RESUMEN
Requests for solving complex kinship casework involving at least one female are increasing and in these circumstances the analysis of X-chromosomal STR markers plays a relevant role. Actually, it is well known the superior statistical power of X-STRs compared to autosomal markers in solving relationship when two sisters or half-sisters are involved and none of parents is available, in maternity testing or in cases involving close relatives as alternative putative fathers. In addition, the possibility to amplify more loci simultaneously and the strategy based on the analysis of four linkage groups to obtain the X-haplotype provide a powerful and validated tool. Nevertheless, haplotypes frequency distribution in different populations is still needed for calculation of probabilities in relationship testing. Published haplotype frequencies from German population data are available, but in different caseworks we found unreported X-haplotypes. To enlarge the forensic X-chromosome database, we present haplotype frequencies and other parameter of forensic interest obtained from 200 anonymous DNA samples of unrelated Italian males for the four linkage groups included in the Investigator Argus X-12 kit. From the comparison of the Italian sample haplotype frequencies with other populations, significant genetic distances were found with Asian and African populations, but not with Europeans. Finally, casework examples of complex kinship analysis are presented.
Asunto(s)
Cromosomas Humanos X , Bases de Datos Genéticas , Genética Forense , Ligamiento Genético , Haplotipos , Humanos , Italia , Repeticiones de Microsatélite/genéticaRESUMEN
The extensively polymorphic CYP2B6 gene metabolizes endogenous and exogenous compounds, among which are nicotine and bupropion, although its contribution to the systemic metabolism of nicotine still remains controversial. In the present study, the distribution of the CYP2B6 variant and genotype frequencies were analyzed in a sample of 202 Italian individuals who were also invited to answer the Fagerström test for nicotine dependence (FTND), in an effort to assess the involvement of CYP2B6 polymorphisms in nicotine dependence. Eight single-nucleotide polymorphisms of CYP2B6 were tested and seven different variants were identified showing frequencies similar to the European population. The reduced activity of the CYP2B6*6 variant was significantly (p=0.025) distributed among the nicotine-dependent individuals compared to non-nicotine dependents. Also, the CYP2B6*1/*6 genotype achieved statistical significance (p=0.016) within the nicotine-dependent individuals. The high occurrence of CYP2B6*6 carriers among nicotine-dependent individuals may suggest a possible involvement in nicotine dependence, with a potential impact on smoking cessation treatments tailored to the individual smoker's genotype.
Asunto(s)
Alelos , Citocromo P-450 CYP2B6/genética , Polimorfismo de Nucleótido Simple , Tabaquismo/genética , Biotransformación/genética , Citocromo P-450 CYP2B6/fisiología , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Italia/epidemiología , Muestreo , Encuestas y Cuestionarios , Tabaquismo/epidemiologíaRESUMEN
CYP2D6 polymorphism analysis is gaining increasing interest in forensic pharmacogenetics. Nevertheless, DNA recovered from forensic samples could be of poor quality and not suitable for long polymerase chain reaction required to type CYP2D6 gene prior to SNaPshot minisequencing analysis performed to define alleles with different enzymatic activity. We developed and validated following the guidelines of the Scientific Working Group on DNA Analysis Methods a tetraplex PCR yielding four amplicons of 597, 803, 1142, and 1659 bp encompassing the entire CYP2D6 gene to analyze eleven SNP positions by SNaPshot minisequencing. Concordance, sensitivity, and specificity were assessed. The method, applied to thirty-two forensic samples failed to amplify with long PCR, allowed the amplification of CYP2D6 gene in 62.5% of degraded samples. The new tetraplex PCR appears a suitable method for CYP2D6 analysis in forensic pharmacogenetics.
Asunto(s)
Citocromo P-450 CYP2D6/genética , Degradación Necrótica del ADN , Genotipo , Reacción en Cadena de la Polimerasa Multiplex/métodos , Polimorfismo de Nucleótido Simple , Genética Forense , Humanos , Farmacogenética , Sensibilidad y EspecificidadRESUMEN
Pharmacogenetic testing of drug metabolizing enzyme polymorphisms provides an important tool to improve prescribing decisions, avoiding therapeutic failure and adverse drug reactions. Cytochrome P450 2D6 isoform plays an important role in the metabolism of about 20%-25% of widely used clinical drugs. Interethnic differences in allele frequency distribution of the CYP2D6 gene are well established, but interethnic admixture, introducing variations in population ancestry and resulting in distinct levels of population structure, should be acknowledged in pharmacogenomic studies to avoid inappropriate extrapolation of CYP2D6 data. The aim of the present research was to characterize CYP2D6 polymorphism in a random sample of 122 natives and 175 immigrants from Africa, Asia, and South America living in the Emilia-Romagna region (Italy), considering the present scenario of immigration and back migration events, which is a source of admixture. The results are today consistent with the known interethnic genetic variation, but the observed significant divergence between natives and Africans or South-East Asians predicts that admixture will reshape the population structure and the native metabolic ratio curve requiring, for drug prescription and pharmacogenetics studies, an interdisciplinary approach applied in an appropriate biogeographical and anthropological frame.
