Mosaic or chimera? Revisiting an old hypothesis about the cause of the 46,XX/46,XY hermaphrodite.
OBJECTIVE
A cell lineage in a hermaphrodite infant showing a 46,XX/46,XY karyotype was analyzed to determine the genetic contribution from both parents and identify the underlying mechanism.


METHODS
Genotype analysis was performed by using 57 microsatellite markers, 39 distributed on 9 autosomes and 18 on the X-chromosome. Two X- and Y-specific markers were analyzed to confirm the presence and percentages of cells containing a Y-chromosome.


RESULTS
The proband revealed a single maternal and paternal allele for all of the informative autosomal and X-chromosome markers. Analysis of the X- and Y-specific markers confirmed that approximately 20% of the patient's peripheral blood cells contained the Y chromosome.


CONCLUSIONS
The data suggest that the patient's hermaphroditism was the result of a mosaic embryo and not a chimera. The most likely mechanism involved 2 separate nondisjunction events, resulting in the loss of 47,XXY cells during early embryonic development.
Niu
Dau-Ming
DM
Department of Pediatrics, Veterans General Hospital-Taipei, Institute of Clinical Medicine and Genome Research Center, Taiwan.
Pan
Chin-Chen
CC
Lin
Ching-Yuan
CY
Hwang
BeTau
B
Chung
Ming-yi
MY
D002678:Chimera; D012734:Disorders of Sex Development / Q000235:genetics*; D005306:Fertilization / Q000235:genetics*; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018895:Microsatellite Repeats; D009030:Mosaicism