Monochorionic Dizygotic Twins Research Articles

THANATOPHORIC DYSPLASIA: LITERATURE REVIEW AND CLINICAL CASE IN MONOCHORIC DIAMNIOTIC TWINS

Thanatophoric dysplasia, TD (OMIM: 187600, 87601) belongs to the group of FGFR3 chondrodysplasias and is divided intotypes I and II. The incidence of TD is approximately 1:20,000-50,000 newborns. TD is usually caused by pathogenic variantsin the FGFR3 gene, which provides instructions for making a protein involved in the development and maintenance of bone andbrain tissue. Mutations in the gene result in excessive protein activity. TD is inherited as an autosomal dominant trait, althoughcases of autosomal recessive inheritance have been described.According to the radiologic changes of the bones and skull, there are 2 clinical types of TD: type I (TD1, MIM 187600) andtype II (TD2, MIM 187601) with some overlap between them. Type I TD is characterized by micromelia with curved femurs,marked platyspondylia with or without a cloverleaf skull. TD type II is characterized by micromelia with straight femurs andthe uniform presence of moderate to severe craniosynostosis with a leaf-shaped skull deformity due to premature closure of the coronal and lambdoid sutures..The diagnosis of TD is made syndromologically and/or radiologically and/or by detection of a heterozygous pathogenicFGFR3 variant identifi ed by molecular genetic testing.The article presents a rare clinical case of TD in monochorionic dizygotic twins with a fatal outcome. During prenatalultrasound examination at 26-27 and 35-36 weeks of gestation, signs of skeletal dysplasia were diagnosed in both fetuses against the background of pronounced polyhydramnios. It should be noted that the father of the children is over 60 years old.The diagnosis of both children was made syndromologically and radiologically based on the detection of phenotypic signs of TD(predominance of the skull over the face, short upper and lower limbs, altered shape of the chest, infl amed nasal bridge) and radiological signs of TD (short ribs, narrow chest, relative macrocephaly, micromelia of all limbs). Genetic testing for TD was not performed.The clinical case was published with the consent of the parents in accordance with the principles of bioethics.

Rare spontaneous monochorionic dizygotic twins: a case report and a systematic review

BackgroundMonochorionic dizygotic twins are a rare condition, mostly related to assisted reproductive technology. This type of twinning is burdened by the same risk of pregnancy complications found in monochorionic monozygotic pregnancies.Case presentationWe report a case of spontaneous monochorionic dizygotic twins sharing situs inversus abdominalis and isolated levocardia, with only one twin affected by biliary atresia with splenic malformation syndrome. We also conducted a literature review of the 14 available documented monochorionic dizygotic twin gestations spontaneously conceived.ConclusionsIt is still unclear how this unusual type of twinning can occur in spontaneous conception. The evidence so far suggest the importance to timely diagnose the chorionicity, in order to adequately manage the typical complications associated with monochorionicity.

Monochorionic Dizygotic Twins Conceived Spontaneously Showed Chimerism in Karyotype and Blood Group Type.

We report a very rare case of monochorionic dizygotic twins conceived spontaneously. The fetuses were sex-discordant in ultrasonography despite being monochorionic twins. After birth, the girl and boy showed normal phenotypes but they showed blood chimerism in karyotype and blood group type.

Chimerism involving a RB1 pathogenic variant in monochorionic dizygotic twins with twin–twin transfusion syndrome

We report the first case of blood chimerism involving a pathogenic RB1 variant in naturally conceived monochorionic-dizygotic twins (MC/DZ) with the twin-twin-transfusion syndrome (TTTS), presumably caused by the exchange of stem-cells. Twin A developed bilateral retinoblastoma at 7 months of age. Initial genetic testing identified a de novo RB1 pathogenic variant, with a 20% allelic ratio in both twins' blood. Subsequent genotyping of blood and skin confirmed dizygosity, with the affected twin harboring the RB1 pathogenic variant in skin and blood, and the unaffected twin carrying the variant only in blood.

