Subtelomeric rearrangements detected in patients with idiopathic mental retardation

Abstract

A screening for submicroscopic rearrangements was performed in 111 patients with idiopathic mental retardation (MR) using fluorescence in situ hybridization (FISH) probes from the subtelomeric regions of all chromosome arms. Ten cryptic rearrangements were found (9%): five de novo deletions; one unbalanced de novo translocation; three unbalanced inherited translocations; and one unbalanced recombinant chromosome, inherited from a parent with a pericentric inversion. In addition, 50 of the patients were screened for interstitial rearrangements with spectral karyotyping (SKY), but no aberrations were found. However, SKY detected the subtelomeric rearrangement in three of the four unbalanced translocations. Dysmorphic features were present in all patients with detected subtelomeric rearrangements.

Detection of submicroscopic aberrations in patients with unexplained mental retardation by fluorescence in situ hybridization using multiple subtelomeric probes

“…19,[23][24][25]27 When all the data are considered, the average prevalence of the 2qtel deletion is approximately 5%. In our study, 6% of the patients had the 2qtel deletion, and segregation analysis of the 2qtel deletion in relevant family members showed no correlation with mental retardation and other phenotypic anomalies.…”

Telomeres: a diagnosis at the end of the chromosomes

“…The mother was a carrier of the balanced t(9;13). Rossi et al 12 reported a de novo 9qter deletion in a moderately mentally retarded child with facial dysmorphism (not further specified), and also Anderlid et al 32 in a 25 year old severely mentally retarded woman with epilepsy, synophrys, hypertelorism, and strabismus, and Rio et al 14 in a severely mentally retarded female with obesity, abnormal genitalia, and hyperactivity.…”

“…A der(2)t(2;7)(q73;q36) was detected in a severely cognitively retarded 3 year old boy with facial dysmorphism (prominent forehead, downward slanting palpebral fissures, arched eyebrows, long eyelashes, small mouth with short philtrum and thin upper lip), a few café au lait spots, pectus carinatum, and talipes equinovarus. 30 Mildly mentally retarded patients with 2qter deletions and an inconsistent clinical phenotype have been reported [31][32][33] and Figure 1 Clinical photographs of various patients with subtelomere deletions.…”

“…This mild variant of WHS is also known as Pitt-Rogers-Danks syndrome with growth retardation, microcephaly, mental retardation, seizures, and a distinctive facial appearance. Anderlid et al, 32 in their series of patients screened for subtelomeric deletions, described a 3 year old girl with severe mental retardation, no language, epilepsy, short stature, hypertelorism, downward slanting palpebral fissures, broad forehead, and low set ears with a deletion that was not detectable by high resolution chromosome analysis, but included WHSCR. The critical deletion region has been narrowed down to 165 kb at 4p16.3.…”

Practice parameter: Evaluation of the child with global developmental delay [RETIRED]

“…Nine studies used fluorescence in situ hybridization (FISH) of subtelomeric probes to detect chromosomal rearrangements [68][69][70]72,[74][75][76][77][78] and two studies used microsatellite markers. 71,73 The latter approach is able to detect uniparental disomy (inheritance of both copies of one chromosome from the same parent).…”