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Abstract: Few twinning events have been recorded in the West Indian manatee (Trichechus manatus, Sirenia: Trichechidae) and no previous published study has provided confirmation of this phenomenon based in molecular tools. Here we investigate a possible case of twinning in an endangered Brazilian population of T. manatus using molecular tools. We analyzed two male neonates found stranded in Ceará State, on the northeastern coast of Brazil. The DNA of both individuals was isolated, and 10 microsatellite loci were amplified and genotyped. Following the identification of the alleles, the probabilities of identity by descent (∆7 and ∆8) and relatedness (rxy) were calculated using estimators that evaluate inbreeding. The two individuals shared most of the alleles, with differences in the genotypes being identified in only two loci. All the estimators identified a level of relatedness compatible with that found between siblings (selfed or outbred), indicating they were dizygotic twins. This is the first confirmed case of fraternal twins in free-ranging West Indian manatees in South America. The recognition of this type of twinning provides elements to improve actions for the rehabilitation of stranded animals and their subsequent release to the environment.

Resumo: Poucos eventos de gemelaridade foram registrados para o peixe-boi marinho (Trichechus manatus, Sirenia: Trichechidae) e nenhum estudo previamente publicado confirmou esse fenômeno com base em ferramentas moleculares. Aqui investigamos um possível caso de gemelaridade em uma ameaçada população brasileira de T. manatus utilizando ferramentas moleculares. Foram analisados dois neonatos machos encontrados encalhados no Ceará, costa nordeste do Brasil. O DNA dos indivíduos foi isolado e 10 loci microsatélites foram amplificados e genotipados. Após a identificação dos alelos, as probabilidades de identidade por descendência (∆7 e ∆8) e relação (rxy) foram calculadas usando estimadores que avaliam endogamia. Os dois indivíduos partilharam a maioria dos alelos, com diferenças nos genótipos sendo identificadas em apenas dois loci. Todos os estimadores identificaram um nível de parentesco compatível com o encontrado entre irmãos (com e sem endogamia), o que aponta para o fato de serem gêmeos dizigóticos. Este é o primeiro caso confirmado de gêmeos fraternais em peixes-boi marinho de vida livre na América do Sul. O reconhecimento deste tipo de gemelaridade fornece elementos para aprimorar ações que visem a reabilitação de animais encalhados e sua posterior soltura ao ambiente.

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Heteropaternal superfecundation is an extremely rare phenomenon that occurs when a second ova released during the same menstrual cycle is additionally fertilized by the sperm cells of a different man in separate sexual intercourse. In August, 2018, the Grupo de Genética de Poblaciones e Identificación at Universidad Nacional de Colombia received a request to establish the paternity of a pair of male twins with genetic markers. The following analyses were performed: amelogenin gene, autosomal short tandem repeat (STR), and Y-STR analyses by means of human identification commercial kits, paternity index, and the probability of paternity calculation and interpretation. A paternity index of 2.5134E+7 and a probability of paternity of 99.9999% for twin 2 were obtained while 14 out of 17 Y-chromosome markers and 14 out of 21 autosomal short tandem repeats were excluded for twin 1. The results indicated that the twins have different biological fathers. Although heteropaternal superfecundation is rarely observed among humans given its low frequency, in paternity disputes for dizygotic twins it is mandatory to demand the presence of the two twins in the testing to avoid wrong conclusions.

