[Delineating a supernumerary marker chromosome by combining several cytogenetic and molecular cytogenetic techniques].
OBJECTIVE
To characterize a supernumerary marker chromosome (SMC) by comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH) and traditional cytogenetic techniques, and to explore the clinical application of these techniques in delineating de novo marker chromosomes.


METHODS
A mental retardation patient received chromosome test by ordinary G banding. CGH and FISH techniques were used to analyze the origin of the de novo SMC, and N banding technique and C banding techniques were used to analyze the SMC structure. The phenotypic effects of the SMC were analyzed after the karyotype was determined.


RESULTS
By G banding technique, the patient was showed to have a mosaic karyotype with SMC: mos.47, XX, +mar [31]/48, XX, +2mar[29]. CGH analysis showed a gain of 15q11 --> q14, and the result was confirmed by FISH with chromosome 15 painting probe. The further FISH analysis showed the SMC had two signals with UBE3A probe for detecting Prader-willi syndrome/Angelman syndrome (PWS/AS). N banding and C banding analysis showed the SMC had a double satellite and double centromere, respectively. Combined with the above results, the karyotype of the patient was: mos.47, XX, +der (15) (pter --> q14::q14 --> pter) [31]/48, XX, +2der (15) (pter --> q14::q14 --> pter) [29]. ish der(15)(WCP15+, UBE3A++, PML-).


CONCLUSIONS
CGH is a valuable method to detect imbalanced chromosomal rearrangement. Combined with FISH and the traditional cytogenetic technique, it provides a valuable technique platform for characterizing the structure of the de novo SMC, and a basis for exploring the relation between karyotype and phenotype, prognosis and recurrent risk.
Tan
Yue-qiu
YQ
Institute of Reproduction and Stem Cell Engineering, Central South University, Changsha, Hunan, 410078 P. R. China.
Di
Yu-fen
YF
Song
Yuan-zong
YZ
Cheng
De-hua
DH
Li
Lu-yun
LY
Lu
Guang-xiu
GX
D002869:Chromosome Aberrations; D002871:Chromosome Banding; D055028:Comparative Genomic Hybridization; D020732:Cytogenetic Analysis / Q000379:methods*; D003582:Cytogenetics / Q000379:methods*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics; D007621:Karyotyping