Twin anemia–polycythemia sequence in sex‐discordant monochorionic dizygotic twins

The possibility of monochorionic (MC) dizygotic (DZ) twins was first raised in 1970. As MC sex-discordant twins are rarely observed, MCDZ twins are seldom recognized clinically. Conception by assisted reproductive technology (ART) is associated with an increased frequency of MC diamniotic (DA) twins, with more than 50% of reported MCDZ twins conceived by ART1. With the increased use of ART, it is therefore reasonable to expect that the incidence of MCDZ twins may increase. MC twins share a single placenta and are connected by the placental circulation. They are at risk of transfusion imbalance in this circulation, which may lead to twin–twin transfusion syndrome (TTTS) or twin anemia–polycythemia sequence (TAPS). The diagnosis of TTTS at an early stage is based on discordant amniotic fluid volume. Currently, the diagnosis of TAPS is based on increased middle cerebral artery peak systolic velocity (MCA-PSV) in the donor twin (> 1.5 MoM) and decreased MCA-PSV in the recipient twin (< 1 MoM)2. Postnatally, TAPS can be diagnosed based on an intertwin hemoglobin difference of > 8 g/dL and at least one of the following criteria: (1) reticulocyte count ratio > 1.7; and (2) presence of only small vascular anastomoses on placental examination3. We report a case of TAPS diagnosed prenatally in a MCDZ twin pregnancy. A 32-year-old woman with a spontaneously conceived pregnancy was diagnosed with a MCDA twin gestation at 14 weeks by ultrasound. Sex discordance was noted on the fetal anatomy survey and was suggested on cell-free fetal DNA screening. Sex discordance was confirmed postnatally. A diagnosis of TAPS was suspected at 28 + 6 weeks based on MCA-PSV (1.65 MoM in the donor and 0.48 MoM in the recipient), and worsening of TAPS, with a new finding of placental echogenicity discordance between the donor and recipient sides, was suspected at 30 + 6 weeks (Figure 1). The patient was delivered at 31 + 2 weeks, following administration of corticosteroids and magnesium sulfate for neuroprotection, due to worsening of TAPS. TAPS was confirmed postnatally. Hemoglobin was 25.2 g/dL in the recipient twin and 7.5 g/dL in the donor twin. Reticulocyte count ratio (donor/recipient twin) was 14.7. Monochorionicity was confirmed by pathological examination. In TAPS, the placenta may have a discordant ultrasound appearance (hyperechoic on the donor twin side and hypoechoic on the recipient twin side) and a color difference on gross examination (pale appearance on the donor twin side and dark purple appearance on the recipient twin side)4. The current case demonstrated these findings (Figures 1 and 2). Although a case of TAPS in MCDZ twins was reported recently in a spontaneously delivered pregnancy in which the diagnosis was made postnatally5, we report what we believe to be the first case of TAPS in MCDZ twins that was diagnosed prenatally. Our report demonstrates that discordant MCA-PSV measurements and placental echogenicity differences in MC twin pregnancy are objective ultrasound findings that may indicate a developing and worsening status of TAPS in MCDZ twins. It is important to recognize that MCDZ twin gestations exist. Early determination of chorionicity during the first trimester with confirmation of fetal sex in the second trimester is the key in identifying a MCDZ twin gestation.

A case of blood chimerism and twin-to-twin transfusion syndrome in monochorionic dizygotic twins

A case of blood chimerism and twin-to-twin transfusion syndrome in monochorionic dizygotic twins

Non-confined long-standing blood chimerism in a spontaneous monochorionic dizygotic twin pregnancy.

The present study highlights a rare case of monochorionic dizygotic twins with non‐confined blood chimerism presenting excellent outcome after two‐year follow‐up.

Live born monochorionic dizygotic twins after in vitro fertilization: a case report

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. Key words: Twins, dizygotic; Fertilization in vitro; In situ hybridization, fluorescence; Karyotyping; Polymorphism, single nucleotide

Unusual twinning: Additional findings during prenatal diagnosis of twin zygosity by single nucleotide polymorphism (SNP) array.

