Detection of pathogenic copy number variants in children with idiopathic intellectual disability using 500 K SNP array genomic hybridization.
BACKGROUND
Array genomic hybridization is being used clinically to detect pathogenic copy number variants in children with intellectual disability and other birth defects. However, there is no agreement regarding the kind of array, the distribution of probes across the genome, or the resolution that is most appropriate for clinical use.


RESULTS
We performed 500 K Affymetrix GeneChip array genomic hybridization in 100 idiopathic intellectual disability trios, each comprised of a child with intellectual disability of unknown cause and both unaffected parents. We found pathogenic genomic imbalance in 16 of these 100 individuals with idiopathic intellectual disability. In comparison, we had found pathogenic genomic imbalance in 11 of 100 children with idiopathic intellectual disability in a previous cohort who had been studied by 100 K GeneChip array genomic hybridization. Among 54 intellectual disability trios selected from the previous cohort who were re-tested with 500 K GeneChip array genomic hybridization, we identified all 10 previously-detected pathogenic genomic alterations and at least one additional pathogenic copy number variant that had not been detected with 100 K GeneChip array genomic hybridization. Many benign copy number variants, including one that was de novo, were also detected with 500 K array genomic hybridization, but it was possible to distinguish the benign and pathogenic copy number variants with confidence in all but 3 (1.9%) of the 154 intellectual disability trios studied.


CONCLUSIONS
Affymetrix GeneChip 500 K array genomic hybridization detected pathogenic genomic imbalance in 10 of 10 patients with idiopathic developmental disability in whom 100 K GeneChip array genomic hybridization had found genomic imbalance, 1 of 44 patients in whom 100 K GeneChip array genomic hybridization had found no abnormality, and 16 of 100 patients who had not previously been tested. Effective clinical interpretation of these studies requires considerable skill and experience.
Friedman
Jm
J
Department of Medical Genetics, University of British Columbia, Vancouver, Canada. frid@interchange.ubc.ca
Adam
Shelin
S
Arbour
Laura
L
Armstrong
Linlea
L
Baross
Agnes
A
Birch
Patricia
P
Boerkoel
Cornelius
C
Chan
Susanna
S
Chai
David
D
Delaney
Allen D
AD
Flibotte
Stephane
S
Gibson
William T
WT
Langlois
Sylvie
S
Lemyre
Emmanuelle
E
Li
H Irene
HI
MacLeod
Patrick
P
Mathers
Joan
J
Michaud
Jacques L
JL
McGillivray
Barbara C
BC
Patel
Millan S
MS
Qian
Hong
H
Rouleau
Guy A
GA
Van Allen
Margot I
MI
Yong
Siu-Li
SL
Zahir
Farah R
FR
Eydoux
Patrice
P
Marra
Marco A
MA
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D018628:Gene Dosage / Q000235:genetics*; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D055815:Young Adult