Postnatal Cytogenetic Diagnosis at Bristol Genetics Laboratory

Blood samples are used to study the chromosomes of babies, children or adults with a problem that may have a cytogenetic basis. The majority of referrals are from neonatal and infant units (birth defects), paediatric clinics (mental or physical handicaps and developmental delay, delayed growth and puberty problems), infertility clinics, obstetric departments (e.g. follow up testing following certain cytogenetic abnormalities found in foetal loss samples), and genetic counselling clinics.

For patients with learning difficulties and/or physical abnormalities, testing is carried out using PDF iconMicroarray Comparative Genomic Hybridisation (CGH).pdf, and for all other referrals by high resolution karyotyping  PDF iconPostnatal Cytogenetic Analysis.pdfwith additional fluorescence in situ hybridisation (FISH) studies on appropriate cases. Rapid aneuploidy screening and gender testing is carried out using PDF iconQF PCR.

Blood samples: for information on sample requirements follow link:  Sample requirements

Target reporting time:
Provisional ResultsUrgent confirmation of sex chromosome status and trisomy for chromosomes 13,18 or 21 in neonatal patients for samples arriving before 2.30 pm, within 3 calendar days after receipt of sample (most tests are reported in 1-2 working days, currently Monday to Saturday). Testing is carried out by QF PCR.

Final Results: Urgent samples within 10 calendar days. Non-urgent samples within 28 days. Please contact Bristol Genetics Laboratory to find out current reporting times.

Patients should be advised that:

  •  Occasionally samples fail to grow in culture (chromosome analysis); or extracted DNA is of insufficient quality for testing (microarray CGH and QF PCR).  These occur for <1% of samples.  Repeat samples would be required
  •  A repeat sample may be required should cell culture yield chromosomes of insufficient quality required for the reason for referral (high resolution karyotyping).
  •  Cell suspensions are routinely discarded 4 months after receipt.
  •  DNA is stored indefinitely or discarded on request.

It is important to let Bristol Genetics Laboratory (BGL) know of any recent blood transfusions that the patient may have received and to advise the patient that a repeat sample at a later date may be necessary.  

Last updated: 15th June 2018