Microarray comparative genomic hybridisation (CGH)

  • Microarray CGH utilises tens of thousands of DNA probes to simultaneously detect and accurately characterise copy number imbalance (deletions and duplications) from across the whole genome.

o   This test detects copy number imbalance at an extremely high resolution and can therefore detect previously cryptic copy number imbalance.

  • At BGL microarray CGH is the first line test for all patients referred with learning disability [ User Information Document download  ] (developmental delay/intellectual disability or autistic spectrum disorder) with or without additional congenital abnormalities or dysmorphism
  • Microarray CGH analysis is also undertaken for prenatal diagnosis on CVS and Amniotic Fluid samples where there have been foetal abnormalities detected on ultra sound scan, and on smaple from pregnancy losses.

Oligonucleotide Array

  • This laboratory currently use an oligonucleotide based microarray platform based upon a design developed by the International Standards for Cytogenomic Arrays (ISCA) Consortium

o   This ISCA design employs an evidence based approach to determine the best probe coverage to detect not only the commonly observed microdeletion and microduplication syndromes but also pathogenic imbalances               throughout the genome. The probe coverage varies across the genome and is highest across the exons and introns of genes important in the aetiology of developmental delay

o   This microarray allows whole genome scanning, with regions having increased or reduced resolution depending upon syndromic significance or published clinical associations.  The probe coverage varies across the genome     and is highest across the exons and introns of genes important in the aetiology of developmental delay.  Average resolution within the high priority regions - 189kb; medium priority region backbone - 375kb; lower priority     region backbone - 663kb

o   A lower resolution is used for samples from pregnancy losses


Clinical Feature Correlation

  • BGL also regularly contributes data to the DatabasE of Chromosomal Imbalance and Phenotype in Humans using Ensembl Resources (DECIPHER) in order to help facilitate the correlations between microarray CGH findings and clinical features.
  • Further information on microarray CGH, including patient information leaflets, is also available from the rare chromosome disorders charity Unique.


Microarray as a Technical Service

The Bristol Genetics Laboratory may be able to offer custom microarray solutions to meet specific diagnostic and research requirements.


Further information:


Last updated 30/10/2017

Test Information

Test information

Includes details of sample types, volumes, special precautions, turnaround times & reference ranges.