To evaluate the incidence and characteristics of unusual twinning by using single nucleotide polymorphism (SNP) array to identify twin zygosity. This study reviewed 386 twin pairs who were seen for prenatal or postnatal diagnosis and underwent SNP array to detect zygosity. The incidence of monozygotic (MZ) twins was 11.36% (25/220) in the assisted reproductive technology (ART)-conceived group. Monochorionic dizygotic twins represented 3 of 24 monochorionic ART-conceived twin pairs (3/24, 12.50%) but none in the spontaneous twin pairs. Among 4 single-embryo transfer twin pairs, 3 represented unusual twinning, including 2 MZ twin pairs with discordant karyotypes and 1 dizygotic twin pair of the same gender. Of the pregnancies with 2 or more embryos transferred, 7.77% (15/193) were MZ. Additionally, there was a dichorionic monozygotic twin pair with placental vascular anastomoses from a day-5 blastocyst transfer. Single nucleotide polymorphism array can provide zygosity diagnosis in addition to chromosomal copy number variation and uniparental disomy detection. ART twin pregnancies have a risk of unusual twinning, such as monochorionic dizygotic, single-embryo transfer twin pairs with discordant karyotypes or dizygotic, and dichorionic monozygotic with vascular anastomoses from day-5 transfer.

OP25.06: Selective feticide in monochorionic dizygotic twins discordant for heart anomaly and sIUGR with prenatally confirmed blood chimerism

OP25.06: Selective feticide in monochorionic dizygotic twins discordant for heart anomaly and sIUGR with prenatally confirmed blood chimerism

Unusual Twinning Resulting in Chimerism: A Systematic Review on Monochorionic Dizygotic Twins

Traditionally, it is understood that dizygotic (DZ) twins always have a dichorionic placenta. However, with 8% blood chimerism in DZ twins, placental sharing is probably more common than previously has been recognized. In this article, we will review all available cases of monochorionic dizygotic (MCDZ) twins. A total of 31 twins have been described in literature. A monochorionic diamniotic placenta is reported in all cases. Assisted reproductive technology is responsible for the origin of the pregnancy in 82.1% of the cases. In 15.4% of the sex-discordant twins, a genital anomaly was reported in one of the twins. Chimerism is demonstrable in 90.3% of the twins, leading to various diagnostic difficulties. As this review shows that most MCDZ twins are discovered by accident, it can be argued that it is far more common than has been assumed until now. However, the prevalence is still unclear. Awareness of MCDZ twinning is important, with subsequently correct medical strategies. Similarly, the resulting (blood) chimerism is essential to consider in diagnostic procedures, pre- and postnatally. More research on the effect of placental transfusion between sex-discordant twins is required.

Confined blood chimerism in a monochorionic dizygotic sex discordant twin pregnancy conceived after induced ovulation

Monochorionic twins are generally considered as a monozygotic twin pregnancy. However, several cases of monochorial dizygotic twin pregnancies have been reported. We report on a rare case of monochorionic dizygotic twin pregnancy conceived after induced ovulation in a 32-year-old woman. The diagnosis was made on morphological ultrasound examination at 18+4 weeks of gestation, showing two fetuses with discordant sex. The amniocentesis was declined by the patient. The monochorionic status was confirmed after a histopathalogical study of the placenta. At delivery, both a phenotypically normal boy and a phenotypically normal girl without sexual abnormality were observed. This analysis also revealed the presence of vascular anastomoses between both fetal circulations. Postnatal cytogenetic analyses indicated the presence of a chimerism in peripheral blood lymphocytes. This chimerism was not observed in cells obtained from a buccal swab. Molecular determination of zygosity confirmed the existence of the confined peripheral blood chimerism with the presence of four parental alleles. We report on a case of monochorionic dizygotic twin pregnancy. This observation underlies the need to carefully assess twin pregnancies, especially when obtained after assisted reproductive technology.

