Giovanna Ferranti

Frequency of consanguineous marriages among parents and grandparents of Down patients

SummaryThe existence of a rare autosomal gene which in the homozygous state would cause mitotic nondisjunction in the Down zygote has been hypothesized in the past by Alfi et al. (1980). This hypothesis can be supported or contradicted by the study of the frequency of consanguineous marriages among parents of affected children. Our study on 242 children affected with Down syndrome does not show any increase in the frequency of consanguineous marriages among their parents with respect to the general population, and therefore does not support the hypothesis of an autosomal gene controlling mitotic nondisjunction. Our data do not show any increase in the frequency of consanguineaous marriages even among paternal and maternal grandparents of the affected children, thus not supporting the other possible explanation of an autosomal recessive condition in one of the patients parents which would cause meiotic nondisjunction.

Cytogenetic findings in 4952 prenatal diagnoses. An Italian collaborative study

SummaryThe development of prenatal diagnosis in Italy was made difficult by the restrictions of the old abortion law and only in recent years has a consistent number of cases been investigated. We report the experience on prenatal chromosome diagnosis of ten Italian centers participating in a collaborative study on 4952 diagnoses performed from 1972 to 1980. The main indication groups were: advanced maternal age (2882 cases), previous child with chromosome anomaly from parents with normal karyotype (847 cases), and chromosome anomaly in one parent (97 cases). The other indications for amniocentesis, including cases without a cytogenetic risk, have been assembled into a “miscellaneous” group (1126 cases). We found 125 abnormal fetal karyotypes (2.5%) of which 89 were unbalanced (1.8%). The frequencies and types of chromosome anomalies are reported in detail for each indication group and are compared with the corresponding ones from the European Munich Conference. The great majority of these Italian data were not included in the Munich report.

Monitoring of Pregnancies at Risk for Fanconi’s Anemia by Chorionic Villi Sampling

Two pregnancies at risk for Fanconis anemia have been monitored by a cytogenetic method in the first trimester of gestation. The rate of chromosome breakage was evaluated in spontaneous mitoses from a direct preparation of trophoblasts in one case and from mitoses obtained from standard cultures and from mitoses treated with diepoxybutane in both cases. Cytogenetic studies were carried out also at 16 weeks from amniotic fluid cells in one case, and in fibroblasts sampled from the aborted fetus in the other. In all the experimental conditions the mean frequency of breaks/cell was in the range of controls, suggesting that the fetuses were unaffected by Fanconis anemia. In one case the results have been confirmed by chromosome analysis at birth.