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Interferon action and chromosome 21 trisomy (Down syndrome): 15 years later
1Southern Illinois University, School of Medicine, Department of Medical Microbiology Immunology, Springfield 62794-9230, USA.
Abstract:
A hypothesis relating interferon action and the chromosome 21 trisomy genotype and phenotype was presented in this journal in 1980. Since that time a number of additional genes involved in interferon action have been mapped to the distal Down Syndrome region of chromosome 21 and a growing literature has documented highly relevant pleiotropic effects of interferon in the brain. Thus, interferon continues to provide a potential basis for the phenotypic anomalies seen in the interferon supersensitive Down Syndrome patient. Further, the hypothesis that ribosomal RNA gene "satellite association" induced by interferon action is involved in the induction of chromosome 21 misdistribution at meiosis, is supported by extension of the cyclic correlation of Down Syndrome prevalence and virus epidemics, first observed by Stoller & Collmann in Australia from 1942 to 1964, to incidence data gathered by the CDC in the U.S. from 1968 to 1992. In addition, data from spontaneous abortuses and gametes assembled from the literature argue for a uniquely high frequency of chromosome 21 hyperploidy which suggests that the genes present on chromosome 21 play a role in its frequent misdistribution at meiosis. Taken together, these observations provide continued support for the hypothesis presented in 1980 that interferon action could be involved in the induction of both the trisomy 21 genotype and its resultant phenotype.
Insights
Interferon action may induce chromosome 21 misdistribution, potentially causing Down syndrome (trisomy 21). This hypothesis is supported by gene mapping and epidemiological data linking virus epidemics to Down syndrome prevalence.
Area of Science:
- Genetics
- Immunology
- Developmental Biology
Background:
- A 1980 hypothesis linked interferon action to chromosome 21 trisomy.
- Interferon-related genes are located in the Down syndrome region of chromosome 21.
- Interferon exhibits pleiotropic effects in the brain, relevant to Down syndrome phenotypes.
Purpose of the Study:
- To re-evaluate the hypothesis that interferon action is involved in Down syndrome (trisomy 21) etiology.
- To explore the role of interferon in chromosome 21 misdistribution during meiosis.
- To investigate the connection between interferon, ribosomal RNA gene satellite association, and Down syndrome prevalence.
Main Methods:
- Literature review of gene mapping studies for interferon-related genes on chromosome 21.
- Analysis of epidemiological data correlating Down syndrome prevalence with viral epidemics.
- Examination of data on spontaneous abortuses and gametes to assess chromosome 21 hyperploidy frequency.
Main Results:
- Additional interferon-related genes have been mapped to the distal Down syndrome region of chromosome 21.
- Epidemiological data support a cyclic correlation between virus epidemics and Down syndrome prevalence.
- High frequencies of chromosome 21 hyperploidy in abortuses and gametes suggest a role for chromosome 21 genes in meiotic misdistribution.
Conclusions:
- Interferon action remains a potential basis for Down syndrome phenotypic anomalies.
- Ribosomal RNA gene satellite association induced by interferon may contribute to chromosome 21 misdistribution.
- Observations support the hypothesis that interferon action is involved in inducing both the trisomy 21 genotype and its associated phenotype.