Cytogenetics Service


Comprehensive constitutional chromosome analysis is offered for a range of referrals (postnatal and prenatal) using high density oligonucleotide microarrays, G-banding karyotyping and fluorescence in situ hybridization (FISH).  Other DNA based cytogenetics tests employed by the laboratories include quantitative fluorescence polymerase chain reaction (QF-PCR) and multiplex ligation probe amplification (MLPA).


Samples can be forwarded to other laboratories for tests not available in-house  e.g. prenatal samples for rapid QF-PCR testing, or prenatal and parental bloods for haemaglobinopathy testing. Cultured cells can be forwarded to specified locations as requested - please contact the lab to arrange this.


Cytogenetic testing:


Types of referral  
 Culturing cells

 Information sheet

 Disorders of sexual development and infertility   Information sheet
 Parental cytogenetic testing  Information sheet
 Postnatal microarray  Information sheet
 Pregnancy loss investigations using MLPA and QF-PCR  Information sheet
 Prenatal microarray  Information sheet
 Rapid aneuploidy testing for neonates  Information sheet
 Rapid prenatal aneuploidy testing  Information sheet





June 2021


Test backlogs


Non-urgent requests for the following tests are currently not being reported within the NHSE guidance turnaround time target of 42 days:


Chromosomal microarray (current TAT approximately 3 months)


We are actively monitoring and working on these backlogs to improve the situation for our users. Please contact the laboratory for any clinically urgent cases as these may be able to be prioritised and reported within the target turnaround time.


Please contact the laboratory if you have any concerns or feedback about a specific case.



Downloadable documents: 



Sending samples to the cytogenetics laboratory


It is the responsibility of the patient's clinician to request a laboratory service/test and to ensure that all samples are correctly labelled and request forms completed to a minimum standard.


Consent is not required for DNA storage.  It is the responsibility of the clinician to obtain consent before requesting a genetic test.


Blood Samples


5ml venous blood in plastic EDTA bottles (>1ml from neonates) for DNA-based tests (e.g. microarray).


2ml venous blood in plastic lithium heparin bottles (at least 1ml from neonates).


Sample must be labelled with:


  • Patient's full name (surname/family name and given/individual name)
  • Date of birth and unique hospital/NHS number
  • It is desirable to have the date and time sample was taken and/or location as well the name of the person who took the sample


Prenatal Samples


Tissue type and date of biopsy should be clearly documented on the referral information together with the name of the person who took the sample.


In the case of twins, special attention must be given to the identity of each sample.


Minimum criteria:


  • Patient's full name (surname/family name and given/individual name)
  • Date of birth and/or unique hospital/NHS number


DNA Samples


The Association for Clinical Genomic Science (ACGS) guidelines recommend at least two pieces of identifying information on every sample tube.


  • Patient's full name (surname/family name and given/individual name)
  • Date of birth and/or unique hospital/NHS number
  • Other information provided with referrals should include a pedigree, where appropriate, with the full names of known individuals and correct family identifiers
  • If results are received e.g. allele numbers, a full explanation of the terminology should be included


Samples which do not meet these criteria may be rejected.
© 2011 Great Ormond Street Hospital for Children NHS Trust