Search

Genomic disorders are genetic diseases that are caused by rearrangements of chromosomal material via deletions, duplications, and inversions of unique genomic segments at specific regions. Such rearrangements could result from recurrent non-allelic homologous recombination between low copy repeats. In cases where the breakpoints flank the low copy repeats, deletion of chromosomal segments is often followed by reciprocal duplication. Variations in genomic copy number manifest differently, with duplication and deletions of the same genomic region showing opposite phenotypes. Sotos syndrome is caused by alterations in the dosage of NSD1 on human chromosome 5 by either deletions or mutations, such as microdeletion of 5q35.2q35.3. In general, patients carrying reciprocal microduplication at 5q35.2q35.3 present no clinical phenotype or milder phenotype than do patients with microdeletion at the same locus. We report the first case of 5q35.2q35.3 microduplication encompassing NSD1 in a patient from central Brazil. We identified a genomic imbalance corresponding to a de novo 0.45 Mb microduplication at 5q35.2q35.3 by chromosomal microarray analysis and study of low-copy repeats. The proband had microduplication in the chromosomal region containing NSD1, which resulted in a Sotos syndrome reversed phenotype, and this duplication was associated with microcephaly, short stature, and developmental delay. Analysis of the genomic structure of the rearranged 5q35.2q35.3 chromosomal region revealed two major low-copy repeat families, which caused the recurrent rearrangements. Chromosomal microarray analysis is a potential tool to identify microrearrangements and guide medical diagnosis, which has to be followed by a non-directive genetic counseling approach to improve the quality of life of the patient.

Dioscorea is the largest genus in the Dioscoreaceae family, and includes a number of economically important species including the air yam, D. bulbifera L. This study aimed to develop new single sequence repeat primers and characterize the genetic diversity of local varieties that originated in several municipalities of Brazil. We developed an enriched genomic library for D. bulbifera resulting in seven primers, six of which were polymorphic, and added four polymorphic loci developed for other Dioscorea species. This resulted in 10 polymorphic primers to evaluate 42 air yam accessions. Thirty-three alleles (bands) were found, with an average of 3.3 alleles per locus. The discrimination power ranged from 0.113 to 0.834, with an average of 0.595. Both principal coordinate and cluster analyses (using the Jaccard Index) failed to clearly separate the accessions according to their origins. However, the 13 accessions from Conceição dos Ouros, Minas Gerais State were clustered above zero on the principal coordinate 2 axis, and were also clustered into one subgroup in the cluster analysis. Accessions from Ubatuba, São Paulo State were clustered below zero on the same principal coordinate 2 axis, except for one accession, although they were scattered in several subgroups in the cluster analysis. Therefore, we found little spatial structure in the accessions, although those from Conceição dos Ouros and Ubatuba exhibited some spatial structure, and that there is a considerable level of genetic diversity in D. bulbifera maintained by traditional farmers in Brazil.

We describe the first postnatal diagnosis of a child from Central Brazil with de novo cytogenetic alterations in 13q showing malformations of the brain, eyes, distal limbs, and genitourinary tract, and severe intellectual disability. The karyotype was a constitutive 46,XX,r(13)[77]/45,XX,-13[17]/46,XX,idic r(13)[6]. Interphase and metaphase fluorescence in situ hybridization analyses also showed the absence of 13qter and the presence of 13q14.3 in the cells with r(13), and chromosome microarray analysis detected a 15.39 Mb deletion in chromosome region 13q32.3-q34. This study is intended as the registry of a rare case of chromosomal rearrangement involving chromosome 13 in Central Brazil. Further studies are needed to define whether genetic haploinsufficiency is associated with each major 13q deletion anomaly.

