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  • Title: [Factors predisposing to chromosome pathology].
    Author: Zuffardi O, Maraschio P.
    Journal: Pathologica; 1983; 75 Suppl():96-102. PubMed ID: 6240016.
    Abstract:
    The frequency of chromosome anomalies at birth (1/161) is far less than that found in induced abortion specimens or spontaneous abortions (about 4%). Moreover, the risk of Down's syndrome significantly increases if the father is over 55 years old; however, recent findings show that in the majority of trisomy cases, 21 were of maternal origin and occurred primarily in the 1st meiotic division. It has long been debated whether individuals with augmented association of the chromosomes containing the genes for nucleolar organizers have a greater probability of nonmeiotic disjunction. As a whole, the trisomies are correlated to an increase in maternal age. The correlation is even greater if in addition to the average age of only those mothers of chromosomically normal abortions the average age of all mothers who go through with pregnancy is considered. Since, in studies on heteromorphism, it has been proven that most of the nondisjunctions of maternal origin occur in meiosis I, it is hypothesized that the most pronounced effect of maternal age on the trisomies for the small chromosomes can be correlated to the chiasmas in each bivalent. Also, the autoimmune diseases are a cause of chromosomic anomalies, between maternal thyroidal autoimmunity and nondisjunction of chromosome 21. The difference between mothers with Down's offspring, with or without thyroiditis, is significant for mothers between 17-34 years of age, while it is less for those between 35-49. Among other factors, the presence of certain chromosomic heteromorphisms has been considered a cause of chromosomic anomalies. The effects of radiation on the germinal cells can cause chromosomic aberrations which can be found in the peripheral blood. Frequency can be dependent on the amount of radiation. Also, viral infectious diseases can cause chromosomic anomalies such as breakage, gaps, and pulverizations, and these can continue for a long time after the disease. Additionally, there are nutritional factors which may need to be brought out and studied more carefully.
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