DNA Copy Number Changes in Thyroid Medullary Carcinomas Determined by Comparative Genomic Hybridization

BACKGROUND: A point mutation in the RET proto-oncogene, in medullary thyroid carcinoma (MTC) is well known, but no other genetic causes of MTC have been found. This study was performed to identify the most common DNA copy number changes in MTC by comparative genomic hybridization (CGH). METHODS: Twenty-nine surgically resected MTC specimens were retrospectively selected from patients operated on between 1996 and 2004 at the Asan Medical Center. A review of the clinical data and pathological findings was performed. Congored staining and immunohistochemical stains (calcitonin, chromogranin A and CEA) were processed by tissue microarray. CGH analysis was performed. RESULTS: The Congo-red stain was positive in only 12 cases. The immunohistochemical results were positive in 29 cases for chromogranin A, 26 cases for CEA and 25 cases for calcitonin. DNA copy number changes were found in 23 cases (79.3%). The most frequent change was a gain of 19q (65.5%); less frequent changes were gain of 22 (55.2%), 19p (51.7%), 16p (27.58%), 17q (17.24%), and loss of 4q (27.6%) and 3p (17.24%). CONCLUSIONS: DNA copy number changes of MTC were more common (79.3%) than reported in previous studies. The most frequent changes were gains in 19q, 22 and 19p.

The Identification of Genetic Alteration in Cervical Cancer by Comparative Genomic Hybridization (CGH) / 대한부인종양콜포스코피학회잡지

Until recently, cytogenetic studies failed to identify any landmark chromosomal aberrations associated with cervical carcinomas, Recent comparative genome hybridization(CGH) studies have, however, demonstrated that one of the most consistent chromosomal abnormality that marks the transition of carcinoma in situ (CIS) of the cervix to invasive carcinoma is the gain of specific chromosome 3q sequences. Although HPV infection has been demonstrated to be a most important initiating event in the development of most cervical cancers, other additional genetic events are also required for eventual development or progression of invasive cancer. The genetic alterations in cervical cancer were investigated by CGH method using fh frozen specimens. CGH is based on two-color in situ hybridization where genomic tumor DNA is labeled with fluorochrome (FITC) and a normal reference genome is labeled with fluorochrome (Rhodamine) by nick translation. Following co-hybridization of the deferentially labeled genomes to normal reference metaphase chromosomes, Computer Assisted Image Analyzer interprets multicolor fluorescence. The volumetric change in the dual color is typically detected as gain or loss of the DNA sequences in specific region of chromosome. In this study, the pattern of chromosomal aberrations in cervical cancer was not similar to that reported previously by other authors. Overall chromosomal aberration was observed in 46.2%(12/26 cases). The gain of chromosome 5, 11q, 15q, and 17q was most frequent. In deletion, 1q loss was most frequent. There was some cell to cell variability of CGH results in a same tumor sample. The results await careful interpretation and there are several possible reasons of such difference. First reason is a possibility of racial difference in the pattern of chromosomal alteration necessary for cervical carcinogenesis and second one is a possibility of faulty analysis by either improper standardization of computer software or heterogeneity of specimen due to normal cell contamination. However, from the finding that there was no chromosomal aberration in all myometria used for normal control, threshold of normal fluorescence profile in our CGH seems to be reliable. The genetic studies on cervical cancer by this CGH technique should provide new insights into the molecular pathogenesis of lower genital tract cancer and allow for more logical and targeted approach to the cervical cancer management.

Analysis of Fetal Nucleated Erythrocytes in Maternal Blood by Fluorescence In Situ Hybridization(FISH) / 대한산부인과학회잡지

The isolation of fetal cells from maternal circulation has the potential to allow relativelyself prenatal diagosis for all pregnant women. The present technology, however, has notreached the accuracy required for clinical diagnosis because of maternal cell contaminationSo we published a new method for enrichment of nRBC in a fetal cell isolation(1996).In this study, attempted to FISH analysis of nRBC which was isolated by our ownmethods. We evaluated the efficiency of FISH.As the results, we have successfully used FISH on enriched nRBC.We were able to identified 2 abnormal fetus which were confirmed by conventionalcytogenentic study as Down syndrome(Fig.1) and Klinefeltre syndrome(Fig.2). And thesensitivity and specificity for FISH was 86%(49/57) and 92.3%(36/39), respectively.According to our results, fetal cell analysis by FISH can be reliable used for prenatalaneuploidy diagnosis. However, the problems of enrichment of the fetal cell and FISH probeor condition should be over come before analyze.