Asunto(s)
Pueblo Asiatico/genética , Población Negra/genética , Citocromo P-450 CYP2D6/genética , Variación Genética , Población Blanca/genética , Alelos , Pueblo Asiatico/etnología , Población Negra/etnología , Emigrantes e Inmigrantes , Femenino , Frecuencia de los Genes , Técnicas de Genotipaje/métodos , Humanos , Italia/etnología , Masculino , Población Blanca/etnologíaRESUMEN
The distribution of Y chromosomal haplotypes and haplogroups in two different population samples from the Romagna region (North Italy) was performed. One population sample was collected in the urban area of Rimini, an ancient port in Roman age and the other one in the near and geographically more isolated rural area of Valmarecchia. Fast and slow evolving markers have been studied to infer population history and to analyse the microgeographic heterogeneity of Y chromosome in a Northern Italian region. Haplotype variability values compared to those observed in a Central Italy sample from the other side of Apennine mountains and in an Austrian population sample were very similar.
Asunto(s)
Cromosomas Humanos Y , Genética de Población , Haplotipos , Dermatoglifia del ADN , Frecuencia de los Genes , Humanos , Italia , Masculino , Reacción en Cadena de la Polimerasa , Población Rural , Secuencias Repetidas en Tándem , Población UrbanaRESUMEN
Microsatellites or short tandem repeats (STRs) markers are important tools for mapping disease-causing genes by linkage, for performing investigations in forensic medicine, for population genetic studies and for studying genetic modifications in tumors. In forensic applications neoplastic tissues can be used as a source of genetic information for personal identification or paternity testing when no other specimen is available. Cancer tissues can show microsatellite instability (MSI) and loss of heterozygosity (LOH) also for the STRs used in the forensic field. In this study, we screened 56 sporadic gastrointestinal carcinomas in order to provide further data for the evaluation of the incidence of allelic alterations for 15 STR loci and the suitability of using cancerous tissues in forensic applications. Sixty-six percent of the cancerous tissues were found to possess allelic alterations of the microsatellites analyzed with a high incidence of MSI-L (microsatellite instability low) when compared to the corresponding normal tissue. The most frequently altered loci were D18S51, VWA, and FGA. From a forensic perspective, great care must be taken in evaluating the DNA typing results obtained from cancerous tissue samples.
Asunto(s)
Genética Forense , Neoplasias/genética , Estudios de Cohortes , Neoplasias Gastrointestinales/genética , Neoplasias Gastrointestinales/patología , Marcadores Genéticos , Humanos , Pérdida de Heterocigocidad , Inestabilidad de Microsatélites , Neoplasias/patologíaRESUMEN
Duffy and ABO blood group genetic polymorphisms were studied by minisequencing analysis of single-nucleotide polymorphisms (SNPs) at nucleotide positions--33, 125, 265, and 298 of the Duffy gene and at nucleotide positions-261, 297, 467, 646, and 703 of the ABO gene. In an Italian population sample, we found four alleles and seven genotypes for the Duffy and six alleles and 16 genotypes for the ABO systems. The lower limit for reproducible results was 200 pg DNA, with a range of up to 10 ng and an optimum at 1 ng. All of the 16 analyzed inclusive paternity tests were also consistent with parentage and two out of four inconsistencies with parentage cases were excluded by one or more SNPs. Although Duffy and ABO SNP typing show lower informativeness than most current forensic tests, their robustness, the limited population distribution of FY* Fy type, and the sensitivity of the minisequencing technology suggest that these markers can be useful in selected forensic applications.
Asunto(s)
Sistema del Grupo Sanguíneo ABO/genética , Sistema del Grupo Sanguíneo Duffy/genética , Paternidad , Alelos , Cartilla de ADN , Genotipo , Humanos , Italia , Masculino , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , Análisis de SecuenciaRESUMEN
Many X-chromosome short tandem repeats (X-STRs) have been validated for forensic use even if further studies are needed on allele frequencies and mutation rates to evaluate the extent of polymorphism in different populations and to establish reference databases useful for forensic applications and for anthropological studies. A single multiplex reaction of seven X-STRs, which includes the DXS6789, HUMARA, DXS10011, DXS7423, HPRTB, DXS6807, DXS101 loci, is presented and their allele frequency distribution in a large population sample including 556 subjects (268 females and 288 males) analysed by five forensic laboratories of Central and Northern Italy is shown. Our results demonstrate the feasibility of a single amplification/detection reaction involving seven markers of the X chromosome, which can be fruitfully used in complex kinship analysis.