28 research outputs found
Lack of association between genetic polymorphisms in IGF1 and IGFBP3 with twin births in a Brazilian population (Cândido Godói, Rio Grande do Sul)
Insulin-like growth factor (IGF-1) is an important peptide hormone involved in the reproduction and fetal development of mammals, and it is suggested that it may influence the human twinning rate. This study aimed to test such possible association, investigating the genetic polymorphisms IGF1 (CA)n and IGFBP3 rs2854744 in the population from Candido Godoi (CG), a small city located in the South of Brazil that has a high prevalence of twin births. A case-control study was performed comprising a total of 39 cases (representing about 40% of the mothers of twins who were born in CG after 1995) and 214 controls (mothers of non-twin children), 97 of whom were living in CG while 117 were living in Porto Alegre. DNA was extracted from blood leucocytes and genotyping was performed. According to the statistical analyses, there was no significant difference in the frequencies of both studied genetic polymorphisms when comparing case group with control group. Thus, our results pointed to a lack of association between IGF1 (CA)n and IGFBP3 rs2854744 polymorphisms and twin births in CG, but further investigations in other populations with different characteristics must be performed to confirm the role of IGF-I in human twinning
How strong was the bottleneck associated to the peopling of the Americas? New insights from multilocus sequence data
In spite of many genetic studies that contributed for a deep knowledge about the peopling of the Americas, no consensus
has emerged about important parameters such as the effective size of the Native Americans founder population.
Previous estimates based on genomic datasets may have been biased by the use of admixed individuals from
Latino populations, while other recent studies using samples from Native American individuals relied on approximated
analytical approaches. In this study we use resequencing data for nine independent regions in a set of Native
American and Siberian individuals and a full-likelihood approach based on isolation-with-migration scenarios accounting
for recent flow between Asian and Native American populations. Our results suggest that, in agreement
with previous studies, the effective size of the Native American population was small, most likely in the order of a few
hundred individuals, with point estimates close to 250 individuals, even though credible intervals include a number as
large as ~4,000 individuals. Recognizing the size of the genetic bottleneck during the peopling of the Americas is important
for determining the extent of genetic markers needed to characterize Native American populations in genome-wide
studies and to evaluate the adaptive potential of genetic variants in this population
Decifrando o “mistério dos gêmeos”: Vinte anos de pesquisa em Cândido Godói, Rio Grande do Sul
Cândido GodĂłi (CG) Ă© um pequeno municĂpio brasileiro localizado no noroeste do Rio Grande do Sul e Ă© conhecido como “Cidade dos GĂŞmeos” devido Ă alta taxa de nascimentos gemelares na regiĂŁo. Diante de um fato tĂŁo notável, muitas explicações foram sugeridas. Entre estas teorias, a que mais recebeu atenção da mĂdia, mesmo sem base cientĂfica, foi a de que a gemelaridade seria fruto de experimentos de um mĂ©dico nazista alemĂŁo foragido apĂłs a Segunda Guerra Mundial. A convite da prĂłpria comunidade de CG, nosso grupo de pesquisa trabalha para resolver este mistĂ©rio desde 1994, analisando diferentes fatores possivelmente relacionados, em especial suas caracterĂsticas genĂ©ticas. Aqui, nĂłs sumarizamos os principais resultados obtidos em mais de duas dĂ©cadas de pesquisa, com foco nas particularidades do processo de comunicação dos resultados, aspectos Ă©ticos e como os achados cientĂficos naquela comunidade contribuem nĂŁo apenas com a resolução de um mistĂ©rio histĂłrico e local, mas tambĂ©m com o estudo de outras questões, como a reprodução humana e as bases biolĂłgicas da gemelaridade.Palavras-chave: INaGeMP; gĂŞmeos; efeito fundador; isolamento reprodutivo; fertilidade; genĂ©tica mĂ©dica populaciona
Population medical genetics : translating science to the community
Rare genetic disorders are currently in the spotlight due to the elevated number of different conditions and significant total number of affected patients. The study of these disorders is extremely helpful for the elucidation of physiological processes related with complex disorders. Isolated populations are instrumental for the study of genetic disorders, considering their homogeneity and high proportion of affected patients in a small geographic area. These favorable conditions lead to the creation of a new discipline, known as "population medical genetics", which integrates medical genetics, population genetics, epidemiological genetics and community genetics. In order to develop practical activities in this new discipline, the National Institute of Population Medical Genetics (INaGeMP) was created in 2008 in Brazil. INaGeMP has developed several tools and funded numerous research activities. In this review, we highlight three successful projects developed in the first 10 years of INaGeMP activities (2008-2018): a newborn screening pilot study for MPS VI in Northeast Brazil, the study of Machado-Joseph disease in Brazilian families with Azorian ancestry, and the high twinning rate in a small town in southern Brazil. The results of these projects in terms of scientific output and contributions to the affected communities highlight the success and importance of INaGeMP
Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?
