Molecular confirmation of twinning in the West Indian Manatee (Trichechus manatus) / Confirmação molecular de gemelaridade em peixes-boi marinho (Trichechus manatus)

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.

Twins from different fathers: A heteropaternal superfecundation case report in Colombia / Gemelos de diferentes padres: un caso de superfecundación heteropaternal en Colombia

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.

Live born monochorionic dizygotic twins after in vitro fertilization: a case report / 中华围产医学杂志

This paper reported a pair of twin babies who were diagnosed as monochorionic (MC) twins (MC) in the first-trimester ultrasound scan after in vitro fertilization.Fluorescence in situ hybridization and chromosomal karyotype analysis of amniotic fluid that was randomly collected from one of the twins were performed in the second trimester,but no abnormality was detected.Chromosome karyotype analysis of peripheral blood of the twins at the age of two days and three years showed that both were chi 47,XY,+21/46,XX.And the single nucleotide polymorphism microarray analysis of oral mucosa cells of the twins at three years old showed that the boy was 47,XY,+21 and the girl was 46,XX.Therefore,we confirmed that they are MC dizygotic twins presenting with blood chimerism but no tissue chimerism.Simply the boy presented with facial features of Down syndrome.

Discordant clinical outcomes of congenital Zika virus infection in twin pregnancies / Evolução clínica discordante da infecção congénita do vírus Zika em gestação gemelar

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.

Enfoque de las gestaciones múltiples de diagnóstico difícil durante la autopsia perinatal / Approach to Perinatal Autopsies in Multiple Gestations with Difficult Diagnoses / Enfoque das gestações múltiplas de diagnóstico difícil durante a autopsia perinatal

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.

Aspectos genéticos en el embarazo múltiple

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.

Poland Syndrome in One Dizygotic Twin: A Case Report / 대한주산의학회잡지

Poland syndrome, also known as pectoral aplasia-dysdactylia syndrome, is a rare anomaly, characterized by aplasia of the pectoralis major muscle with ipsilateral upper extremity anomalies. The cause of Poland syndrome is still unknown. Several twin patients were reported to propose a genetic or nongenetic hypothesis. We experienced a female baby showing absence of the pectoralis major muscle in a pair of mixed twin. The patient was referred to our hospital for evaluation of an asymmetric chest wall. She showed depression of the left chest wall, ipsilateral nipple hypoplasia, and axillary webbing. A chest CT scan showed aplasia of the left large pectoral muscle. Our patient had no abnormalities such as symbrachydactyly in an ipsilateral upper extremity. In comparison, a physical examination showed that the fraternal twin boy was completely normal.

Glaucoma crónico de ángulo estrecho en gemelas dicigóticas / Chronic narrow-angle glaucoma found in dizygotic twins

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

Congenital Chloride Diarrhea in Dizygotic Twins / 대한소아소화기영양학회지

Congenital chloride diarrhea (CLD) is a rare inherited autosomal recessive disorder. Mutations of the solute carrier family 26 member 3 gene cause profuse, chloride ion rich diarrhea, which results in hypochloremia, hyponatremia and metabolic alkalosis with dehydration. If a fetal ultrasound shows bowel dilatation suggestive of bowel obstruction, or if a neonate shows persistent diarrhea and metabolic alkalosis, CLD should be considered in the differential diagnosis. The severity of CLD varies, but early detection and early therapy can prevent complications including growth failure. We report a case of dizygotic twins affected by CLD who had been born to non-consanguineous parents. Both of them showed growth failure, but one of the twins experienced worse clinical course. He showed developmental delay, along with dehydration and severe electrolyte imbalance. He was diagnosed with CLD first at 6-month age, and then the other one was also diagnosed with CLD.

Fetal discrepancy during first trimester in dichorionic twins / 中华超声影像学杂志

Objective To investigate the incidence and distribution of fetal discrepancy during the first trimester in dichorionic twins.Methods This was a prospective analysis of dichorionic twin pregnancies that underwent 11+0～ 13+6 week scan at a tertiary hospital from Sep 2008 to Oct 2010.Differences in crown-rump length (CRL),nuchal translucency ( NT),heart rate ( HR).deepest vertical pockets of amniotic fluid (DVP) for every pair of twin fetuses were calculated and expressed as absolute value and percentage of discordance.Results A total of 66 dichorionic twin pregnancies were included.The average CRL was significantly different between the larger fetus and the smaller one,which were (65.28 ±8.54)mm and (62.34 ± 8.49) mm respectively ( P ＜ 0.001).The average NT was significantly different between two fetuses,which were ( 1.56 ± 0.35) mm and (1.28 ± 0.30) mm respectively. HR and DVP were also statistically different between two fetuses ( P ＜0.001).Conclusions The growth of two fetuses in normal dichorionic twins is not uniform during the first trimester.

