Ring chromosome 20 syndrome without deletions of the subtelomeric and CHRNA4–KCNQ2 genes loci

Outcome of array CGH analysis for 255 subjects with intellectual disability and search for candidate genes using bioinformatics

“…The Wfth gene, UTS2R, is a receptor of Urotensin-II which was found to act as a neurotransmitter in regulating various neurobiological activities including anxiety and depression in a recent study (do Rego et al 2008). Other prioritized genes from our de novo CNVs that have been already found to be involved in ID include CHRNA4 (Elghezal et al 2007), EHMT1 (Kleefstra et al 2006), FEZ1 (Lee et al 2005), KCNQ2 (Borgatti et al 2004), MBD5 (Jaillard et al 2009), MEN1 (Nakajima et al 1999), SOX8 (Pfeifer et al 2000), OTX1 (Laroche et al 2008) and SF1 (Schlaubitz et al 2007). This suggests that, although further improvements for disease speciWcity are necessary, the candidate gene prioritization tools will remain a promising avenue for narrowing down functional genes harbored within pathogenic CNVs.…”

Cognitive Impairment and Abnormal Behaviour Related to Ring Chromosome 20 Aberration

“…Diagnostic evaluation revealed the existence of r(20) with mosaicism. High percentages of r(20) affected cells, ring instability and presence or absence of chromosome 20 deleted region have been considered to influence the severity of r(20) syndrome's clinical features (Nishiwaki et al 2005;Elghezal et al 2007, Garcia-Cruz et al 2000. Mosaicism within r(20) syndrome has been studied intensively.…”

Molecular analysis of ring chromosome 20 syndrome reveals two distinct groups of patients

“…The use of fluorescence in situ hybridisation (FISH) techniques have identified only three patients with deletions associated with ring chromosome 20 formation,18–20 while 13 patients had no deletions 11 12 15 16 21–23. As all of these studies used targeted FISH probes to identify deletions, it is still unclear if patients with R20 harbour smaller deletions outside of the location of the probes tested.…”