Cells from a variety of samples (chorionic villus, amniotic fluid, blood and solid tissue) are cultured. Chromosomes are visualised using the G-banding technique. Normal males and females carry 46 chromosomes; two of these are the sex chromosomes. Chromosome analysis can be used to detect numerical abnormalities where there is complete loss (e.g. Turner syndrome, 45,X) or gain (e.g. trisomy 21 or Down syndrome, 47,XY,+21) of a chromosome. It can also detect structural chromosome changes where there is partial loss or gain of chromosome material. Chromosome analysis can also detect balanced structural anomalies such as reciprocal/Robertsonian translocations and inversions. We accept referrals encompassing a whole spectrum of referral reasons.
We accept blood samples from babies with ambiguous genitalia, suspected aneuploidies (trisomy 21, trisomy 13 or trisomy 18), for confirmation of a chromosome abnormality detected prenatally or for suspected sex chromosome aneuploidy. We also accept referrals from couples who are undergoing tests for infertility (IVF couples, azoospermic males) and patients with problems of sexual development (suspected Turner syndrome, suspected Klinefelter syndrome, delayed/premature puberty, or premature ovarian failure). We accept referrals for follow-up studies following detection of a chromosome abnormality either in another family member or following a pregnancy loss. We also accept referrals for patients with a family history of a balanced rearrangement (inversion, insertion or translocation). Samples from babies under the age of one month and from pregnant couples are classed as urgent samples (see reporting times).
We accept chorionic villus and amniotic fluid samples referred for increased nuchal translucency/thickness, increased serum screening risk, increased maternal age, abnormalities seen on ultrasound scan and a family history of balanced rearrangement. Samples will be tested by QF-PCR initially and will only proceeded to chromosome analysis if an aneuploidy is detected by QF-PCR We also accept samples referred for a family history of biochemical or molecular disorder; however these are only cultured by the cytogenetics department and the sample/cultured cells forwarded on to the relevant laboratory for specific testing. All prenatal samples are classed as urgent samples.
Solid Tissue Referrals
We accept skin punch biopsy samples from patients referred with suspected mosaicism (e.g. Hypomelanosis of Ito or Pallister-Killian syndrome). We also accept tissue samples from pregnancy loss but these samples are processed by QF-PCR and, where appropriate, by array CGH. It is essential that the date of delivery is included on all samples from pregnancy loss.
All eligible samples referred for chromosome analysis will be cultured and will undergo G-banded chromosome analysis. Samples from patients for array CGH analysis are not cultured for G-banding. Additional tests such as rapid aneuploidy screening using QF-PCR may also be requested and these must be specifically recorded on the referral card. Additional tests may be instigated by the laboratory if the chromosome analysis findings require further investigation.
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. The requirements for postnatal samples are a blood sample in Lithium heparin.
|Test||Price (£ ex VAT)||TRT *|
|Prenatal samples||POA||14 cd|
|Urgent postnatal blood sample||POA||14 cd|
|Routine postnatal blood sample||POA||42 cd|
|Solid tissue sample||POA||42 cd|
Test validation & quality assurance - information for users
Prenatal samples may also require an accompanying maternal blood sample [5ml in EDTA] to exclude the possibility of maternal cell contamination prior to reporting.
Standard chromosome analysis cannot detect chromosome deletions/duplications smaller than 5Mb in size and in some postnatal cases the quality of the chromosome preparations may be sufficient for the exclusion of numerical chromosome abnormalities and large structural chromosome rearrangements only. Chromosome analysis therefore cannot rule out a diagnosis of syndromes or conditions associated with smaller chromosome deletions or DNA variants. In these cases microarray or molecular genetic testing will be used instead of chromosome analysis.
5ml Lithium Heparin blood sample (1-2ml volume sufficient for younger/difficult to bleed patients)
Please see our referral guidelines for more information.