Cândido Godói (CG) is a small municipality in South Brazil with approximately 6,000 inhabitants. It is known as the “Twins' Town” due to its high rate of twin births. Recently it was claimed that such high frequency of twinning would be connected to experiments performed by the German Nazi doctor Joseph Mengele. It is known, however, that this town was founded by a small number of families and therefore a genetic founder effect may represent an alternatively explanation for the high twinning prevalence in CG. In this study, we tested specific predictions of the “Nazi's experiment” and of the “founder effect” hypotheses. We surveyed a total of 6,262 baptism records from 1959–2008 in CG catholic churches, and identified 91 twin pairs and one triplet. Contrary to the “Nazi's experiment hypothesis”, there is no spurt in twinning between the years (1964–1968) when Mengele allegedly was in CG (P = 0.482). Moreover, there is no temporal trend for a declining rate of twinning since the 1960s (P = 0.351), and no difference in twinning among CG districts considering two different periods: 1927–1958 and 1959–2008 (P = 0.638). On the other hand, the “founder effect hypothesis” is supported by an isonymy analysis that shows that women who gave birth to twins have a higher inbreeding coefficient when compared to women who never had twins (0.0148, 0.0081, respectively, P = 0.019). In summary, our results show no evidence for the “Nazi's experiment hypothesis” and strongly suggest that the “founder effect hypothesis” is a much more likely alternative for explaining the high prevalence of twinning in CG. If this hypothesis is correct, then this community represents a valuable population where genetic factors linked to twinning may be identified
Análise genética e epidemiológica na cidade de Cândido Godói - RS, a "Terra dos Gêmeos"
A gemelaridade em humanos Ă© um evento de etiologia complexa, cujas causas ainda nĂŁo sĂŁo totalmente conhecidas. Fatores ambientais como idade materna avançada, aumento da paridade, fatores hormonais e reprodução assistida, entre outros, estĂŁo associados a gestações de gĂŞmeos dizigĂłticos (DZ). Ao contrário, há poucas evidĂŞncias de fatores ambientais relacionados a gemelaridade monozigĂłtica (MZ). Apesar dos avanços tecnolĂłgicos na área da genĂ©tica, ainda Ă© escasso o conhecimento sobre os fatores genĂ©ticos envolvidos na etiologia da gemelaridade. NĂŁo existem claras associações de fatores genĂ©ticos com gestações de gĂŞmeos MZ. Por outro lado, estudos mostram a influĂŞncia de vários genes na gemelaridade DZ e genes que possam influenciar a poli-ovulação, a implantação e o desenvolvimento dos embriões sĂŁo bons candidatos para estudos genĂ©ticos. A cidade de Cândido GodĂłi (CG), localizada no noroeste do Rio Grande do Sul, Ă© conhecida como a “Terra dos GĂŞmeos” devido a sua alta incidĂŞncia de nascimentos gemelares. Recentemente a teoria de que os gĂŞmeos de CG sĂŁo produto de experimentos do mĂ©dico nazista Josef Mengele ganhou ampla divulgação pela imprensa. PorĂ©m, a histĂłria de CG sugere que fatores genĂ©ticos, potencializados por um efeito fundador ocorrido durante a colonização do municĂpio, sejam responsáveis pelos recorrentes nascimentos duplos na cidade. Esse trabalho teve como objetivos testar a plausibilidade da “teoria do mĂ©dico nazista” e investigar possĂveis genes relacionados com a gemelaridade em CG. Para isso, foram analisados os livros de batismos das Igrejas catĂłlicas do municĂpio, os sobrenomes e as histĂłrias familiares da amostra de mulheres coletadas para os testes genĂ©ticos. Foram investigados polimorfismos em genes envolvidos no mecanismo de ovulação (Ser680Arg do gene FSHR), no desenvolvimento do embriĂŁo (677 C!T do gene MTHFR) e na implantação do blastocisto (P72R do gene TP53, rs1563828 no gene MDM4, SNP309 do gene MDM2, rs1529916 no gene USP7 e rs929271 do gene LIF, todos da rota da p53) em 42 mĂŁes de gĂŞmeos e 101 mulheres que sĂł tiveram gestações Ăşnicas, todas naturais de CG.Todos os polimorfismos foram identificados pelo sistema TaqMan de discriminação alĂ©lica atravĂ©s de PCR em tempo real. Foram realizados testes de zigosidade em 41 pares de gĂŞmeos residentes de CG com o kit Identifilier da Applied Bisystems. A partir das análises epidemiolĂłgicas, demonstrou-se que a ocorrĂŞncia de nascimentos de gĂŞmeos em CG Ă© frequente desde o inĂcio do sĂ©culo XX, mais especificamente em uma comunidade deste municĂpio, chamada