Subtelomeric study of 132 patients with mental retardation reveals 9 chromosomal anomalies and contributes to the delineation of submicroscopic deletions of 1pter, 2qter, 4pter, 5qter and 9qter.
BACKGROUND
Cryptic chromosome imbalances are increasingly acknowledged as a cause for mental retardation and learning disability. New phenotypes associated with specific rearrangements are also being recognized. Techniques for screening for subtelomeric rearrangements are commercially available, allowing the implementation in a diagnostic service laboratory. We report the diagnostic yield in a series of 132 subjects with mental retardation, and the associated clinical phenotypes.


METHODS
We applied commercially available subtelomeric fluorescence in situ hybridization (FISH). All patients referred for subtelomeric screening in a 5-year period were reviewed and abnormal cases were further characterized clinically and if possible molecularly.


RESULTS
We identified nine chromosomal rearrangements (two of which were in sisters) corresponding to a diagnostic yield of approx. 7%. All had dysmorphic features. Five had imbalances leading to recognizable phenotypes.


CONCLUSIONS
Subtelomeric screening is a useful adjunct to conventional cytogenetic analyses, and should be considered in mentally retarded subjects with dysmorphic features and unknown cause.
Sogaard
Marie
M
The John F, Kennedy Institute, Glostrup, Denmark. msg@cancer.dk
Tümer
Zeynep
Z
Hjalgrim
Helle
H
Hahnemann
Johanne
J
Friis
Birgitte
B
Ledaal
Paal
P
Pedersen
Vibeke Faurholt
VF
Baekgaard
Peter
P
Tommerup
Niels
N
Cingöz
Sultan
S
Duno
Morten
M
Brondum-Nielsen
Karen
K
D000015:Abnormalities, Multiple / Q000235:genetics; D000293:Adolescent; D000328:Adult; D001848:Bone Diseases, Developmental / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D020223:Chromosome Painting / Q000379:methods; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D019465:Craniofacial Abnormalities / Q000235:genetics; D005260:Female; D006130:Growth Disorders / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D013577:Syndrome; D016615:Telomere / Q000235:genetics*; D014178:Translocation, Genetic / Q000235:genetics