The role of Q-banding in the cytogenetic study of human spontaneous abortions

Abstract

<p>The discovery of Q-banding made it possible to identify every member of the human chromosome complement. Spontaneous abortions known to have a better than average chance of presenting with a chromosome anomaly were selected for cytogenetic analysis. A highly successful technique for culturing chorion from these specimens was developed. Direct chromosome preparations were obtained from the coverglasses on which the fibroblasts were subcultured. The characteristics of each specimen were noted as that as the information pool gives, it may be possible to define abortion syndromes.</p> <p>Fifty-nine per cent of the specimens selected were abnormal. These abnormalities included trisomies 2, 8, 14, 16 and 22, triploidy and tetraploidy. Vesicular villi, maternal age over 40 and conception coincident with maternal ingestion of contraceptives were found to be excellent forcasters of chromosome anomalies. Only one embryo, 69, XXY, in which congenital malformations could be identified was collected during the duration of this project. A possible polymorphism in a non-heterochromatic region of chromosome 17, in a 16-trisomy specimen, was noted.</p> <p>Heteromorphic bands have made it possible to distinguish between the members of a homologous pair of chromosomes 3, 4, 13, 14, 15, 21 and 22. A study of such markers in a twin abortus allowed for speculation on the zygosity of the embryos. Similar polymorphisms were used to determine whether the extra set of chromosomes in two triploid abortuses was of maternal or maternal origin. Distribution of these marker chromosomes was also used to determine when in meiosis the event of abnormal development occurred. The point was stressed, that some cell-to-cell variability does occur in these heteromorphic Q-bands and that great care must be taken in distinguishing maternal and paternal marker chromosomes, before the distribution of these parental chromosomes can be used to make statements about abnormal development events.</p> <p>Heteromorphic bands have made it possible to distinguish between the members of a homologous pair of chromosomes 3, 4, 13, 14, 15, 21 and 22. A study of such markers in a twin abortus allowed for speculation on the zygosity of the embryos. Similar polymorphisms were used to determine whether the extra set of chromosomes in two triploid abortuses was of maternal or paternal origin. Distribution of these marker chromosomes was also used to determine when in meiosis the event of abnormal development occurred. The point was stressed, that some cell-to-cell variability does occur in these heteromorphic Q-bands and that great care must be taken in distinguishing maternal and paternal marker chromosomes, before the distribution of these parental chromosomes can be used to make statements about abnormal developmental events.</p>