Successful DNA extraction is indispensable for molecular methods based on polymerase chain reaction (PCR); however, goat sperm DNA extraction is limited. Thus, the aim of this study was to evaluate three methods to extract DNA from goat sperm for use in PCR. Eight goat semen pools were used for DNA extraction by using the DNeasy Blood & Tissue Kit, phenol-chloroform, and Chelex-100 methods. DNA samples were analyzed spectrophotometrically to determine the DNA concentration and purity, visualized on 0.8% agarose gel, and used at different amounts (150, 100, 50, 10, and 1 ng) for PCR with electrophoresis, followed by 1.5% agarose gel electrophoresis. The quantity of DNA extracted with Chelex-100 was higher (P < 0.05) than that obtained with either the DNeasy Blood & Tissue Kit or the phenol-chloroform method, with the phenol-chloroform method yielding a greater quantity (P < 0.05) than the kit. The DNeasy Blood & Tissue Kit produced a higher (P < 0.05) purity product than the Chelex-100 method, and all samples obtained by the three protocols were positive for DNA, as assessed by electrophoresis. All of the different concentrations of DNA produced by these methods were amplified by PCR, although for DNA produced by the phenol-chloroform method, PCR was only possible after complementary purification. In conclusion, the Chelex-100 method is cheap, secure, simple, fast, and effective, and is a potential tool for extracting goat sperm DNA without limitations in PCR.

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 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 FST 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.

The carmine cochineal Dactylopius opuntiae is a key pest in productive fields of forage cactus in Pernambuco, Brazil. Species identification by means of molecular markers assists in understanding the genetic profile, underpins morphological characterization, and supports the monitoring of populations in integrated management programs designed to control this pest. We evaluated the genetic variability of natural populations of D. opuntiae. Genetic variability was analyzed with ISSR and RAPD primers in 24 populations from 12 municipalities of Pernambuco State in Brazil. Morphological characterization confirmed that D. opuntiae was the only cochineal species present in all samples. Nine ISSR primers and six RAPD produced a total of 62 and 58 polymorphic fragments, respectively. Both types of markers showed an average genetic similarity of 80% regardless of the geographic origin of samples. The low genetic variability demonstrates a high degree of relatedness among these D. opuntiae populations.

We evaluated the effects of the Shahid-Rajaei dam, 14 years after its construction, on morphometric and genetic divergence between up- and downstream populations of the Iranian fish Siah-Mahi (Capoeta capoeta gracilis). Sixty-six specimens were analyzed. There were significant differences between the 2 groups in the means of 16 morphometric characters (univariate analysis). In discriminant function analysis, the proportion of individuals classified into their original groups was 97 and 100% for up- and downstream populations, respectively. Principal component analysis of morphometric data demonstrated that the up- and downstream samples of Siah-Mahi are clearly distinct. In the genetic analysis, 6 informative primers produced 89 polymorphic bands with 95% polymorphism. In association analysis between morphological and genetic data, 63 of 89 genetic markers were significantly correlated with the 16 morphometric characters. We conclude that these are 2 morphologically and genetically distinct populations of C. c. gracilis, probably due to limited downstream dispersal and elimination of upstream migration.

Due to the miscegenation of the Brazilian population, the central region of Brazil was colonized by internal migration of individuals from different origins, who contributed to the genetic diversity existing in this population. The purpose of this study was to estimate population parameters based on the allele frequencies for 15 polymorphic autosomal short-tandem repeat (STR) loci present in the population of the State of Goiás in the central region of Brazil, and to compare the results with those of others from different Brazilian populations. DNA was obtained from a sample of 986 unrelated individuals by a commercial reagent kit and was quantified by spectrometry for later amplification in the thermocycler. These loci, commonly used in forensics and paternity testing, reflected Hardy-Weinberg equilibrium in this population. The D18S51 and Penta E loci had the highest number of alleles, while the observed heterozygosity reached the highest rates in FGA (0.920), D7S820 (0.870), and vWA (0.867) markers. Genetic diversity reached the highest levels in Penta E (0.906), Penta D (0.873), and D18S51 (0.860) markers, and the investigated forensic parameters showed high average values, with 93% power of discrimination, polymorphism information content of 78%, gene diversity of 79%, and observed heterozygosity of 79%. Similar to the other populations of Brazil, the population of the Midwest is derived from the admixture of 3 main parental groups: Amerindian, European, particularly Portuguese, and Africans from sub-Saharan Africa. In this context, the overall distribution of allele frequencies in the STR markers of various Brazilian populations is quite similar to the data obtained in this study.

