Distribution of the CCR5delta32 allele (gene variant CCR5) in Rondônia, Western Amazonian region, Brazil

Since around 1723, on the occasion of its initial colonization by Europeans, Rondonia has received successive waves of immigrants. This has been further swelled by individuals from northeastern Brazil, who began entering at the beginning of the twentieth century. The ethnic composition varies across the state according to the various sites of settlement of each wave of immigrants. We analyzed the frequency of the CCR5L32 allele of the CCR5 chemokine receptor, which is considered a Caucasian marker, in five sample sets from the population. Four were collected in Porto Velho, the state capital and the site of several waves of migration. Of these, two, from the Hospital de Base were comprised of HB Mothers and HB Newborns presenting allele frequencies of 3.5 percent and 3.1 percent, respectively, a third from the peri-urban neighborhoods of Candelária/Bate-Estaca (1.8 percent), whereas a fourth, from the Research Center on Tropical Medicine/CEPEM (0.6 percent), was composed of malaria patients under treament. The fifth sample (3.4 percent) came from the inland Quilombola village of Pedras Negras. Two homozygous individuals (CCR5Δ32/CCR5Δ32) were detected among the HB Mother samples. The frequency of this allele was heterogeneous and higher where the European inflow was more pronounced. The presence of the allele in Pedras Negras revealed European miscegenation in a community largely comprising Quilombolas.

Y-STR diversity and ethnic admixture in White and Mulatto Brazilian population samples

We investigated 50 Mulatto and 120 White Brazilians for the Y-chromosome short tandem repeat (Y-STR) markers (DYS19, DYS390, DYS391, DYS392 and DYS393) and found 79 different haplotypes in the White and 35 in the Mulatto sample. Admixture estimates based on allele frequencies showed that the admixture of the white sample was 89 percent European, 6 percent African and 5 percent Amerindian while the Mulatto sample was 93 percent European and 7 percent African. Results were consistent with historical records of the directional mating between European males and Amerindian or African females.

Distrofia miotônica tipo 1 em pacientes com catarata: diagnóstico molecular para triagem e aconselhamento genético / Myotonic dystrophy type 1 in cataract patients: Molecular diagnosis for screening and genetic counseling

OBJETIVOS: Detectar novos pacientes portadores da mutação e pré-mutação da DM1, entre pacientes com catarata e realizar aconselhamento genético. MÉTODOS: Foi estudado o DNA de 60 pacientes, por meio da análise por reação em cadeia de polimerase. Este estudo foi realizado no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto e os pacientes foram selecionados a partir dos atendimentos realizados no Ambulatório de Catarata do Departamento de Oftalmologia, entre 01/01/1982 a 30/06/1995. Os critérios de seleção foram pacientes com menos de 55 anos, com catarata bilateral, sem fator causal que justificasse a lesão, exceto por diabete melito tipo 2 com ou sem sinais neuromusculares sugestivos de distrofia miotônica. RESULTADOS: Foram encontrados 3 pacientes com a mutação completa, correspondendo a 5 por cento da amostra. Nenhum portador da pré-mutação foi encontrado. A partir dos pacientes diagnosticados, outros familiares afetados foram detectados. CONCLUSÕES: Este estudo enfatiza a importância da triagem de distrofia miotônica tipo 1 (DM1) entre pacientes com catarata, e mostra, também, a importância do aconselhamento genético destes pacientes.

The SCA1 (Spinocerebellar ataxia type 1) and MJD (Machado-Joseph disease) CAG repeats in normal individuals: segregation analysis and allele frequencies

Spinocerebellar ataxia type 1 (SCA1) and Machado-Joseph disease (MJD/SCA3) are autosomal dominant neurodegenerative diseases caused by expansions of a CAG trinucleotide repeat in the SCA1 and MJD genes. These expanded sequences are unstable upon transmission, leading to an intergeneration increase in the number of repeats (dynamic mutation). The transmission of the CAG repeat was studied in normal mother-father-child trios, referred for paternity testing (SCA1, n = 367; MJD, n = 879). No segregation distortion was detected. The CAG allele frequencies were determined in 330 unrelated individuals (fathers from couples tested for paternity). The allele frequency distributions did not differ from those previously reported for European populations. The estimated values for the statistic parameters indicating diversity at the SCA1 locus did not differ much from those reported previously for other STRs in the Brazilian population, while those for the MJD locus were close to or higher than the maximum values of previous reports. This shows that SCA1 and MJD are highly informative loci for applications in genetic and population studies and for forensic analysis

Procedimentos em exumaçöes para investigaçäo de vínculo genético em ossos / Exhumations procedures for investigating the genetic link in bones

OBJETIVO: Identificar problemas técnicos nas exumaçöes para pesquisa de DNA em ossos e propor soluçöes por meio de protocolo. MÉTODOS: Estudo prospectivo e qualitativo das exumaçöes, procedendo cada etapa da perícia conforme proposto na literatura médico-legal. Foram realizadas dez exumaçöes no período de 1995 a 1998, para coleta de restos humanos e extraçäo do DNA, sendo sete de interesse civil e três, criminal. As dificuldades técnicas surgidas na execuçäo desses procedimentos foram resolvidas a partir de alternativas estabelecidas. RESULTADOS: A escassez de informaçöes úteis para a identificaçäo do indivíduo, baseada em seus restos mortais, foi observada em todos os casos. As características morfológicas individuais contribuíram para a identificaçäo em 50 por cento dos casos. O auxílio dos familiares foi importante na revelaçäo dessas características. Em três casos, foi indicado apenas o sexo e, em um, a idade. A falta de infra-estrutura dos cemitérios e de segurança policial dificultou o trabalho pericial. CONCLUSOES: Para garantir a fidelidade do exame molecular do DNA é necessário identificar de quem säo os restos mortais a serem exumados. Para a eficiência da perícia, é fundamental o uso de um protocolo que inclua, entre outras questöes, as relativas a identificaçäo, infra-estrutura e segurança pessoal dos peritos no local do exame