La superfecundación heteropaternal es un fenómeno extremadamente raro que se produce cuando un segundo óvulo, liberado durante el mismo ciclo menstrual, es fertilizado por un espermatozoide de un hombre diferente en relaciones sexuales separadas. En agosto de 2018, el Grupo de Genética de Poblaciones e Identificación de la Universidad Nacional de Colombia recibió una solicitud para establecer la paternidad mediante marcadores genéticos de un par de mellizos varones, en quienes se hizo el análisis del gen de amelogenina, el análisis de repeticiones cortas en tándem (Short Tandem Repeats, STR) autosómicas y del cromosoma Y (Y-STR) mediante kits comerciales de identificación humana y cálculos e interpretación del índice de paternidad y probabilidad de paternidad. Se obtuvo un índice de paternidad de 2,5134E+7 y una probabilidad de paternidad de 99,9999 % para el gemelo 2, en tanto que en el gemelo 1 se excluyeron 14 de los 17 marcadores del cromosoma Y y 14 de los 21 sistemas STR autosómicos evaluados. Los resultados indicaron que los gemelos tienen diferentes padres biológicos. A pesar de que la superfecundación heteropaternal rara vez se observa en humanos debido a su baja frecuencia, en las disputas de paternidad para los gemelos dicigóticos, es obligatorio exigir en la prueba la presencia de los dos gemelos para evitar conclusiones incorrectas.

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Abstract: Heteropaternal superfecundation is an extremely rare phenomenon that occurs when a second ova released during the same menstrual cycle is additionally fertilized by the sperm cells of a different man in separate sexual intercourse. In August, 2018, the Grupo de Genética de Poblaciones e Identificación at Universidad Nacional de Colombia received a request to establish the paternity of a pair of male twins with genetic markers. The following analyses were performed: amelogenin gene, autosomal short tandem repeat (STR), and Y-STR analyses by means of human identification commercial kits, paternity index, and the probability of paternity calculation and interpretation. A paternity index of 2.5134E+7 and a probability of paternity of 99.9999% for twin 2 were obtained while 14 out of 17 Y-chromosome markers and 14 out of 21 autosomal short tandem repeats were excluded for twin 1. The results indicated that the twins have different biological fathers. Although heteropaternal superfecundation is rarely observed among humans given its low frequency, in paternity disputes for dizygotic twins it is mandatory to demand the presence of the two twins in the testing to avoid wrong conclusions.

Resumen: La superfecundación heteropaternal es un fenómeno extremadamente raro que se produce cuando un segundo óvulo, liberado durante el mismo ciclo menstrual, es fertilizado por un espermatozoide de un hombre diferente en relaciones sexuales separadas. En agosto de 2018, el Grupo de Genética de Poblaciones e Identificación de la Universidad Nacional de Colombia recibió una solicitud para establecer la paternidad mediante marcadores genéticos de un par de mellizos varones, en quienes se hizo el análisis del gen de amelogenina, el análisis de repeticiones cortas en tándem (Short Tandem Repeats, STR) autosómicas y del cromosoma Y (Y-STR) mediante kits comerciales de identificación humana y cálculos e interpretación del índice de paternidad y probabilidad de paternidad. Se obtuvo un índice de paternidad de 2,5134E+7 y una probabilidad de paternidad de 99,9999 % para el gemelo 2, en tanto que en el gemelo 1 se excluyeron 14 de los 17 marcadores del cromosoma Y y 14 de los 21 sistemas STR autosómicos evaluados. Los resultados indicaron que los gemelos tienen diferentes padres biológicos. A pesar de que la superfecundación heteropaternal rara vez se observa en humanos debido a su baja frecuencia, en las disputas de paternidad para los gemelos dicigóticos, es obligatorio exigir en la prueba la presencia de los dos gemelos para evitar conclusiones incorrectas.

