Y chromosome heterochromatin of differing lengths in two cell populations of the same individual.
OBJECTIVE
To present a prenatal diagnosis report on a case where G-banding analysis of fetal metaphase chromosomes showed populations of cells with two different Y chromosomes; one with a short block of heterochromatin (Yqh-) and one with a longer block of heterochromatin (Yqh+).


METHODS
These two populations of the Y chromosome were studied using fluorescent quinacrine banding and fluorescent in situ hybridization (FISH). A chromosome paint corresponding to the euchromatic region of the Y chromosome, and probes corresponding to the SRY, DYZ1, and DYZ3 regions were used for this study.


RESULTS
Both Y chromosomes appeared to be structurally normal by these analyses. Subsequent ultrasound examination at 20 weeks' gestation revealed normal male genitalia. Follow-up with a neonatal blood sample analysis confirmed the above findings.


CONCLUSIONS
This study reports a direct prenatal diagnosis case of two populations of the Y chromosome in the same individual. This apparent mosaicism may be explained by a postzygotic simple deletion or unequal crossover event between sister chromatids in the DYZ region.
Akkari
Yassmine
Y
Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon.
Lawce
Helen
H
Kelson
Stephen
S
Smith
Cheree
C
Davis
Craig
C
Boyd
Luke
L
Magenis
R Ellen
RE
Olson
Susan
S
D000328:Adult; D000649:Amniocentesis; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D041322:Chromosomes, Human, Y; D005260:Female; D005865:Gestational Age; D006570:Heterochromatin / Q000235:genetics* / Q000473:pathology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D008297:Male; D009030:Mosaicism; D011247:Pregnancy; D032681:Spectral Karyotyping
D006570:Heterochromatin