Investigation of suspected chromosome imbalance in patients with learning difficulties multiple congenital abnormalities unexplained epilepsy or other developmental disorders


In many patients with unexplained developmental delay, learning difficulties, multiple congenital abnormalities (MCA), behavioural disorders, dysmorphism or other developmental disorders, the conditions are caused by chromosome imbalance due to loss or gain of dosage sensitive genes or disruption of normal gene expression. The imbalance may be due to extra chromosomes (aneuploidy), unbalanced structural rearrangements or submicroscopic deletions or duplications.

Referral information

We accept blood (4ml in EDTA) or mouthwash samples from children and adults with a suspected chromosome imbalance. Follow up testing is also offered to family members of patients who have been diagnosed with chromosome imbalance to establish the inheritance of the imbalance and evaluate reproductive risks.

Microarray Comparative Genomic Hybridisation (aCGH) is used as the frontline test to detect chromosome imbalance. Microarray testing can detect chromosome deletions or gains at a higher resolution than routine chromosome analysis.

Microarray testing cannot detect balanced chromosome rearrangements or polyploidy and may not detect unbalanced rearrangements present in mosaic form.

Follow up testing may be performed by microarray, chromosome analysis or Fluorescence In Situ Hybridisation (FISH), as appropriate.

Neonates with referral reasons indicative of aneuploidy (trisomy for chromosomes 13, 18 or 21) or sex chromosome disorders will be processed by QF-PCR in the first instance followed by microarray as a reflex test if a normal result is obtained from QF-PCR. In cases where QF-PCR shows an aneuploidy result, chromosome analysis will be instigated to evaluate the genetic mechanism and thus the parental recurrent risk.

Price & reporting times

NHS referrals to this service are paid for where there is an existing specialist commissioning contract for genetic testing. In other cases please contact the lab for prices.

Test Price (£ ex VAT) TRT *
Routine postnatal sample (no follow-up studies) POA 42 cd
Urgent postnatal sample (no follow-up studies) POA 14 cd
Postnatal sample referred with parental sample(s)

(Includes completion of any follow up studies)

POA 42 cd
Parental blood sample for inheritance studies POA 42 cd

Test validation & quality assurance - information for users

The OGT CytoSure Constitutional v3 8x60k microarray is not sold for diagnostic use. Due to probe distribution and density, all sizing information provided on reports is approximate. Anomalies may occur which cannot always be recognised or properly interpreted. Microarray analysis will not detect balanced rearrangements or polyploidy and may not detect unbalanced rearrangements present in mosaic form. aCGH does not provide any positional information. Analysis parameters are subject to change.

Sample requirements

Postnatal: 4ml EDTA blood sample (for microarray)

Postnatal (where aneuploidy or a sex chromosome disorder is suspected): 4ml EDTA blood sample (for microarray) AND 4ml Lithium Heparin blood sample for chromosome analysis.

Referral guidelines

Please see our referral guidelines for more information.