A Case Report on 30-Week Premature Twin Babies with Congenital Myotonic Dystrophy Conceived by In Vitro Fertilization

Congenital myotonic dystrophy type 1 (DM1) presents severe generalized weakness, hypotonia, and respiratory compromise after delivery with high mortality and poor prognosis. We presented a congenital DM1 of premature twins in the 30th week of gestation. These twins were conceived by in vitro fertilization (IVF). Both babies presented apnea and hypotonia and had characteristic facial appearance. They were diagnosed DM1 by genetic method. They were complicated by chylothorax and expired at 100 and 215 days of age, respectively. Mother was diagnosed DM1 during the evaluation of babies. This is the first report on congenital DM1 which accompanied the chylothorax. More investigation on the association with chylothorax and congenital DM1 is recommended. With a case of severe neonatal hypotonia, congenital DM1 should be differentiated in any gestational age. Finally, since DM1 is a cause of infertility, we should consider DM1 in infertility clinic with detailed history and physical examination.

Blood Chimerism in a Dizygotic Dichorionic Pregnancy / 대한진단검사의학회지

Blood chimerism in twins is known to occur through the transfer of hematopoietic stem cells between the fetuses via a common placenta. We present a case of blood chimerism in a dizygotic dichorionic twin pregnancy. The female twin was delivered at 34 weeks of gestation, and the male twin was stillborn. Pathologic examination confirmed dichorionic diamniotic placentas. The karyotype of the female child was obtained using peripheral blood sample, and it revealed a mixture of 46,XX and 46,XY cells (chi 46,XY[13]/46,XX[7]). FISH analysis performed on the buccal cells by using CEP X/Y probe (Abbott Molecular Inc., USA) revealed 100% XX signals (nuc ish Xcen(DXZ1x2)[500]). Gross examination of the external genitalia and abdominal ultrasonography revealed no definitive abnormal findings in relation to sex differentiation. When XX/XY chimerism is present in blood lymphocytes, careful examination of external genitalia and reproductive organs and further studies are required to detect chimerism in non-hematopoetic tissues. This is a rare case of blood chimerism in dichorionic placentas, in contrast to those in monochorionic placentas.

Percepção estética das manchas de fluorose dentária: relato de caso de gêmeas dizigóticas / Aesthetic perception of dental fluorosis: a case report of dizygotic twins

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.

A case of down's syndrome in twins of unlike sex / 대한주산의학회잡지

Down syndrome is a chromosome related desease that shows mental retardation, growth retardation and many other signs such as defects in the face, hands and skin. Down syndrome is very uncommon in dizygotic twins, especially in twins with different sex. This twin's chromosomal analysis shows both twins with trisomy 21, but the parents' chromosomal analysis is normal. A 30 year old infertile woman who became pregnant via ICSI(intracytoplasmic sperm injection) has shown dizygotic twins with different sex to have Down syndrome and therefore it is being reported along with simple documents.

Genetic and Environmental Influences on Birthweight in a Sample of Korean Twins

This study is the first report of genetic and environmental influences on birthweight using Korean twins. The sample consisted of 255 monozygotic (MZ) and 178 dizygotic (DZ) twin pairs drawn from the Seoul Twin Family Study. Intraclass twin correlations were computed for the twins' birthweights obtained from parents (typically mothers) of the twins. To estimate genetic and shared and nonshared environmental influences on birthweight, standard univariate model-fitting analyses were performed using a software, Mx. For each gender, MZ twin correlations were higher than DZ twin correlations, suggesting existence of genetic influences on birthweight; however, DZ twin correlations were higher than half the MZ twin correlations, indicating that shared environmental factors are also important. For each zygosity, twin correlations were not significantly different between males and females, implicating that genes and environments that cause individual differences in birthweight may not vary between males and females. Model-fitting analyses based on the data pooled across gender yielded estimates of 17% for genetic, 60% for shared environmental, and 23% for nonshared environmental influences on birthweight.

Gastrosquisis en gemelos dicigóticos / Gastrochisis in dizygotic twins

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.

Two Cases of Collodion baby in Dizygotic Twins / 대한피부과학회지

We report herein two cases of collodion baby in dizygotic twins, one boy and one girl. The babies were presented with general involvement of enclosement in a constricting parchment-like or collodion-like membrane, followed by its shedding and revealing red skin underneath. Histologically, compact dense hyperkeratosis and mild cellular infilterate in the upper dermis were seen, without parakeratosis or prominent granular layer. The babies markedly improved about 1 month later. The mild ichthyotic skin remained in the lower legs.

Twinning In Selected Coastal Areas Of South Kerala.

A total of 26,237 deliveries were monitored for twinning and malformations at the 4 government hospitals catering to the population of Kollam and Alapuzha-districts of South Kerala. Among these 7.8 per thousand were twin births showing an increase in the incidence with maternal age. The twin births were high among children of consanguineous marriages (11.7 per thousand) as compared to non-consanguineous marriages (7.7 per thousand). Still births and malformations were also higher in twin deliveries as against singleton deliveries. A large data base is being built to establish a twin registry.