The present study stemmed from a need for a rapid means of deriving reproducible chromosome measurements. An internal set of standards can serve as the basis for routine, easy, and reliable ...morphometric comparisons. In this study, a total of 100 karyotyped metaphases were analyzed using the Nestler Run-Mate, a computerized curvilinear measuring tool. The null hypothesis tested was that there are no significant differences between chromosomal relative-length values obtained via this previously untested approach and those cited in ISCN (1985). The results indicate that this new method is not only feasible and adequate but has advantage over the conventional approach, which requires the use of a projector and screen to measure chromosomes in unkaryotyped metaphase spreads; further, it is less expensive and easier than using computerized digitizing tablets, a conclusion supported by time-and-effort measurements. Immediately obvious applications include routine use in clinical cytogenetics laboratories, as well as for fractional length estimations in fluorescent in situ hybridization studies performed in research laboratories that do not have access to expensive automated instrumentation.
In vitro cytogenetics has been established as a valid method for evaluating the genotoxic potential of chemical agents. Armstrong et al have described a simple, quantitative approach to in vitro ...cytotoxicity and genotoxicity testing by using Chinese hamster ovary (CHO) cells. This approach can also be sensitive and repeatable in an inter-laboratory setting, a prerequisite for routine testing of compounds suspected of having genotoxic properties. In the present study, cytotoxicity was evaluated by the parameter of mitotic index (MI). Genotoxicity is measured by the chromosome aberration (Abs) assay as described by Armstrong et al using CHO cells. The basic analytic principles proposed were extended to include human lymphocytes. Sister chromatid exchange (SCE) analysis was used to establish an additional endpoint. Mitomycin C (MMC), an established clastogen, was used as the model compound for protocol validation. Dose response curves for MI and Abs in CHO cells were found to be consistent with those reported by Armstrong et al. Results from our extended study on lymphocytes and using SCE analysis were analogous. Our experience is that this standardized approach is indeed sensitive and reliable and can serve as a basis for an inter-laboratory testing program.
Klinefelter syndrome is the first human sex chromosomal abnormality to be reported. The majority of Klinefelter syndrome patients have the XXY karyotype. Approximately 15% of Klinefelter patients, ...however, are mosaics with variable phenotypes. Among the variant Kline felter genotypes are such karyotypes as XY/XXY and XX/XXY. The variation in phenotypes most likely depends on the number of abnormal cells and their location in body tissues. In this paper we report the case of a 42-year-old patient with Klinefelter syndrome and a rare variant mosaic XXY/XX karyotype initially identified by GTG-banding. This was confirmed by fluorescence in situ hybridization (FISH) using a dual-color X/Y probe. The patient presented with erectile dysfunction and few other physical findings. Thus, this case illustrates a rare variant of Klinefelter syndrome with a relatively mild phenotype. It also illustrates the utility of FISH as an adjunct to conventional cytogenetics in assessing the chromosome copy number in each cell line of a mosaic. In our case, FISH also detected the presence of a small population of cells with the XY karyotype not previously detected in the initial 30-cell GTG-banding analysis. Thus, through a combination of GTG-banding and FISH, the patient was determined to be an XXY/XX/XY mosaic. Given that most individuals with Klinefelter syndrome are infertile, and that these individuals may wish to reproduce with the aid of modern reproductive technology, such as testicular fine needle aspiration and intracytoplasmic sperm injection, it is important that accurate estimation of the frequency of abnormal cells be obtained for accurate risk estimation and genetic counseling, as recent studies in patients with mosaic Klinefelter syndrome revealed that germ cells with sex chromosomal abnormalities were nevertheless capable of completing meiosis.
