Tumors of the soft tissues are classified histogenetically according to their phenotypic resemblance to normal adult tissue, Here we describe molecular approaches that make it possible to distinguish between one class of these tumors, rhabdomyosarcoma, and other small-, round-cell tumors. W e show that the ascertainment of specific genotypic changes can be used to distinguish further between the embryonal and alveolar subtypes of rhabdomyosarcoma. W e tested our model in two ways: first, in a retrospective analysis of diagnostically problematic cases of undifferentiated, small-cell tumors and, second, in a blind study of pediatric tumors. Rhabdomyosarcoma was correctly identified in all cases using this strategy alone. The underlying simplicity of the strategy used to define rhabdomyosarcoma subtypes with molecular markers suggests a model by which tumors can be unequivocally identified, which may apply equally well to other human solid tumors.

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Schizophrenia is a common complex mental disorder. The lifetime prevalence of this disease is about 1% across different populations. The etiology is still unknown despite decades of intensive study. This report is aimed at studying the relationship between chromosomal fragile sites and the etiology of schizophrenia. Lymphocytes of 72 schizophrenic patients and 66 healthy controls were cultured in M medium, which is deficient in folic acid, and in medium RPMI 1640 with distamycin A. G-banding was carried out on 100 metaphases of each individual. Fragile sites were characterized as specific chromosomal bands that exhibit nonrandom gaps or breaks. Culture in M medium resulted in significant differences in the total number of chromosomal lesions and the total number of cells with chromosomal lesions between patients and controls (P<0.001), while no difference was noted after exposure to distamycin A. In the case of M medium, 17 bands in both patients and controls were recognized as expressing fragile sites nonrandomly using a statistical method based on the relationship of the binomial and F distributions. Further analysis using Fisher's exact test revealed a significant excess of expression of a rare fragile site at 2q11.2 among patients compared with controls (P<0.05). In the case of distamycin A induction, 13 bands were identified as having nonrandom expression of fragile sites using the same statistical method. A significant excess expression of a fragile site at 9q12 was identified among patients compared with controls by applying Fisher's exact test (P<0.001). Thus, our data suggest that chromosomal bands 2q11.2 and 9q12 are interesting regions that may harbor important genes associated with schizophrenia.

Testing the nonrandomness of breakage at a chromosome band is an essential step for identifying a fragile site. In this paper, we propose a method derived by using the relationship between the binomial and F distributions for testing nonrandomness. The method is simple in calculation. It was applied to the detection of fragile sites for Chinese patients with colorectal carcinoma.