Potential risk of monochorionic dizygotic twin blastocyst formation associated with early laser zona dissection of group cultured embryos

To document the risk of in vitro monochorionic dizygotic twin formation in the implementation of a program of blastocyst biopsy with preimplantation genetic screening (PGS). Case report. Private infertility laboratory. Prospective PGS patients with intracytoplasmic sperm injection-derived, group-cultured blastocysts over a 3-year period. Group culture in Global medium (Life Global) to optimize blastocyst formation of zygotes produced for blastocyst biopsy for PGS (n ≤ 8 embryos/25 μL droplet), and laser zona dissection (LZD) of all day-3 cleaved embryos to promote pre-expansion trophectodermal extrusion at the blastocyst stage (i.e., premature hatching). Blastocyst formation and quality grading on days 5 and 6 of in vitro culture for the vitrified embryo transfer of single or dual euploid blastocysts. Over 3,000 blastocysts were produced in vitro. On two separate occasions, complete trophectodermal amalgamation was observed between two hatching blastocysts. Vitrified single-euploid blastocyst transfers efficiently implanted and established clinical pregnancies similar to dual-euploid blastocyst transfers, without the risk of twin formation. The amazing occurrence of monochorionic dizygotic twin formation has now been documented in vitro, supporting the theory that assisted reproductive technology may facilitate this rare perinatal condition. Furthermore, we have provided clinical evidence that the transfer of a single-euploid blastocyst can optimize a patient's pregnancy success while reducing potentially undesirable conditions associated with monochorionic twin pregnancies.

Monochorionic dizygotic twins with discordant sex and confined blood chimerism

Monochorionic (MC) pregnancy in humans is usually considered to be associated only with monozygotic twinning. However, several reports have revealed that dizygotic (DZ) twins can also share a chorion during pregnancy. A chimera is defined as an organism that contains different cells derived from two or more distinct zygotes. As artificial reproductive techniques develop, it can be predicted that the occurrence of MC DZ twins will increase, and DNA-fingerprinting methods, such as short tandem repeat (STR) analysis, will be essential for their accurate diagnosis. We report the first Korean case of MC DZ twins with blood chimerism, 46,XX/46,XY, as a consequence of in vitro fertilization/embryo transfer. The clinical phenotypes of the twins' genitalia were complete female and male, respectively. Monochorionicity was confirmed by pathological analysis of the placenta after delivery. The dizygosity and confined blood chimerism of the twins were confirmed by STR analysis using their peripheral lymphocytes and skin fibroblasts. The confined blood chimerism of the twins can be considered similar to the status of the hematopoietic system in patients after allogenic bone marrow transplantation. When MC twins with discordant sex are expected during pregnancy, it is important to consider the possibility of DZ twins showing normal sexual development, especially in twins who were fertilized using artificial reproductive techniques.

Chimerism of Buccal Membrane Cells in a Monochorionic Dizygotic Twin

No monochorionic dizygotic twins (MCDZTs) with cellular chimerism involving cells other than blood cells have been reported in the literature to date. Here we report a probable first case of MCDZTs with buccal cell chimerism. A 32-year-old woman conceived twins by in vitro fertilization by using 2 cryopreserved blastocysts that were transferred into her uterus. An ultrasound scan at 8 weeks' gestation showed signs indicative of monochorionic twins. A healthy boy and a healthy girl were born, showing no sexual ambiguity. Cytogenetic analyses and microsatellite studies demonstrated chimerism in blood cells of both twins. Notably, repeated fluorescence in situ hybridization and microsatellite studies revealed chimerism in buccal cells obtained from 1 of the twins. Although the mechanism through which buccal cell chimerism was generated remains to be elucidated, ectopic differentiation of chimeric hematopoietic cells that migrated to the buccal membrane or the cellular transfer between the 2 embryos at the early stage of development might be responsible for the phenomenon. This hypothesis raises an interesting issue regarding embryonic development and cellular differentiation into organs during fetal development. Given the possibility of cryptic chimerism in various organs including gonadal tissues in MCDZTs, close observation will be required to determine whether complications develop in the course of the patients' growth.

