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.

The first case of congenital blood chimerism in two of the triplets in Korea.

BACKGROUND: Chimeras are composed of two or more different populations that originated from different zygotes. Blood chimerism arising from twins have been reported in the literature. Herein, we report the first blood group chimerism in triplets. METHODS: ABO blood grouping was carried out by manual tile methods (Merck Millipore, UK) and micro-column agglutination method (Bio-Rad, Cressier sur Morat, Switzerland). Flow cytometric analysis was performed with Anti-A-PE conjugated monoclonal antibodies (BD Biosciences, San Jose, CA, USA) and FACS Canto II (BD Biosciences). Molecular analysis was performed with allele-specific polymerase chain reaction (AS-PCR) and direct sequencing of the exons 6 and 7. RESULTS: Mixed-field agglutination and weak agglutination against anti-A were revealed by ABO blood grouping. Flow cytometric analysis revealed the presence of both A cells and O cells. AS-PCR and sequencing showed two neonates with chimerism, with each neonate`s genotype being A102/O01/O02. CONCLUSION: This is the first recorded case of blood chimera from a triplet in Korea. We recommend full investigation of blood group chimerism in neonates with ABO discrepancy, as blood chimerism is subject to certain caution in the clinical environment.

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

BACKGROUND: Monochorionic twins are generally considered as a monozygotic twin pregnancy. However, several cases of monochorial dizygotic twin pregnancies have been reported. CASE REPORT: 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. RESULTS: 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. CONCLUSION: 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.

An optimized mouse parabiosis protocol for investigation of aging and rejuvenative mechanisms.

Surgical parabiosis enables sharing of the circulating milieu between two organisms. This powerful model presents diverse complications based on age, strain, sex, and other experimental parameters. Here, we provide an optimized parabiosis protocol for the surgical union of two mice internally at the elbow and knee joints with continuous external joining of the skin. This protocol incorporates guidance and solutions to complications that can occur, particularly in aging studies, including non-cohesive pairing, variable anesthesia sensitivity, external and internal dehiscence, dehydration, and weight loss. We also offer a straightforward method for validating postoperative blood chimerism and confirming its time course using flow cytometry. Utilization of our optimized protocol can facilitate reproducible parabiosis experimentation to dynamically explore mechanisms of aging and rejuvenation.

Laser therapy for twin-twin transfusion syndrome in a dizygotic monochorionic twin pregnancy: A case report.

OBJECTIVE: A monochorionic dizygotic (MCDZ) twin is rare, especially when complicated with twin-twin transfusion syndrome (TTTS) and treated by laser therapy. CASE REPORT: A pregnancy achieved from oocyte donation and intracytoplasmic sperm injection resulted in two embryos transferred. A monochorionic diamniotic twin pregnancy was diagnosed by an early ultrasound; however, at 16 weeks of gestation, instead of the same sex, the ultrasound suspected there was sex discrepancy between the twins. TTTS with severe polyhydramnios occurred at 22 weeks, leading to a laser therapy, which was followed with a smooth post-operation course. Then the Cesarean section was performed at the gestational age of 29 weeks due to severe preeclampsia, giving birth to two live newborns: one female and one male baby both without neurological sequelae at the time of discharge. Blood chromosomes obtained at delivery and 65 days after delivery all revealed an XX and XY chimera from both babies. CONCLUSION: Laser therapy is also effective in MCDZ twin complicated with TTTS. Determination of chorionicity in early pregnancy could timely prompt us to watch out for complications unique to monochorionic twin pregnancy.

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.

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.