The frequency of micronuclei in both buccal cells and peripheral blood lymphocytes is extensively used as a biomarker of chromosomal damage and genome stability in human populations. We examined whether prolonged exposure to complex mixtures of pesticides leads to an increase in cytogenetic damage. The exposed group comprised 50 agricultural aviators, mainly from Central and Southeast regions of Brazil, who had inhaled agrochemicals for more than 10 years without personal protection equipment; the control group consisted of 17 men from the same regions, without indication of exposure to pesticides, There were three times higher frequencies of micronuclei (P < 0.05) and 2.5 times higher frequencies of binucleated cells in the aviators when compared to controls. However, cytotoxic alterations such as broken eggs and karyorrhexis did not present statistically significant differences between the exposed and control groups. Therefore, diverse agrochemicals used to combat pests in agriculture possess genotoxic effects in the oral mucosa of the agricultural pilots, as showed in this study.

Specific genotypes appear to be related to the development of thyroid disease. We examined whether polymorphisms of the genes CYP1A1, GSTM1, GSTT1, and TP53 at codon 72 are associated with increased risk for thyroid nodules. Blood samples were obtained from 122 thyroid patients with nodules and from 134 healthy control individuals from Goiânia city, GO, Brazil. We found no significant association of CYP1A1m1 and CYP1A1m2 genotypes with thyroid diseases (P > 0.05). The null genotypes of GSTM1 and GSTT1 genes were predominant in patients with nodules, indicating that individuals that possess these genotypes have a predisposition for thyroid disease. The genotype p53Arg Arg was associated with a low risk for thyroid cancer (OR = 0.15; P < 0.0001), indicating that the arginine allele in homozygosis could have a protective effect against carcinogenesis. On the other hand, the p53ArgPro genotype was significantly associated with malignant neoplastic nodules (OR = 3.65; P = 0.001). Interindividual variation in susceptibility to thyroid diseases could provide new perspectives for early diagnosis, prognosis and treatment, indicating which patients with thyroid nodules will benefit from treatment, depending on specific polymorphic profiles.

The androgen receptor is encoded by a single-copy gene located in the long arm of the X chromosome (Xq11-12); it consists of eight exons and encodes an intracellular transcription factor that belongs to the steroid/nuclear receptor superfamily. Disturbances in the function of the androgen receptor can lead to several forms of male pseudohermaphroditism, such as androgen insensitivity syndrome, which can lead to infertility. Infertility affects around 20% of couples, and in half of the cases it is a male problem. Seventy male patients with idiopathic infertility were selected; data were obtained on age, drinking and smoking habits, occupation, and family history. The mean age of the patients was 37 years old (standard deviation = 12.3); 44% were azoospermic, 33% were oligozoospermic and 24% did not have alterations in the spermogram. Our objective was to evaluate a possible association between male infertility and mutations in the androgen receptor gene based on the presence or absence of exons 1 and 4 of this gene. These two exons were tested by PCR, and their products were separated on 1.5% agarose gels. We found that azoospermic patients had higher mutation rates on exons 1 and 4 of the androgen receptor gene, when compared to other alterations that also lead to infertility, such as oligozoospermia and teratozoospermia. So, we conclude that patients who do not produce sperm have a higher number of mutations in the androgen receptor gene when compared to those who only have impaired sperm production. Based on molecular analysis, we found that there was no correlation between alterations in the spermogram and mutations on exons 1 and 4 of the androgen receptor gene and no association between alterations in the spermogram and alcohol drinking or smoking.

In September 1987, in Goiânia, Brazil, one of the most serious radiological accidents occurred at a radiation therapy unit involving a source of cesium-137. The current study examined the occurrence of possible germline mutations at the AZF region of the exposed men and in their male offspring. Genomic DNA samples of 16 individuals were analyzed for microdeletions. All exposed individuals amplified sequence tagged sites; however, sY84 and sY86 showed a duplication in 75% (12/16) of the exposed group. Exposed families designated as B and E showed a duplication of sY84 and sY86, both in the fathers and their sons. Fathers of families A, C, D, and F did not show a duplication in the AZF region, but their sons did. The children in A and D had duplications of sY84 and sY86, while children in families C and F had a duplication exclusively of sY84. Family G showed a duplication of sY84 in all three generations from grandfather to grandson. Two human endogenous retroviral sequences (HERV) exist in the AZFa region, and non-allelic recombination between these sequences could cause chromosomal rearrangements, such as deletions or duplications, and a mutational mechanism intrinsic to non-allelic recombination could be increased by individual exposure to ionizing radiations from cesium-137. Consequently, the hotspots inside HERV mediated recombination in AZFa, and the duplication diversity was compatible with male fertility, since to date, none of the exposed individuals have demonstrated fertility disorders.