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Twin hematopoietic chimera in humans is a phenomenon that was discovered accidentally and the prevalence of which remains unclear. The resolution of chimera cases requires studying family medical records, data analysis, and investigations of hematopoietic cells and cells from other tissues. The interactions among ABO, Lewis, and secretor histo-blood group systems are explored to resolve cases of hematopoietic chimera. Here we report a rare case of hematopoietic chimera where twins present a mixed field reaction in the ABO, Rh, and Kidd red blood cell phenotyping. Using red blood cells separated from the mixed field as well as molecular approaches and investigations of family members, we identify inconsistent genotypes with the Mendelian inheritance pattern when comparing the peripheral blood with the buccal epithelium of the male twin and his twin sister. Analysis of the ABO, Lewis, and secretor phenotypes, and genomic DNA from buccal epithelium showed the genotypes ABO*A1.01/ABO*B.01 and FUT2*01N.02/ FUT2*01N.02 in the male twin and the genotypes ABO*O.01.01/ABO*O.01.02 and FUT2*01/FUT2*01 in the female twin. The results of the HLA-DRB1 genotyping showed inconsistency between the male and his twin sister. We conclude that the serological analyses combined with molecular approaches used in this study are good tools to resolve cases of hematopoietic chimera.

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ABSTRACT Congenital Zika syndrome is an emergent cause of a congenital infectious disorder, resulting in severe damage to the central nervous system and microcephaly. Despite advances in understanding the pathophysiology of the disease, we still do not know all the mechanisms enrolled in the vertical transmission of the virus. As has already been reported in other types of congenital infectious disorders in dizygotic twin pregnancies, it is possible that the virus affects only one of the fetuses. In this article, we report on two cases of twin pregnancies exposed to the Zika virus, but with only one of the fetuses affected with microcephaly and brain damage. This indicates the urgent need for more studies regarding the pathophysiology of viral infection and the mechanisms involved in the natural protection against the virus.

RESUMO A síndrome congênita do Zika vírus é uma causa de infecção congênita emergente, resultando em graves danos ao sistema nervoso central e microcefalia. Apesar dos avanços na compreensão da fisiopatologia da doença, ainda não conhecemos todo o mecanismo envolvido na transmissão vertical do vírus. Como já foi relatado em outros tipos de infecções congênitas em gestações gemelares dizigóticas, é possível que apenas um dos fetos seja afetado pelo vírus. Este artigo descreve 2 casos de gestações gemelares expostas ao vírus Zika, onde apenas um dos fetos foi afetado, com microcefalia associado a graves danos no sistema nervoso central. Isso indica a necessidade urgente de mais estudos sobre a fisiopatologia da infecção viral e os mecanismo envolvidos na proteção natural contra o vírus.

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Objectives: To determine if the large and highly reproducible interindividual differences in arousal intensity and heart rate response to arousal (ΔHR) during non-REM sleep are heritable. Methods: Polysomnograms of 55 monozygotic (14 male and 41 female pairs) and 36 dizygotic (15 male and 21 female pairs) same-sex twin pairs were analyzed. Arousals were scored using the 2012 American Academy of Sleep Medicine criteria. Arousal intensity was scaled (between 0 and 9) using an automatic algorithm based on the change in electroencephalogram time and frequency characteristics. The ΔHR was determined at each arousal. We calculated average arousal duration, average arousal intensity, average overall ΔHR, average ΔHR at a given arousal intensity, slope of ΔHR per arousal intensity, and arousal intensity threshold of ΔHR. Results: The intraclass correlations among monozygotic and dizygotic twin pairs were 0.663 and 0.146, respectively, for average arousal intensity, and 0.449 and 0, respectively, for arousal intensity threshold of ΔHR controlling for age, sex, and race. These values imply large broad sense heritability (H2) for these traits. This evidence was confirmed by a robust maximum likelihood-based variance components estimation approach, with an additive genetic heritability of 0.64 (95% confidence interval: 0.48 to 0.80) for average arousal intensity and a combined additive and dominance genetic heritability and of 0.46 (0.25 to 0.68) for arousal intensity threshold of ΔHR. Results also suggested significant additive genetic effects for average arousal duration, ΔHR at arousal intensity scale 4 and the overall average ΔHR. Conclusion: Genetic factors explain a significant fraction of the phenotypic variability for average arousal intensity and arousal intensity threshold of ΔHR. Results suggest that the duration of arousals and specific average ΔHR values may also be heritable traits. Clinical trial registration: NCT02827461.

