Detection of structural abnormalities in spermatozoa of a translocation carrier t(3;11)(q27.3;q24.3) by triple FISH

Abstract

Structural chromosome abnormalities in spermatozoa represent an important category of paternally transmittable genetic damage. A couple was referred to our centre because of repetitive abortions and the man was found to be a carrier of a reciprocal translocation t(3;11)(q27.3;q24.3). A tailored fluorescence in situ hybridisation (FISH) approach was developed to study the meiotic segregation patterns in spermatozoa from this translocation carrier. A combination of three DNA probes was used, a centromeric probe for chromosome 11, a cosmid probe for chromosome 11q and a YAC probe for chromosome 3q. The frequency of spermatozoa carrying an abnormal chromosome constitution was compared with baseline frequencies in control semen specimens and it was found that a significantly higher percentage of spermatozoa carried an abnormal constitution for the chromosomes involved in the translocation. A normal or balanced chromosome constitution was found in 44.3% of the analysed spermatozoa, while the remainder exhibited an abnormal chromosome constitution reflecting different modes of segregation (15.9% adjacent I segregation, 6.5% adjacent II segregation, 28.9% 3:1 segregation, 0.8% 4:0 segregation, 3.6% aberrant segregation). The frequency of aneuploidy for chromosomes X, Y, 13 and 21 was assessed using specific probes but there was no evidence of interchromosomal effects or variations in the sex ratio in spermatozoa from the translocation carrier. In conclusion, structural aberrations can be reliably assessed in interphase spermatozoa using unique DNA probe cocktails, and this method provides insight into the genetic constitution of germ cells and enables evaluation of potential risks for the offspring.

Fluorescence in situ hybridisation (FISH) analysis of chromosome segregation and interchromosomal effect in spermatozoa of a reciprocal translocation t(9,10)(q11;p11.1) carrier

“…This was not observed in our patient, where the frequency of adjacent-2 segregation occurred at a frequency of only 9.38%. The same data were reported in four published reciprocal translocations t(3;11)(q27.3;q24.3) (Martini et al 1998), t(11;22)(q23;q11) (Estop et al 1997), t(11;22)(q25;q12) (Van Assche et al 1999) and t(17;22)(q11;q12) (Geneix et al 2002).…”

“…Dual-colour FISH with centromeric probes enabled the authors to differentiate between alternate and adjacent-1 segregation because one of the breakpoints had a centromeric position. In our study, as in other published data (Cifuentes et al 1999;Van Hummelen et al 1997;Estop et al 1998;Blanco et al 1998Martini et al 1998Geneix et al 2002), a three-colour FISH analysis using a locusspecific probe for the translocated fragment and centromeric probes has enabled the detection of all types of segregations. The differentiation of adjacent-1 and alternate segregation was also possible because the interstitial segment at meiosis 1 is short, reducing considerably the probability of an interstitial chiasma (Armstrong and Hulten 1998).…”

Recombinant balanced and unbalanced translocations as a consequence of a balanced complex chromosomal rearrangement involving eight breakpoints in four chromosomes

“…Different elegant studies using two, three and four colour FISH have been undertaken for inversions and reciprocal translocations. 19 Multicolour FISH or Spectral Karyotyping (SKY™) approaches with locus specific probes will help to study more complicated translocations and to elucidate meiotic behaviour in such cases. This should be helpful in leading to a better understanding of the mechanisms during meiosis and the assessment of the reproductive risk associated with complex chromosomal translocations.…”

Meiotic segregation analysis in a t(4;8) carrier: comparison of FISH methods on sperm chromosome metaphases and interphase sperm nuclei

“…18,22 According to the hypothesis of Jalbert et al, 23 the following factors seem to favour a 3 : 1 over a 2 : 2 segregation: the translocated segments are very unequal in size, acrocentric chromosomes participate in the reorganisation, and at least one break is near the centromere; thus, the pachytene configuration is highly asymmetrical. In our study, the chromosome segments implicated in the reorganisation produce an asymmetrical quadrivalent (Figure 1).…”

“…The excess of 3 : 1 hypohaploidies over 3 : 1 hyperhaploidies has also been observed in other twocolour FISH 26 and three-colour FISH studies. 28 Other works 22,29 indicated that technical artefacts could explain these apparent discrepancies: the sperm head is small, and as a result the number of probes that can be individually scored is limited. Even with just two probes, the possibility of superimposition of signals has to be considered.…”