ABSTRACT
In some situations, a decision is best represented by an incompletely analyzed act: conditionally on a given event A, the consequences of the decision on sub-events are perfectly known and uncertainty becomes probabilizable, whereas the plausibility of this event itself remains vague and the decision outcome on the complementary event is imprecisely known. In this framework, we study an axiomatic decision model and prove a representation theorem. Resulting decision criteria aggregate partial evaluations consisting of (i) the conditional expected utility associated with the analyzed part of the decision, and (ii) the best and worst consequences of its non-analyzed part. The representation theorem is consistent with a wide variety of decision criteria, which allows for expressing various degrees of knowledge on () and various types of attitude toward ambiguity and uncertainty. This diversity is taken into account by specific models already existing in the literature. We exploit this fact and propose some particular forms of our model incorporating these models as sub-models and moreover expressing various types of beliefs concerning the relative plausibility of the analyzed and the non-analyzed events ranging from probabilities to complete ignorance that include capacities.
ABSTRACT
OBJECTIVES: Early diagnosis of unbalanced chromosomal abnormalities can be crucial in minimizing the trauma caused by an elective abortion. Chorionic villus sampling (CVS) can be performed from 9 weeks of gestation. However, two major problems are encountered in fetal karyotyping using cultured cells from chorionic villi: the relatively slow growth of these cells in culture, which delays the diagnosis, and the occurrence of maternal cell contamination (MCC). With FISH, a result can be obtained within 24 h, and, as no cell culturing is involved, the problem of MCC is minimized. METHODS: Thirty-two women undergoing CVS between 9 and 12 weeks of gestation were offered FISH analysis in addition to the standard chromosome analysis. RESULTS: FISH was informative in all of the cases tested. Eleven aneuploidies were detected in cases of hygroma or abnormal nuchal translucency and two out of four fetuses from parental translocation were unbalanced. The decision to perform early termination of these chromosomally abnormal pregnancies was based on FISH results and ultrasound abnormalities, without waiting for karyotype results. CONCLUSION: The present study confirms that the association of FISH and CVS allows a rapid and early prenatal diagnosis, and emphasizes that this association is of great benefit in cases of known parental balanced translocation or when hygroma is detected by ultrasonography.
Subject(s)
Chorionic Villi Sampling , Chromosome Aberrations , Gestational Age , In Situ Hybridization, Fluorescence , Prenatal Diagnosis/methods , Aneuploidy , Female , Humans , Karyotyping , Lymphangioma, Cystic/genetics , Neck/diagnostic imaging , Neck/embryology , Pregnancy , Pregnancy Trimester, First , Translocation, Genetic , Ultrasonography, PrenatalABSTRACT
Since the establishment of human karyotype in 1956, human cytogenetic has quickly progressed. The description of the Philadelphia chromosome in 1960 led up to new applications of cytogenetic in the fields of hematology and oncology. The initial techniques allowed only uniform staining of chromosomes, limiting the detection of most structural rearrangements. Many approaches aimed to gain a better knowledge of chromosomal structure, a better understanding of rearrangements, and a better identification of the chromosomes were developed: autoradiography, banding techniques, electronic microscopy. Since 1980, new developments in clinical cytogenetic and molecular biology have occurred. In situ labeling using non-radioactive probes onto chromosomes and nuclei was developed: fluorescence in situ hybridization (Fish) was born. Fish allows detecting many chromosomal abnormalities of number and/or structure. The major limitation of this technique is that its use should be based on known indications for the choice of the probe. Multicolor karyotype (M-Fish or Sky), the most recent development of Fish on metaphase spreads, allows to overcome this limit. As shown here in three examples, M-Fish allows to describe precisely complex rearrangements in hematological malignancies and solid tumors. Finally, if no metaphase is available, comparative genomic hybridization (CGH) can be performed to detect and simultaneously localize on chromosomes gains or losses in genomic DNA.
