Spectral karyotyping of seven prenatally detected marker chromosomes and complex chromosome aberrations / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform spectral karyotyping (SKY), fluorescence in situ hybridization (FISH) and conventional karyotyping on prenatally detected marker chromosomes and complex chromosomal aberrations.</p><p><b>METHODS</b>Five marker chromosomes and 2 complex chromosome aberrations diagnosed by G banding were collected. SKY was performed to verify the composition of marker chromosomes. FISH was used to confirm the diagnosis when necessary. In certain cases, C or N banding technique was employed to verify the composition of chromosomes. Results of ultrasonography and pregnancy outcome were reviewed.</p><p><b>RESULTS</b>Among the 5 marker chromosomes, 2 were large and 3 were medium in size, 4 were de novo and one was inherited from the father. By SKY analysis, 2 marker chromosomes have originated from non-acrocentric chromosomes (4 and 9), whilst the other two have originated from acrocentric chromosomes (21 and 22). The remainder was derived from X chromosome. The SKY results were confirmed by FISH in 3 cases. Four cases have chosen to terminate the pregnancy after genetic counseling. A fetus with inherited paternal marker chromosome was delivered at term, and showed normal development during the first year of life. As for the other 2 cases with complex chromosome aberrations, by SKY examination, one had duplication in chromosome 8 and the other had chromosome rearrangements derived from translocation between chromosomes 2 and 6. In the latter case the fetus was delivered at term but showed developmental retardation at 6 months.</p><p><b>CONCLUSION</b>SKY in combination with FISH can facilitate identification of the origins of marker chromosomes as well as complex chromosomal aberrations. With combined information from ultrasonography, SKY and FISH, effective counseling may be offered to the patients.</p>

Combined use of molecular cytogenetic techniques to detect a small chromosomal translocation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Comprehensive use of molecular cytogenetic techniques for the detection of 1 case of small chromosome translocation.</p><p><b>METHODS</b>Following conventional chromosome preparation, G-banding karyotype analysis, spectral karyotyping (SKY), whole chromosome painting, two-color fluorescence in situ hybridization (FISH) and subtelomeric probe FISH were performed.</p><p><b>RESULTS</b>G-banded karyotype was 46, XX, ?(22q11.3), SKY karyotype analysis was 46, XX, der (4)t(4;6) and found no abnormalities on chromosome 22, staining signal was not found with any abnormalities on chromosome 6. Two-color FISH indicated a chromosomal translocation segment of 22q13.3 to one end of the short arm of chromosome 4. Subtelomeric FISH probe showed the end of the long arm of chromosome 22 and the end of the short arm of chromosome 4 reciprocal translocation. High resolution G-banding and FISH result indicated 46, XX, t(4;22)(p15.3;q13.2).</p><p><b>CONCLUSION</b>The testing of small chromosomal translocation should be combined with clinical information and integrated use of molecular cytogenetic techniques to improve the accuracy of diagnosis of chromosomal diseases.</p>