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Centromeric alphoid DNA heteromorphisms of chromosome 21 revealed by FISH‐technique
Author(s) -
Verma Ram S.,
Batish Sat Dev,
Gogineni Swarna K.,
Kleyman Svetlana M.,
Stetka Daniel G.
Publication year - 1997
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.1997.tb02426.x
Subject(s) - biology , genetics , centromere , chromosome , fluorescence in situ hybridization , trisomy , hybridization probe , heterochromatin , chromosome 21 , chromosome 16 , fish <actinopterygii> , microbiology and biotechnology , dna , gene , fishery
The centromeric heterochromatin of chromosome 21 has been evaluated by the fluorescence in situ hybridization (FISH) technique. It was found that the alphoid DNA sequences of pericentromeric regions of chromosome 21 were highly heteromorphic when a centromeric specific probe was hybridized to these sequences. The variations were so extreme that they could even be arbitrarily classified into at least five sizes by comparison with the length of the short arm (p) of chromosome 18. They are: negative (1); small (2); medium (3); large (4); and very large (5). We used 15 normal cases and 12 individuals with trisomy 21 (Down syndrome), and the incidences for these five classes were 3.0%, 22.7%, 59.2%), 13.6% and 1.5%, respectively. At least 3% of the chromosomes no. 21 did not show any trace of hybridization signals, which apparently escape detection at interphase level as well. Although, the variations observed in the present study are continuous, the proposed classification may yield some implications for future investigations.