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Resumen Introducción: Durante el examen de pediatría, genética, ecográfico o de anatomía patológica de fetos de gestaciones gemelares, suelen aparecer interrogantes en el diagnóstico diferencial, especialmente cuando los casos se asocian con maceración, malformaciones o duplicación de estructuras. Objetivo: Proponer un algoritmo para el enfoque de la autopsia perinatal en gestaciones múltiples de difícil diagnóstico. Materiales y Métodos: Estudio observacional descriptivo del universo de gestaciones gemelares vistas en el Departamento de Patología del Hospital Universitario San Ignacio (HUSI) entre 2007 y 2013. Definimos como "gestación múltiple de difícil diagnóstico" aquella en la que el examen del (de los) feto(s) planteó uno de los diagnósticos diferenciales: feto macerado/evanescente, gemelo siamés, fetus in fetu, feto acárdico o teratoma congénito. Se realizó el estudio anatomopatológico y junto con la literatura revisada, los gemelos se analizaron y clasificaron según el algoritmo propuesto. Resultados: Hubo 59 casos de gestaciones gemelares en las que al menos uno de los fetos requirió autopsia perinatal. Las principales causas de muerte fueron las infecciones ascendentes seguidas del síndrome de transfusión feto-fetal. Como gestaciones múltiples de difícil diagnóstico observamos tres fetos acárdicos y ocho fetos macerados. Se aplicó el algoritmo propuesto en este artículo. Conclusiones: El diagnóstico en las gestaciones gemelares puede ser en ocasiones difícil. Identificamos los aspectos más importantes a tener en cuenta de la historia clínica y de la autopsia perinatal para llegar al diagnóstico definitivo. Desarrollamos un algoritmo para ser aplicado en estas circunstancias durante las autopsias perinatales.

Abstract Introduction: During pediatric, genetic, sonographic, or pathological anatomy examination on complicated twin gestational fetuses, questions arise concerning differential diagnosis, especially when cases are associated with malformations, maceration of several months duration, or complex structural duplications. Objective: To propose an algorithm for approaching perinatal autopsy in complicated multiple gestations. Materials and Methods: Descriptive observational study on twin gestations seen in the Hospital Universitario San Ignacio (HUSI) in 2007-2013. We defined "complicated twin gestation" as one in which an examination of the fetus or fetuses raised one of the following differential diagnoses: macerated fetus, conjoined fetuses, fetus in fetu, acardiac fetus, or congenital teratoma. An anatomopathological study was performed and twins were classified according to the proposed algorithm. Results: Analysis of 59 cases in which at least one fetus required a perinatal autopsy. The leading causes of death were ascending infections and fetal-twin transfusion syndrome. Among complicated multiple gestations we observed eight fetuses including three acardiac macerated fetuses. We applied the algorithm proposed in this article. Conclusion: Diagnosis in twin pregnancies can sometimes be difficult. We identify the most important aspects of medical records and perinatal autopsy to be considered in reaching a definitive diagnosis; we develop an algorithm to be applied in these circumstances.

