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

Genet Med. 2001 Nov-Dec;3(6):416-21. doi: 10.1097/00125817-200111000-00007.


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 < 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.

Publication types

  • Case Reports
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Child
  • Child, Preschool
  • Chromosome Aberrations*
  • Chromosome Banding
  • Chromosome Deletion
  • Chromosome Painting
  • DNA Probes
  • Female
  • Humans
  • In Situ Hybridization, Fluorescence / methods*
  • Infant
  • Infant, Newborn
  • Intellectual Disability / diagnosis*
  • Intellectual Disability / genetics
  • Karyotyping / methods*
  • Microscopy
  • Pedigree
  • Phenotype
  • Telomere / ultrastructure*
  • Translocation, Genetic
  • Trisomy


  • DNA Probes