Detailed characterization of 12 supernumerary ring chromosomes using micro‐FISH and search for uniparental disomy

Abstract

Twelve patients with varying degrees of mosaicism for a supernumerary ring chromosome were studied. The ring chromosomes were characterized using microdissection in combination with degenerate nucleotide-primed polymerase chain reaction (PCR) and reverse painting (micro-FISH). This method made it possible to determine the chromosomal origin of the ring chromosomes in detail, and thus to compare the phenotypes of similar cases. Eleven of the marker chromosomes were derived from the most proximal part of 1p, 3p, 3q, 5p, 7q, 8p, 8q, 9p, 10p and 20p. One marker chromosome had a complex origin, including the proximal and the most distal part of 20q. Eight of the families were also investigated for uniparental disomy (UPD) using microsatellite analysis. One case with maternal UPD 9 was found in a child with a ring chromosome derived from chromosome 9, r(9)(p10p12).

Cytogenetic and molecular evaluation of 241 small supernumerary marker chromosomes: Cooperative study of 19 Italian laboratories

“…[17][18][19] The use of PACs/BACs and the evolution of FISH techniques (reverse painting and CGH), CGH microarray, and so forth have made it possible to "size" sSMCs and define their content very finely. However, the literature contains few descriptions of sSMCs grouped by marker type from which karyotype-phenotype correlations can be deduced to allow correct genetic counseling.…”

Characterization of Small Supernumerary Marker Chromosomes By A Simple Molecular and Molecular Cytogenetics Approach

“…However, an inherited sSMC may be connected with clini cal abnormalities in exceptional cases ( [8] case I). If origin of the sSMC is to be clarified, go to 4).…”

“…This has been refined to 7% (for sSMC from chromosomes 13, 14, 21 or 22) and 28% (for all non-acrocentric autosomes) [5] and has recently been suggested to be 26-30% [1,6]. Also, BJMG 10/1 (2007) 33-37 10.2478/v10034-007-0006-5 generally speaking, sSMC transmitted by normal sSMC carriers to their progeny are not correlated with clinical problems [7], although exceptions have been described [8].…”

A systematic analysis of small supernumerary marker chromosomes using array CGH exposes unexpected complexity

“…Gains involving the pericentromeric region of chromosome 8 are reported in individuals typically with developmental delay/mental retardation and nonspecific minor abnormalities. [43][44][45] The presence of a large interstitial homozygous region in the long arm of chromosome 8, not involving the region of copynumber gain, is suggestive of uniparental heterodisomy (UPD8) occurring during meiosis I with two recombination events in the 8q arm. The coexistence in this patient of a marker chromosome with material from the pericentromeric region of the 8p arm and the uniparental heterodisomy is a rare occurrence.…”