Resumo Introdução: Durante o exame de pediatria, genética, ecográfico ou de anatomia patológica de fetos de gestações gemelares, costumam aparecer interrogantes no diagnóstico diferencial, especialmente quando os casos se associam com maceração, com malformações ou com duplicação de estruturas. Objetivo: Propor um algoritmo para o enfoque da autopsia perinatal em gestações múltiplas de difícil diagnóstico. Materiais e Métodos: Estudo observacional descritivo do universo de gestações gemelares vistas no Departamento de Patologia do Hospital Universitário San Ignacio (HUSI) entre 2007 e 2013. Definimos como "gestação múltipla de difícil diagnóstico" aquela na que o exame do(s) feto(s) apresentou um dos diagnósticos diferenciais: feto macerado/evanescente, gêmeo siamês, fetus in fetu, feto acárdico ou teratoma congênito. Realizou-se o estudo anatomopatológico e junto com a literatura revisada, os gêmeos se analisaram e classificaram segundo o algoritmo proposto. Resultados: Houve 59 casos de gestações gemelares nas que pelo menos um dos fetos requereu autopsia perinatal. As principais causas de morte foram as infeções ascendentes seguidas da síndrome de transfusão feto-fetal. Como gestações múltiplas de difícil diagnóstico observamos três fetos acárdicos e oito fetos macerados. Aplicou-se o algoritmo proposto neste artigo. Conclusões: O diagnóstico nas gestações gemelares pode ser em ocasiões difícil. Identificamos os aspectos mais importantes a ter em conta da história clínica e da autopsia perinatal para chegar ao diagnóstico definitivo; desenvolvemos um algoritmo para ser aplicado nestas circunstâncias durante as autopsias perinatais.

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The present study investigates the twinning rates in the city of São Paulo, Brazil, during the years 2003-2014. The data were drawn from the Brazilian Health Department database of Sistema de Informações de Nascidos Vivos de São Paulo-SINASC (Live Births Information System of São Paulo). In general, more information is available on the incidence of twinning in developed countries than in developing ones. A total of 24,589 twin deliveries and 736 multiple deliveries were registered in 140 hospitals of São Paulo out of a total of 2,056,016 deliveries during the studied time period. The overall average rates of singleton, twin, and multiple births per 1,000 maternities (‰) were 987.43, 11.96 (dizygotic (DZ) rate was 7.15 and monozygotic (MZ) 4.42), and 0.36, respectively. We further regressed maternal age and historical time period on percentage of singleton, twin, and multiple birth rates. Our results indicated that maternal age strongly positively predicted twin and multiple birth rates, and negatively predicted singleton birth rates. The historical time period also positively, although weakly, predicted twin birth rates, and had no effect on singleton or multiple birth rates. Further, after applying Weinberg's differential method, we computed regressions separately for the estimated frequencies of DZ and MZ twin rates. DZ twinning was strongly positively predicted by maternal age and, to a smaller degree, by time period, while MZ twinning increased marginally only with higher maternal age. Factors such as increasing body mass index or air pollution can lead to the slight historical increase in DZ twinning rates. Importantly, consistent with previous cross-cultural and historical research, our results support the existence of an age-dependent physiological mechanism that leads to a strong increase in twinning and multiple births, but not singleton births, among mothers of higher age categories. From the ultimate perspective, twinning and multiple births in later age can lead to higher individual reproductive success near the end of the reproductive career of the mother.

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El estudio de la genética de la gemelaridad es un campo en continuo avance. A pesar de la investigación intensa, aún no se conoce qué genes intervienen y dirigen la división de un blastocisto que dará origen a dos individuos idénticos, pero se van develando posibles mecanismos así como las diferencias entre gemelos monocigóticos y dicigóticos.

Genetic study of gemelarity is a learning continuum. Intense research has not yet determined genes intervening and leading to blastocyst division that originate two identical individuals but possible mechanisms are unveiled as well as differences between monozygotic and dizygotic twins.

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Caso clínico: se informa el caso de una pareja de gemelas dicigóticas con diagnóstico de glaucoma crónico de ángulo estrecho en 2004, cuyol padre murió ciego; una hija de una de ellas fue diagnosticada posteriormente como afectada de glaucoma crónico de ángulo abierto. Se determinó la cigosidad de las gemelas mediante protocolo establecido al respecto. En los 4 ojos de las pacientes se determinaron presiones intraoculares por aplanación en cifras que fluctuaban entre 26-32 mmHg, cámaras anteriores y ángulos camerulares estrechos, perimetrías computarizadas tubulares en 3 ojos respetando los 5° centrales y en otro tubular que respetaba los 10° centrales con atrofias ópticas en evolución en los 4 ojos. Se efectuó trabeculectomía bilateral en ambas pacientes y se mantuvo el control de su enfermedad glaucomatosa. Conclusiones: se plantea la necesidad de la búsqueda de otros afectados en un núcleo familiar donde se diagnostiquen pacientes con glaucoma crónico de ángulo estrecho

