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Isochromosome 18p Results from Maternal Meiosis II Nondisjunction


Kotzot, Dieter; Bundscherer, Gertrud; Bernasconi, Fabiana; Brecevic, Lukrecija; Lurie, Iosif W; Basaran, Seher; Baccicchetti, Carlo; Höller, Adelheid; Castellan, Claudio; Braun-Quentin, Cordula; Pfeiffer, Rudolph A; Schinzel, Albert (1996). Isochromosome 18p Results from Maternal Meiosis II Nondisjunction. European Journal of Human Genetics, 4(3):168-174.

Abstract

Microsatellite analysis with 13 microsatellites spread over 18p was performed to determine the origin of the marker chromosome in 9 patients with additional metacentric marker chromosomes. Phenotypes and banding patterns suggested that the markers were isochromosomes 18p. Maternal origin was determined in all 8 cases where both parents were available for study. Six cases showed 3 alleles (one paternal, one maternal each in single and double dose) of informative markers located close to the telomere while markers close to the centromere on 18p were reduced to homozygosity (one paternal allele in single dosage and one maternal allele presumably in triple dosage). A similar result was obtained in the patient with no parents available for examination. The other 2 patients were uninformative for maternal hetero- versus homozygosity, but at some loci the maternal band was clearly stronger than the paternal one whereas the opposite was never observed. Trisomy 18 differs from trisomy 21, XXX and XXY of maternal origin through a preponderance of meiosis II versus meiosis I nondisjunction. Thus, the results of our study and the advanced mean maternal age at delivery of patients with additional i(18p) indicate that in most if not all cases the marker chromosome originates from maternal meiosis II nondisjunction immediately followed by isochromosome formation in one of the 2 maternal chromosomes 18. Possible explanations of these results include a maternally imprinted gene on 18q with a lethal effect if the paternal homologue is lost and a mechanism through which nondisjunction in some cases could be connected with isochromosome formation.

Abstract

Microsatellite analysis with 13 microsatellites spread over 18p was performed to determine the origin of the marker chromosome in 9 patients with additional metacentric marker chromosomes. Phenotypes and banding patterns suggested that the markers were isochromosomes 18p. Maternal origin was determined in all 8 cases where both parents were available for study. Six cases showed 3 alleles (one paternal, one maternal each in single and double dose) of informative markers located close to the telomere while markers close to the centromere on 18p were reduced to homozygosity (one paternal allele in single dosage and one maternal allele presumably in triple dosage). A similar result was obtained in the patient with no parents available for examination. The other 2 patients were uninformative for maternal hetero- versus homozygosity, but at some loci the maternal band was clearly stronger than the paternal one whereas the opposite was never observed. Trisomy 18 differs from trisomy 21, XXX and XXY of maternal origin through a preponderance of meiosis II versus meiosis I nondisjunction. Thus, the results of our study and the advanced mean maternal age at delivery of patients with additional i(18p) indicate that in most if not all cases the marker chromosome originates from maternal meiosis II nondisjunction immediately followed by isochromosome formation in one of the 2 maternal chromosomes 18. Possible explanations of these results include a maternally imprinted gene on 18q with a lethal effect if the paternal homologue is lost and a mechanism through which nondisjunction in some cases could be connected with isochromosome formation.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Medical Genetics
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Scopus Subject Areas:Life Sciences > Genetics
Health Sciences > Genetics (clinical)
Uncontrolled Keywords:Genetics (clinical), Genetics, Tetrasomy 18p, Isochromosome 18p, Fluorescence in situ hybridization, FISH, Chromosome aberration, origin of Meiotic nondisjunction
Language:English
Date:1 January 1996
Deposited On:18 Apr 2023 14:53
Last Modified:29 Apr 2024 01:37
Publisher:Nature Publishing Group
ISSN:1018-4813
OA Status:Closed
Publisher DOI:https://doi.org/10.1159/000472191
Official URL:https://www.nature.com/articles/000472191
PubMed ID:8840117
Other Identification Number:alte DOI: 10.1159/000472191