title: FISH screening for subtelomeric rearrangements in 219 patients with idiopathic mental retardation and normal karyotype.
abstract: Subtelomeric rearrangements are a common cause of idiopathic mental retardation (MR) accounting for 6.3-10.2% of moderate to severe cases and less than 1% of mildly retarded patients. We report on a cohort of 219 patients with idiopathic MR and normal 400-550 band karyotype screened for subtelomeric rearrangements by multiprobe Fluorescence in situ hybridization (FISH) in three Italian Genetics Centers. Twelve positive cases (5.5%) were found. Six were de novo deletions (1p, 7p, 9p, 9q, 20p, 22q) and four unbalanced translocations [a der(6)t(6q; 18p) and a der(18)t(8p; 18q) both de novo, a der(12)t(12p; 17q)mat and a der(2)t(2q; 17q) of unknown origin]. The remaining two cases were apparently balanced reciprocal translocations [a t(4p; 18q) and a t(1p; 16p)] of undetermined origin whose role in the pathogenesis of the clinical phenotype is doubtful. Dysmorphic features were present in all unbalanced patients, whilst a family history of MR was present in only four of them. The proposition that subtelomeric rearrangements are a significant cause of idiopathic MR is supported by our survey. Collection of the clinical data of positive patients will help to delineate the phenotype associated with the various subtelomeric abnormalities, to tailor healthcare services to the needs of these patients and their families and to determine the appropriate use of the test.
authors.affiliation: Medical Genetic Service, AUSL Imola, Viale Amendola, 8, 40026 Imola, BO, Italy. a.baroncini@ausl.imola.bo.it
authors.forename: Anna
authors.initials: A
authors.lastname: Baroncini
authors.forename: Francesca
authors.initials: F
authors.lastname: Rivieri
authors.forename: Antonella
authors.initials: A
authors.lastname: Capucci
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Croci
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Franchi
authors.forename: Alberto
authors.initials: A
authors.lastname: Sensi
authors.forename: Paola
authors.initials: P
authors.lastname: Battaglia
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Aiello
authors.forename: Elisa
authors.initials: E
authors.lastname: Calzolari
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002877:Chromosomes, Human / Q000235:genetics; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D016615:Telomere / Q000235:genetics*