Clinical case: here is the case of a dizygotic twin pair diagnosed with chronic narrow-angle glaucoma in 2994. Their father had died blind and a daughter of one of them was later diagnosed as a chronic open-angle glaucoma patient. A specific protocol allowed determining the zygocity of the twins. The intraocular pressures in the four eyes of the patients were measured with applanation tonometry and ranged 26-32 mmHg, narrow anterior chambers and camerular angles, computerized tubular perimetries in three eyes around central 5° and another tubular perimetry of central 10°, with developing atrophies in the four eyes. Both patients underwent bilateral trabeculectomy and the control over their glaucoma disease was kept. Conclusions: It is necessary to look for other people affected in a family setting where there exists diagnosis of chronic narrow-angle glaucoma

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Objetivo: O objetivo deste trabalho foi apresentar o caso clínico de duas irmãs gêmeas dizigóticas de 8 anos de idade, com fluorose dentária em graus diferentes, avaliar as fontes de flúor a que elas tiveram acesso e analisar a percepção estética das manchas de fluorose. Descrição do caso: O exame clínico foi feito na residência das pacientes, no período diurno, sob luz artificial, utilizando-se o Índice Thylstrup & Fejerskov (ITF). Foi diagnosticado o grau 2 em uma das irmãs (P(1)) e o grau 4 na outra (P(2)) em incisivos centrais superiores. De acordo com o relato da mãe, P(2) ingeriu mais flúor através da escovação com dentifrícios fluoretados que sua irmã P(1) até os três anos de idade. A mãe das crianças percebeu os dentes classificados com grau 4 como esteticamente mais satisfatórios que os dentes classificados com grau 2. Conclusão: O odontopediatra deve ser capaz de realizar um diagnóstico preciso da fluorose dentária e dominar as técnicas de remoção das manchas. Porém, deve-se considerar a percepção individual dos pacientes quanto à estética, seus anseios e suas expectativas com relação a um possível tratamento.

Purpose: The aim of this study was to present a case report of two 8-year-old female patients, dizygotics twins, with different degrees of dental fluorosis, investigate the fluoride sources they were exposed to, and assess the esthetic perception of dental fluorosis. Case description: Clinical examination was performed at home, during day-time, under artificial light, using the Thylstrup & Fejerskov Index (TFI). One twin presented fluorosis degree 2 (P(1)) and her sister presented degree 4 (P(2)) in the central incisors. Their mother reported that P(2) used to swallow more fluoridated dentifrice during tooth brushing than P(1) under the age of 3 year-old. In relation to the esthetic perception of fluorosis, the mother considered that the teeth with degree 4 were more esthetic than the teeth with degree 2. Conclusion: The pediatric dentist should be able to correctly diagnose dental fluorosis and have knowledge on appropriate treatment techniques. However, it is necessary to consider and respect the patients' perception on esthetics and their own desires.

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Se presenta el caso de un par de gemelos dicigóticos, con uno de los fetos afectados por gastrosquisis, diagnosticado prenatalmente a las 22 semanas de edad gestacional por ultrasonografía. Se ofrecen datos acerca de su diagnóstico prenatal y se establece una posible relación entre la gemelaridad, la ingestión de bebidas alcohólicas durante el embarazo y aparición del defecto.

This paper reports a case of dizigotic, one of them affected by gastrochisis, prenatally diagnosed at 22 weeks of pregnancy by ultrasonography. Data about in prenatal diagnosis are offered and we establish a possible relationship between gemelary, alcohol consumption during pregnancy and the apparition of the defect.