Linha SĂŁo Pedro, o que reforça a idĂ©ia de um efeito fundador. NĂŁo há associação entre gemelaridade em Cândido GodĂłi e os polimorfismos estudados dos genes FSHR e MTHFR. Em compensação, foi observada associação dos alelos P72 do gene TP53 e o alelo T do gene MDM4 com gemelaridade. Estudos sugerem que esses alelos, alĂ©m de estarem envolvidos nos mecanismos de supressĂŁo tumoral, estariam relacionados com infertilidade, sendo este, portanto, um resultado bastante interessante. Por serem alelos que resultam em apoptose menos eficiente, uma hipĂłtese Ă© que esses polimorfismos possuam um papel importante no perĂodo pĂłs-implantação, “permitindo” o desenvolvimento de dois embriões quando o mais comum seria a eliminação de pelo menos um. Trabalhos demonstrando que camundongos com apoptose deficiente mantĂŞm em maior porcentagem suas gestações e que, a combinação do alelo P72 com genĂłtipos selvagens de MDM2 e LIF altera a probabilidade de sobrevivĂŞncia de bebĂŞs do sexo masculino, sĂŁo evidĂŞncias que contribuem para essa hipĂłtese. É importante salientar que esses resultados foram observados em uma população pequena, de origem Ă©tnica definida, contribuindo com apenas uma pequena fração do componente genĂ©tico da herdabilidade da gemelaridade. Mais estudos devem ser realizados em coortes maiores e grupos com diferentes backgrounds genĂ©ticos. No entanto, eles sugerem uma explicação genĂ©tica para o grande aumento na taxa de gemelaridade em CG e tambĂ©m apontam para uma possĂvel nova função dos genes da rota da p53 na reprodução humana.Twinning in humans is a complex etiology event, whose causes are not completely understood. Environmental factors such as advanced maternal age, increased parity, assisted reproduction and hormonal factors, among others, are associated with dizygotic twin pregnancies. Instead, there is little evidence of environmental factors related to monozygotic twins. Despite technological advances in genetics, it is still little knowledge about the genetic factors involved in the etiology of twin pregnancy. There are no clear associations between genetic factors and MZ twin pregnancies. On the other hand, studies show the influence of several genes in DZ twinning and genes that may influence the polyovulation, implantation and embryo development are good candidates for genetic studies. Cândido GodĂłi (CG), located in northwestern of Rio Grande do Sul, is known as the "Twins’ Town" because of its high incidence of twin births. Recently the theory that the twins are product of experiments of Nazi doctor Josef Mengele gained wide dissemination by the press. However, the history of CG suggests that genetic factors, fueled by a founder effect occurred during the colonization of the municipality, are responsible for the recurrent double births in the city. This study aimed to test the plausibility of the "theory of Nazi doctor" and investigate possible genes related to multiple births in CG. For this, we analyzed the baptisms’ books of Catholic Churches of the city, the family histories and surnames of women in the sample collected for genetic testing. We investigated polymorphisms in genes involved in the mechanism of ovulation (Ser680Arg FSHR gene), in the embryo development (677 C ! T MTHFR gene) and in blastocyst implantation (P72R TP53 gene, rs1563828 in MDM4 gene, SNP309 in MDM2 gene, rs1529916 in USP7 gene and rs929271 in LIF gene, all in p53 pathway) in 42 mothers of twins and 101 women who had only singleton pregnancies, all natural of CG. All polymorphisms were identified by the system TaqMan of allelic discrimination by real-time PCR. Zygosity tests were performed in 41 pairs of twins residing in CG by the Applied Identifilier Bisystems. Epidemiological studies show that twin births in CG are recurrent since the beginning of the twentieth century, specifically in a community of this municipality, called Linha SĂŁo Pedro, which reinforces the idea of a founder effect. There are no association between SNPs on FSHR and MTHFR genes and twinning. Nevertheless P72 allele of TP53 gene and T allele of MDM4 gene are associated with twinning in our study. Studies suggest that these alleles are not just involved with tumor suppression, but would be related to infertility, which is therefore a very interesting result. These alleles result in a less efficient apoptosis, therefore, a hypothesis is that these polymorphisms have an important role in post-implantation