Analysis of chromosomal equipment in spermatozoa of a 46,XY/47,XY/+8 male by means of multicolour fluorescent in situ hybridization: confirmation of a mosaicism and evaluation of risk for offspring.
Trisomy 8 is generally associated with chromosomal mosaicism and occurs de novo, with relatively well-defined clinical manifestations, ranging from minimal effects to severe malformations. Mosaicism is often difficult to ascertain and the confirmation of diagnosis requires several chromosomal investigations on a variety of tissues. We present a case of mosaic trisomy 8 fortuitously found in a healthy 30-year-old man during a cytogenetic investigation for several spontaneous abortions: 8% of the lymphocyte metaphases showed a 47,XY,+8 karyotype. Fluorescent in situ hybridization (FISH) with the probes pJM.128 and L1.84 was performed on decondensed interphase spermatozoa. Of the 25000 analysed cells, 398 spermatozoa (1.59%) exhibited a hybridization pattern compatible with a chromosome 8 disomy; the frequency was higher than in either sperm control populations (0.17% and 0.21%). This result is in agreement with the existence of trisomy 8 mosaicism in the gonads and germ cells. FISH on decondensed interphase spermatozoa spreads is thus an easy non-invasive procedure that can be used to complement mosaicism diagnosis in tissue other than blood. Moreover, FISH provides interesting data for characterizing the risk for offspring.
Mercier
S
S
Laboratoire Histologie-Embryologie-Cytogénétique, IETG Besançon et URA CNRS 0561, Faculté de Médecine, Besançon, France.
Bresson
J L
JL
D000022:Abortion, Spontaneous; D000328:Adult; D002871:Chromosome Banding; D002874:Chromosome Mapping; D002898:Chromosomes, Human, Pair 8; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008214:Lymphocytes; D008297:Male; D009030:Mosaicism; D011247:Pregnancy; D013094:Spermatozoa; D014314:Trisomy