Chimerism resulting from parthenogenetic activation and dispermic fertilization.
Whole-body human chimerism is the result of two zygotes giving rise to one individual, and is a rarely detected condition. We have studied the molecular background and discuss the likely mechanism for the chimerism in a patient with a 46,XX/47,XY,+14 karyotype and ambiguous genitalia, cryptorchidism, pigment anomalies, and normal psychomotor development. We have used karyotyping, interphase-FISH and array-CGH analysis as well as molecular analysis of polymorphic markers from 48 loci in order to define the origin and percentage of 47,XY,+14 cells in different tissues. Based on the findings of two paternal alleles and the detection of homozygous maternal alleles without evidence of crossing-over, and the fact that four alleles were never detected, our results indicate that the chimerism in our patient is the result of dispermic fertilization of a parthenogenetically activated oocyte. Our report underlines that cytogenetic findings suggesting mosaicism might actually indicate chimerism as an underlying mechanism in patients. It also highlights the difficulties in predicting the clinical outcome in patients with genetic aberrations in mosaic or chimeric form.
Winberg
Johanna
J
Department of Molecular Medicine and Surgery and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
Gustavsson
Peter
P
Lagerstedt-Robinson
Kristina
K
Blennow
Elisabeth
E
Lundin
Johanna
J
Iwarsson
Erik
E
Nordenström
Anna
A
Anderlid
Britt-Marie
BM
Bondeson
Marie-Louise
ML
Nordenskjöld
Agneta
A
Nordgren
Ann
A
D046528:Chimerism; D005260:Female; D005306:Fertilization / Q000235:genetics*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D010312:Parthenogenesis / Q000235:genetics*; D012730:Sex Chromosomes; D014564:Urogenital Abnormalities