period, "allowing" the development of two embryos when the most common outcome would be the elimination of at least one. Studies demonstrating that mice with deficient apoptosis keep a greater percentage of their pregnancies, and that the combination of the P72 allele with wild genotypes of MDM2 and LIF change the probability of survival of male babies are a contributing evidence for this hypothesis. Importantly, these results were observed in a small population of defined ethnic origin, contributing only with a small fraction of the genetic component of heritability of multiple births. Further studies should be conducted in larger cohorts and groups with different genetic backgrounds. However, our results suggest a genetic explanation for the increased twinning rate in CG and also point to a possible new function of the route of the p53 gene in human reproduction
Análise genética e epidemiológica na cidade de Cândido Godói - RS, a "Terra dos Gêmeos"
A gemelaridade em humanos Ă© um evento de etiologia complexa, cujas causas ainda nĂŁo sĂŁo totalmente conhecidas. Fatores ambientais como idade materna avançada, aumento da paridade, fatores hormonais e reprodução assistida, entre outros, estĂŁo associados a gestações de gĂŞmeos dizigĂłticos (DZ). Ao contrário, há poucas evidĂŞncias de fatores ambientais relacionados a gemelaridade monozigĂłtica (MZ). Apesar dos avanços tecnolĂłgicos na área da genĂ©tica, ainda Ă© escasso o conhecimento sobre os fatores genĂ©ticos envolvidos na etiologia da gemelaridade. NĂŁo existem claras associações de fatores genĂ©ticos com gestações de gĂŞmeos MZ. Por outro lado, estudos mostram a influĂŞncia de vários genes na gemelaridade DZ e genes que possam influenciar a poli-ovulação, a implantação e o desenvolvimento dos embriões sĂŁo bons candidatos para estudos genĂ©ticos. A cidade de Cândido GodĂłi (CG), localizada no noroeste do Rio Grande do Sul, Ă© conhecida como a “Terra dos GĂŞmeos” devido a sua alta incidĂŞncia de nascimentos gemelares. Recentemente a teoria de que os gĂŞmeos de CG sĂŁo produto de experimentos do mĂ©dico nazista Josef Mengele ganhou ampla divulgação pela imprensa. PorĂ©m, a histĂłria de CG sugere que fatores genĂ©ticos, potencializados por um efeito fundador ocorrido durante a colonização do municĂpio, sejam responsáveis pelos recorrentes nascimentos duplos na cidade. Esse trabalho teve como objetivos testar a plausibilidade da “teoria do mĂ©dico nazista” e investigar possĂveis genes relacionados com a gemelaridade em CG. Para isso, foram analisados os livros de batismos das Igrejas catĂłlicas do municĂpio, os sobrenomes e as histĂłrias familiares da amostra de mulheres coletadas para os testes genĂ©ticos. Foram investigados polimorfismos em genes envolvidos no mecanismo de ovulação (Ser680Arg do gene FSHR), no desenvolvimento do embriĂŁo (677 C!T do gene MTHFR) e na implantação do blastocisto (P72R do gene TP53, rs1563828 no gene MDM4, SNP309 do gene MDM2, rs1529916 no gene USP7 e rs929271 do gene LIF, todos da rota da p53) em 42 mĂŁes de gĂŞmeos e 101 mulheres que sĂł tiveram gestações Ăşnicas, todas naturais de CG.Todos os polimorfismos foram identificados pelo sistema TaqMan de discriminação alĂ©lica atravĂ©s de PCR em tempo real. Foram realizados testes de zigosidade em 41 pares de gĂŞmeos residentes de CG com o kit Identifilier da Applied Bisystems. A partir das análises epidemiolĂłgicas, demonstrou-se que a ocorrĂŞncia de nascimentos de gĂŞmeos em CG Ă© frequente desde o inĂcio do sĂ©culo XX, mais especificamente em uma comunidade deste municĂpio, chamada Linha SĂŁo Pedro, o que reforça a idĂ©ia de um efeito fundador. NĂŁo há associação entre gemelaridade em Cândido GodĂłi e os polimorfismos estudados dos genes FSHR e MTHFR. Em compensação, foi observada associação dos alelos P72 do gene TP53 e o alelo T do gene MDM4 com gemelaridade. Estudos sugerem que esses alelos, alĂ©m de estarem envolvidos nos mecanismos de supressĂŁo tumoral, estariam relacionados com infertilidade, sendo este, portanto, um resultado bastante interessante. Por serem alelos que resultam em apoptose menos eficiente, uma hipĂłtese Ă© que esses polimorfismos possuam um papel importante no perĂodo pĂłs-implantação, “permitindo” o desenvolvimento de dois embriões quando o mais comum seria a eliminação de pelo menos um. Trabalhos demonstrando que camundongos com apoptose deficiente mantĂŞm em maior porcentagem suas gestações e que, a combinação do