Abstract |
Molecular analysis was performed to determine the parental origin of the extra number 21 chromosome in 20 couples following the birth of a child with standard trisomy 21. The parent of origin was successfully identified in 9 of 20 (45%) using five chromosome-21-specific DNA probes and eight restriction endonucleases by restriction fragment length polymorphism and dosage analysis; seven were of maternal and two of paternal origin. Utilizing the observed allele frequencies, the expected frequencies of informative homozygous matings [2(p2q2)] approximate 10% for seven of eight enzyme/probe combinations; the eighth, TaqI/pPW231F (D21S3), is 3%. The observed phenotype frequencies for all enzyme/probe combinations tested conform closely to predictions by the Hardy-Weinberg law. Strong linkage disequilibrium was observed between the DNA markers of EcoRI and TaqI with probe pPW236B; identical results were obtained with G-95 alpha 1-11a. We were able to demonstrate that although these two probes are of different size, and hence not identical, they detect the same TaqI and EcoRI polymorphisms; therefore both should be assigned to a single locus, D21S11.
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Authors | N L Rudd, L S Dimnik, C Greentree, K Mendes-Crabb, D I Hoar |
Journal | Human genetics
(Hum Genet)
Vol. 78
Issue 2
Pg. 175-8
(Feb 1988)
ISSN: 0340-6717 [Print] Germany |
PMID | 2892782
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
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Topics |
- DNA
(genetics)
- Down Syndrome
(genetics)
- Female
- Genetic Markers
- Humans
- Male
- Parents
- Polymorphism, Restriction Fragment Length
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