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. 1979 Jan 19;46(1):107-10.
doi: 10.1007/BF00278908.

Origin of the extra chromosome in trisomy 21

J F Mattei, M G Mattei, S Ayme, F Giraud

Origin of the extra chromosome in trisomy 21

J F Mattei et al. Hum Genet. .

Abstract

Of 61 families of children with trisomy 21, polymorphism of chromosome 21 elucidating the origin of the extra chromosome was found in 42. Nondisjunction was of paternal origin in 8 cases (19.04%) and the anomaly occurred with equal frequency during the first and second meiotic divisions. Maternal nondisjunction was demonstrated in 34 cases (80.95%), in which nondisjunction occurred by far the most often during the first meiotic division (29 cases). These results are in agreement with data from the literature, and suggest the existence of at least two different causes for chromosomal nondisjunction, the first being the same in both sexes and occurring in both meiotic divisions and the second specifically limited to the first meiotic division in the mother.

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