Twins Reunited: Scientific and Personal Perspectives/Twin Research Studies: Multiple Birth Effects on IQ and Body Size; Life Style, Muscles, and Metabolism; Monochorionic Dizygotic Twin with Blood Chimerism; Amniocentesis for Twins/Twins in the Media: Identical Doctors; Freedom Fighter for Twins; Twin Scholarships; Auguste and Jean-Felix Piccard; Twins Born Apart

A reunion of 38-year-old female monozygotic twins took place in Daegu, South Korea, on January 14, 2014. Scientific and personal perspectives on this extraordinary event are provided. A review of timely twin research follows, covering the effects of multiple births on IQ and body size, lifestyle and physical fitness associations, a rare case of a dizygotic twin with blood chimerism and definitional issues surrounding amniocentesis-related loss in multiple birth pregnancies. Interesting and informative mention of twins in the media includes twin doctors, a twin freedom fighter, the availability of college scholarships for twins, a new book about the Piccard family (two of whose members were twins), and co-twins born before and after the new year. A follow-up to a previous mention of identical twin biatheletes is also provided.

Chimerism in monochorionic dizygotic twins: Case study and review

Chimerism occurs when an organism contains cells derived from more than one distinct zygote. We focus on monochorionic dizygotic twin blood chimerism, and particularly twin-twin transfusion syndrome in such pregnancies. For years, researchers have understood chimerism to be a common phenomenon in cattle. Although, this review will not delve deeply into animal chimerism, an understanding of chimerism in the animal world can provide clues regarding health implications for human chimeras. This report serves two purposes: an update and assessment of the twins we reported previously in 2010 [Assaf et al., 2010] and a review on dizygotic monochorionic chimeric twins. First, our updated assessment of the twins shows no identifiable regression of Müllerian sex derivatives in the female, and normal neurodevelopment was documented in both. Our research has suggested several key points; one that blood chimerism persists from fetal life to at least age two years. Second, chimerism in humans is not as rare as previously thought, although it has been studied only recently. Third, assisted reproductive technologies appear to increase the risk of monochorionic dizygotic twin pregnancies.

UMBILICAL CORD TWISTS CAUSING INTRAUTERINE FETAL DEMISE OF A MONOZYGOTIC CO-TWIN

Monozygotic twin gestation is associated with adverse perinatal outcome.Umbilical cord related accidents are more common with monoamniotic twin gestations.Twisting of umbilical cord results into sudden death of a co- twin in multifetal gestation.Cord accidents occur suddenly and unexpectedly.A case of fetal demise of co-twin due to multiple twists at the fetal end of the umbilical cord in 34 weeks of monochorionic dizygotic twin gestation is reported.She underwent elective caesarean section with favorable outcome in surviving twin.

Confined Blood Chimerism in Monochorionic Dizygotic Twins Conceived Spontaneously

Traditionally, monochorionicity has been regarded as synonymous with monozygosity. However, several recent cases of monochorionic dizygotic twins have shown that monochorionic twins can be dizygous. We report a rare case of monochorionic diamnionic, gender-discordant twins who were conceived spontaneously. Initially, a monochorionic placenta was diagnosed by ultrasonography at 8 weeks of gestation and then confirmed by pathology after delivery. The twins had different genders. A comparison of cytogenetic analyses using peripheral blood lymphocytes and skin fibroblasts revealed that chimerism was confined to blood cells. We have experienced two cases of monochorionic dizygotic twins since 2003. These cases suggest that monochorionic dizygotic twins are not as rare as previously thought.

Monochorionic dizygotic twins in a spontaneous pregnancy: a rare case report

Traditionally, monochorionicity in multiple pregnancies is associated with monozygocity. We present a case of a spontaneous, monochorionic dizygotic, sex-discordant twin pregnancy. The diagnosis of monochorionicity was initially done during first-trimester ultrasound evaluation and then confirmed by postnatal placental pathology. Furthermore, both twins were found to have blood chimerism. We also review the literature on dizygotic-monochorionic twins and blood-chimerism. We suggest that further prospective postnatal genetic studies are needed to define the reliability of prenatal diagnosis of identical twins in cases of monochorionicity.