alelo P72 com genĂłtipos selvagens de MDM2 e LIF altera a probabilidade de sobrevivĂŞncia de bebĂŞs do sexo masculino, sĂŁo evidĂŞncias que contribuem para essa hipĂłtese. É importante salientar que esses resultados foram observados em uma população pequena, de origem Ă©tnica definida, contribuindo com apenas uma pequena fração do componente genĂ©tico da herdabilidade da gemelaridade. Mais estudos devem ser realizados em coortes maiores e grupos com diferentes backgrounds genĂ©ticos. No entanto, eles sugerem uma explicação genĂ©tica para o grande aumento na taxa de gemelaridade em CG e tambĂ©m apontam para uma possĂvel nova função dos genes da rota da p53 na reprodução humana.Twinning in humans is a complex etiology event, whose causes are not completely understood. Environmental factors such as advanced maternal age, increased parity, assisted reproduction and hormonal factors, among others, are associated with dizygotic twin pregnancies. Instead, there is little evidence of environmental factors related to monozygotic twins. Despite technological advances in genetics, it is still little knowledge about the genetic factors involved in the etiology of twin pregnancy. There are no clear associations between genetic factors and MZ twin pregnancies. On the other hand, studies show the influence of several genes in DZ twinning and genes that may influence the polyovulation, implantation and embryo development are good candidates for genetic studies. Cândido GodĂłi (CG), located in northwestern of Rio Grande do Sul, is known as the "Twins’ Town" because of its high incidence of twin births. Recently the theory that the twins are product of experiments of Nazi doctor Josef Mengele gained wide dissemination by the press. However, the history of CG suggests that genetic factors, fueled by a founder effect occurred during the colonization of the municipality, are responsible for the recurrent double births in the city. This study aimed to test the plausibility of the "theory of Nazi doctor" and investigate possible genes related to multiple births in CG. For this, we analyzed the baptisms’ books of Catholic Churches of the city, the family histories and surnames of women in the sample collected for genetic testing. We investigated polymorphisms in genes involved in the mechanism of ovulation (Ser680Arg FSHR gene), in the embryo development (677 C ! T MTHFR gene) and in blastocyst implantation (P72R TP53 gene, rs1563828 in MDM4 gene, SNP309 in MDM2 gene, rs1529916 in USP7 gene and rs929271 in LIF gene, all in p53 pathway) in 42 mothers of twins and 101 women who had only singleton pregnancies, all natural of CG. All polymorphisms were identified by the system TaqMan of allelic discrimination by real-time PCR. Zygosity tests were performed in 41 pairs of twins residing in CG by the Applied Identifilier Bisystems. Epidemiological studies show that twin births in CG are recurrent since the beginning of the twentieth century, specifically in a community of this municipality, called Linha SĂŁo Pedro, which reinforces the idea of a founder effect. There are no association between SNPs on FSHR and MTHFR genes and twinning. Nevertheless P72 allele of TP53 gene and T allele of MDM4 gene are associated with twinning in our study. Studies suggest that these alleles are not just involved with tumor suppression, but would be related to infertility, which is therefore a very interesting result. These alleles result in a less efficient apoptosis, therefore, a hypothesis is that these polymorphisms have an important role in post-implantation period, "allowing" the development of two embryos when the most common outcome would be the elimination of at least one. Studies demonstrating that mice with deficient apoptosis keep a greater percentage of their pregnancies, and that the combination of the P72 allele with wild genotypes of MDM2 and LIF change the probability of survival of male babies are a contributing evidence for this hypothesis. Importantly, these results were observed in a small population of defined ethnic origin, contributing only with a small fraction of the genetic component of heritability of multiple births. Further studies should be conducted in larger cohorts and groups with different genetic backgrounds. However, our results suggest a genetic explanation for the increased twinning rate in CG and also point to a possible new function of the route of the p53 gene in human reproduction