Detection of submicroscopic aberrations in patients with unexplained mental retardation by fluorescence in situ hybridization using multiple subtelomeric probes.
OBJECTIVE
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.
Fan
Y S
YS
London Health Sciences Centre and the University of Western Ontario, London, Canada.
Zhang
Y
Y
Speevak
M
M
Farrell
S
S
Jung
J H
JH
Siu
V M
VM
D000328:Adult; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002872:Chromosome Deletion; D020223:Chromosome Painting; D015342:DNA Probes; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000175:diagnosis* / Q000235:genetics; D007621:Karyotyping / Q000379:methods*; D008853:Microscopy; D010375:Pedigree; D010641:Phenotype; D016615:Telomere / Q000648:ultrastructure*; D014178:Translocation, Genetic; D014314:Trisomy
D015342:DNA Probes