Monozygotic twins with discordant karyotypes following preimplantation genetic screening and single embryo transfer: case report.
OBJECTIVE
to report a case of monozygotic monochorial diamniotic twins with discordant karyotypes.


RESULTS
the pregnancy was achieved following a treatment cycle with intracytoplasmic sperm injection (ICSI) and preimplantation genetic screening (PGS) for chromosomes X, Y, 13, 16, 18, 21, 22. One embryo euploid for studied chromosomes was transferred. Prenatal ultrasonography revealed monozygotic twins. One fetus had growth retardation, multiple organ abnormalities and polyhydramnion. The other twin had normal ultrasound appearance. Delivery on week 29 of gestation resulted in the birth of two females, a stillborn twin with karyotype 45,XX,-13[12]/46,XX,r(13)[3] and a healthy twin with normal karyotype.


CONCLUSIONS
the discordance in the twins' karyotypes originated from a mosaic embryo. Structural chromosomal abnormality of the affected twin could not be revealed using standard PGS investigation. Embryo splitting occurred probably due to apoptotic process in an early stage of embryo development. Apoptosis represents one of the possible mechanisms which can explain the embryo twinning process globally.
Tauwinklova
Gabriela
G
REPROMEDA s.r.o., Brno, Czech Republic. gtauwinklova@repromeda.cz
Gaillyova
Renata
R
Travnik
Pavel
P
Oracova
Eva
E
Vesela
Katerina
K
Hromadova
Lenka
L
Vesely
Jan
J
Musilova
Petra
P
Rubes
Jiri
J
Kadlecova
Jitka
J
Slamova
Iva
I
Makaturova
Eva
E
Vranova
Vladimira
V
D000328:Adult; D002869:Chromosome Aberrations; D002882:Chromosomes, Human, Pair 13; D005260:Female; D006801:Humans; D009030:Mosaicism; D011247:Pregnancy; D019836:Preimplantation Diagnosis; D056826:Single Embryo Transfer; D020554:Sperm Injections, Intracytoplasmic; D014430:Twins, Monozygotic / Q000235:genetics*