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

Abstract

Purpose: To further assess the frequency of subtelomeric aberrations in a selected population and to examine the feasibility of a clinical testing. Methods: Patients were selected based on the following criteria: (1) mental retardation (IQ Ͻ 70) or developmental delay with dysmorphic features; (2) a normal karyotype at the level of resolution of 450 to 500 bands; and (3) exclusion of other possible etiologies by a full genetic assessment and relevant tests. Fluorescence in situ hybridization (FISH) was performed using multiple subtelomeric probes.Abnormal findings were confirmed by 24-color spectral karyotyping or FISH with a specific subtelomeric probe, and family studies were carried out to determine inheritance. Results: Clinically significant aberrations were detected in 6 of 150 proband patients (4%), while deletion of the 2q subtelomeric region appeared to be a common variant (6%). Conclusions: FISH with multiple subtelomeric probes is a valuable clinical test for establishing a definitive diagnosis for patients with unexplained mental retardation/developmental disorders. Genet Med 2001:3(6):416 -421.

The 2q37-deletion syndrome: an update of the clinical spectrum including overweight, brachydactyly and behavioural features in 14 new patients

“…The 2q polymorphism is a common condition in the population (5%). 34 Indeed, three parents (out of eight families tested) had the 2q polymorphism. Moreover, considering the possible role of the 2q polymorphism as a predisposing factor for the largest distal 2q deletion, the family of P8 illustrates the opposite trend.…”

Cytogenetic findings in patients with intellectual disability and/or multiple congenital anomalies

“…The association of translocations with poor obstetric history, fertility failure, amenorrhea, ambiguous genitalia and ID with MCA or DS has been well documented by various researchers. 20,21 Clinically, the most important single Robertsonian translocation involves chromosomes 14 and 21 (detected in two patients in this study); 4.0% of patients with DS are associated with this translocation.…”

Utility of subtelomeric fluorescent DNA probes for detection of chromosome anomalies in 425 patients

“…11 We previously reported the 2qter deletion variant/polymorphism to occur with a frequency of 9.4%. 12 Fan et al 18 similarly report the frequency of this variant to be at 6% in a population of idiopathic MR patients. The 2qter variant has been reported to be about 5% with the commercial probes that are larger in size compared with earlier versions.…”