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

M. E. Percy, T. G. Dearie, E. W. Jabs, S. J. Bauer, B. Chodakowski, M. J. Somerville, A. Lennox, D. R C McLachlan, A. Baldini, D. A. Miller

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Pages (from-to)14-19
Number of pages6
JournalAmerican Journal of Medical Genetics
Volume47
Issue number1
StatePublished - 1993
Externally publishedYes

Keywords

  • Alzheimer disease
  • chromosome 22
  • double nucleolus organizer region

ASJC Scopus subject areas

  • Genetics(clinical)

Fingerprint

Dive into the research topics of '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'. Together they form a unique fingerprint.

Cite this