 automated sequencer using the Gene Mapper software. Allele frequencies and haplotype diversity were estimated by direct counting, and gene diversity for each locus was computed using the Arlequin software. The results are consistent with the history of miscegenation of the population of Central Brazil, in which we observed 321 different haplotypes. The average gene diversity at the 12 loci was 0.645. DYS385b and DYS389I showed the highest (0.704) and lowest (0.520) genetic diversity values, respectively. The F ST value between the Brazilian and Goiás populations was 0.00951, showing no statistical significance. The results of this study allowed the establishment of haplotypes found in the forensic samples of Goiás State serving as a reference in the elucidation of criminal cases and paternity tests, as well as population and evolutionary inferences.
ABSTRACT. In studies of human identification, obtaining a high standard of outcomes and satisfactory conclusions are directly related to the use of highly polymorphic molecular markers. In addition to the combined DNA index system (CODIS) group, it is also important to implement non-CODIS markers into the analysis, as they increase the power of discrimination. During the identification process, it is essential to consider the genetic variation among distinct groups of populations, as the allele frequencies 7311 CODIS and non-CODIS STR allele frequencies in Brazil ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (3): 7310-7314 (2015) are directly associated with the power of discrimination. However, the population of Goiás, a State located in Central Brazil, is characterized by a highly mixed population due to its diverse ethnic origins. In this study, a survey of the allelic frequencies in the Goiás population was carried out using a molecular assembly composed of 21 autosomal loci both from and external to the CODIS group. The new data, for some of the markers used, were statistically similar to those from previous studies. This consistency means that the use of these markers might serve as a parameter for future population comparisons. The results from these analyses further our knowledge of the study of human identification.
ABSTRACT. This study aimed to develop a short tandem repeat (STR) multiplex system, made up of 22 highly informative STR loci, for application in forensic genetics. The system comprised 21 polymorphic autosomal loci (D3S1358, TH01, D21S11, D18S51, Penta E, D5S818, 2 R.G. Rodovalho et al.Genetics and Molecular Research 16 (2): gmr16029557 D13S317, D7S820, D16S539, CSF1PO, Penta D, vWA, D8S1179, TPOX, FGA, D2S441, D17S1301, D19S433, D18S853, D20S482, and D14S1434) and the amelogenin gene locus. Strategies were developed to overcome the challenges involved in creating a multiplex system. Based on the literature and available databases, the STR loci were selected with the aim to obtain discriminatory markers, and followed specific criteria for this purpose. Primers were projected using the Primer3 software, and AutoDimer was used to evaluate possible interactions between them. The 22 selected STR loci were validated individually and jointly, both to assess their sensitivity and to test the efficiency of the multiplex system. Statistical analyses were based on the genetic data of 450 unrelated individuals living in the State of Goiás, thus allowing the establishment of the parameters necessary to use this system. A total of 239 alleles were detected for the 22 loci in the set, allowing for a probability of identity of 4.23 x 10 -25 to be obtained. The combined power of discrimination was 0.999999999999999999999999 and the combined power of exclusion was 0.99999. Upon complete validation of the entire system, this multiplex assay was considered to be a powerful tool for application in human identification by DNA analysis.
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