A novel 5q11.2 deletion detected by microarray comparative genomic hybridisation in a child referred as a case of suspected 22q11 deletion syndrome.
The 22q11 deletion syndrome (22q11DS) is a developmental syndrome comprising of heart, palate, thymus and parathyroid glands defects. Individuals with 22q11DS usually carry a 1.5- to 3-Mb heterozygous deletion on chromosome 22q11.2. However, there are many patients with features of 22q11DS without a known cause from conventional karyotype and FISH analysis. Six patients with features of 22q11DS, a normal chromosomal and FISH 22q11 analysis, were selected for investigation by microarray genomic comparative hybridisation (array CGH). Array-CGH is a powerful technology enabling detection of submicroscopic chromosome duplications and deletions by comparing a differentially labelled test sample to a control. The samples are co-hybridised to a microarray containing genomic clones and the resulting ratio of fluorescence intensities on each array element is proportional to the DNA copy number difference. No chromosomal changes were detected by hybridisation to a high resolution array representing chromosome 22q. However, one patient was found to have a 6-Mb deletion on 5q11.2 detected by a whole genome 1-Mb array. This deletion was confirmed with fluorescence in-situ hybridisation (FISH) and microsatellite marker analysis. It is the first deletion described in this region. The patient had tetralogy of Fallot, a bifid uvula and velopharyngeal insufficiency, short stature, learning and behavioural difficulties. This case shows the increased sensitivity of array CGH over detailed karyotype analysis for detection of chromosomal changes. It is anticipated that array CGH will improve the clinician's capacity to diagnose congenital syndromes with an unknown aetiology.
Prescott
Katrina
K
Molecular Medicine Unit, Institute of Child Health, University College London, 30, Guilford Street, London WC1N 1EH, UK.
Woodfine
Kathryn
K
Stubbs
Paula
P
Super
Maurice
M
Kerr
Bronwyn
B
Palmer
Rodger
R
Carter
Nigel P
NP
Scambler
Peter
P
D002648:Child; D002872:Chromosome Deletion; D002892:Chromosomes, Human, Pair 22; D002895:Chromosomes, Human, Pair 5; D002658:Developmental Disabilities / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D018895:Microsatellite Repeats; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis