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Tests for adults

Sample requirements

Samples should ideally be sent to the Cytogenetics Department on the same day/next day. Where a delay is inevitable, such as over weekends, please store the sample in a refrigerator before sending on the next working day but please DO NOT FREEZE. Lithium heparin and EDTA tubes are suitable for cytogenetic testing depending on the test required, please see below, samples in other tubes will be rejected. For sample labelling, sample tube guide and completion of referral form criteria please see referral requirements.

Karyotype

Karyotype analysis will be carried out as appropriate depending on the clinical indication. For further information about the testing available and the clinical eligibility for these tests please refer to the National genomic test directory for rare and inherited disease and the Rare and inherited disease eligibility criteria. Please select the most appropriate code for the tests required.

Targeted G-banding

Targeted G- banding will be performed for specific referrals (see test directory above) or if a known chromosomal rearrangement is being investigated e.g. A known familial rearrangement; aneuploidy detected by FISH/QF-PCR/array testing; a particular pattern of CNVs detected by array testing suggestive of a balanced parental rearrangement.

Chromosomal Microarray

Microarray will be performed as appropriate depending on the clinical indication. For further information about the testing available and the clinical eligibility for these tests please refer to the National genomic test directory for rare and inherited disease and the Rare and inherited disease eligibility criteria. Please select the most appropriate code for the tests required.

For optimum interpretation of a microarray result, please provide a full clinical description of the patient.

If tests in addition to a microarray are required, please use appropriate code(s) for this from the test directory.

Some copy number changes (CNVs) may be reported as of uncertain significance and cannot be fully interpreted without investigation of parental samples. If required, parental blood samples will be requested in the report and a targeted analysis carried out for the copy number change observed in the original test of the proband. Microarray may detect incidental CNVs which may have implications for other family members.

Microarray will not exclude:

  • Balanced rearrangements
  • Small nucleotide variants (SNVs)
  • Fragile X
  • Single gene disorders
  • Some cases of Prader-Willi or Angelman Syndrome
  • Some cases of mosaicism

Fanconi Anaemia

Fanconi Anaemia referrals should be sent to Sheffield Diagnostic Genetic Services. Please see SDGS website for details.

 

Acceptance and rejection criteria

Lithium heparin is the preferred tube for karyotype testing. Bloods received in EDTA will be processed but the quality may be compromised. Bloods received in any other tube will not be processed. For microarray testing, blood in any tube other than EDTA will not be processed. The preferred volume is larger than 1ml, however for smaller volumes processing will be attempted but the test may be unsuccessful.

For urgent referrals and unrepeatable samples, if blood samples are received clotted or haemolysed, processing is usually attempted, however this may compromise the success or quality of the test. For a routine referral, the sample may be rejected and a repeat sample requested.

Referral categories and tests

Chromosomal microarray and karyotype

Cytogenetics testing including microarray and karyotype will be performed as appropriate depending on the clinical indication. For further information about the testing available and the clinical eligibility for these tests please refer to the National Genomic Test Directory. 

Karyotype or microarray may also be requested for inheritance studies following tests on a family member. Referrals for testing of asymptomatic relatives for a confirmed pathological familial variant should made be through Clinical Genetics. 

Please note, if a patient or partner is pregnant, or there is another clinical need for urgency please indicate this on the referral form.

FISH - Fluorescence In Situ Hybridisation

Microarray analysis is a more appropriate test for microdeletion syndromes. Other FISH testing may be suitable for certain familial cytogenetic rearrangements. Please contact the laboratory to discuss this testing prior to ordering a test.

Limitations

Please see our limitations of testing page.

Storage and further testing

Fixed cells from adult referrals is kept for 6 months from receipt date of the sample. After this time cases with a normal karyotype are discarded; cases with a structural chromosome abnormality are stored for 5 years. Subsequent genetic testing can be requested at any time within these periods but may not be possible depending on the quality of the material available.

Page last updated 24/09/2026. Please note that if printed, the information is only valid on the day of printing.