Segregation of the marker chromosome der(20) in the sperm of a male with karyotype 46,XY[961/ 47,XY+mar[4].
BACKGROUND
The influence of the marker chromosome on reproductive failure is difficult to assess, especially in the case of low-rate mosaicism. The aim of our work was to examine the meiotic segregation of the marker chromosome der(20) in the sperm of a normal male whose wife had experienced three miscarriages, and therefore to determine whether there occurred a gametogenic tissue-specific mosaicism.


METHODS
The proband was a phenotypically normal 35-year-old man, referred for pre-conceptional counseling after his wife had experienced three miscarriages. Chromosome cytogenetic analysis was performed on peripheral blood lymphocytes using routine protocols. Sperm chromosome complements were obtained after penetration of zona-free hamster oocytes. Dual-color FISH analysis was performed using directly labeled probes identifying X, Y, 9 and 20 chromosomes.


RESULTS
A small marker chromosome der(20) was identified in 4% of the proband's lymphocytes and 8.25% of his sperm, which indicated mosaicism among the gametogenic cells, in which the proportion of cells containing the der(20) marker may reach a minimum of approx. 16%.


CONCLUSIONS
In this case, we addressed a problem whether a revealed marker der(20) was the cause of reproductive failure or just a coincidental finding. In our view, each case of low-rate mosaicism of the marker chromosome should be individually assessed.
Wiland
Ewa
E
Institute of Human Genetics, Polish Academy of Sciences, Poznań, Poland.
Jarmumz
Małgorzata
M
Kurpisz
Maciej
M
D000328:Adult; D020090:Chromosome Segregation; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008214:Lymphocytes / Q000166:cytology; D008297:Male; D008540:Meiosis; D009030:Mosaicism; D013094:Spermatozoa / Q000166:cytology*
D005819:Genetic Markers