Family with 22-derived marker chromosome and late-onset dementia of the Alzheimer type: II. Further cytogenetic analysis of the marker and characterization of the high-level repeat sequences using fluorescence in situ hybridization

Autor: Donald R. McLachlan, Sharon J. Bauer, Martin J. Somerville, Barbara Chodakowski, Ethylin Wang Jabs, Dorothy A. Miller, Maire E. Percy, Thomas G. Dearie, Anne Lennox, Antonio Baldini
Rok vydání: 1993
Předmět:
Zdroj: American Journal of Medical Genetics. 47:14-19
ISSN: 1096-8628
0148-7299
DOI: 10.1002/ajmg.1320470104
Popis: We have further characterized an unusual 22p+ marker chromosome with a double nucleolus organizer region (dNOR) previously identified in a family with late-onset dementia of the Alzheimer type. G-banding and morphology of the marker's q arm were typically normal. However, the p+ arm had a terminal cytological satellite and a GT-positive region at the midpoint. Standard C-banding documented 2 C-positive regions: one was associated with the primary centromere; the other, which was at the midpoint of the p arm, was not associated with a constriction. With replication-banding, there was a darkly staining region in the middle of the p+arm that resembled the pericentromeric region of a chromosome 21 or 22. Fluorescence in situ hybridization with pXlr 101, a probe recognizing the full repeating unit of rDNA, indicated that the marker had an unusually large rDNA region; with pU 1.2, a probe recognizing the human rDNA promoter, the signal was a doublet. The marker had 2 signals with a β-satellite probe, and a second signal in addition to that present at the primary centromere under low stringency with α-satellite probes and a classic satellite probe. Immunostaining of chromosome spreads after R-banding and ultraviolet (UV) denaturation showed that the major portion of the marker's p arm was highly methylated. © 1993 Wiley-Liss, Inc.
Databáze: OpenAIRE
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