Jumping translocation in a phenotypically normal male: A study of mosaicism in spermatozoa, lymphocytes, and fibroblasts.
Both Robertsonian translocations, rob(13;13) and rob(13;15), (in the present case defined as dic(13;15)), are rare chromosomal rearrangements and there is scarce information regarding their behavior during meiosis. In this report we describe a man with mosaicism for two cell lines, each cell line containing a different de novo Robertsonian translocation with the common breakpoint in the centromeric region on chromosome 13. The karyotype was finally defined as: 45,XY,rob(13;13)(q10;q10)[29]/45,XY,dic(13;15)(p11.2;p12)[22], a phenomenon referred to as jumping translocation. The relative occurrence of the two clones in lymphocytes and fibroblasts as well as the meiotic segregation in spermatozoa and the mechanism of formation were studied using karyotype analysis, fluorescence in situ hybridization (FISH), and quantitative fluorescence-PCR. Karyotype analysis of cultured lymphocytes revealed 57% rob(13;13) cells and 43% dic(13;15) cells and for cultured skin fibroblasts the figures were almost identical (56% and 44%, respectively). FISH analysis showed 55% balanced nuclei for unselected spermatozoa and after swim-up selection the number of balanced spermatozoa decreased to 41%. In addition, 16% of the unselected spermatozoa and 27% of the spermatozoa after swim-up selection carried an additional chromosome 13, indicating a high risk for a trisomy 13 offspring. Swim-up selection did not increase the number of balanced spermatozoa.
Iwarsson
Erik
E
Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. erik.iwarsson@ki.se
Sahlén
Sigrid
S
Nordgren
Ann
A
D002467:Cell Nucleus / Q000378:metabolism; D002882:Chromosomes, Human, Pair 13 / Q000235:genetics*; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D004247:DNA / Q000032:analysis / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008540:Meiosis; D009030:Mosaicism; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013094:Spermatozoa / Q000378:metabolism*; D014178:Translocation, Genetic; D055815:Young Adult
D004247:DNA