Cytogenetics (Constitutional cytogenetics)

Cytogenetic analysis is performed according to the Professional Guidelines for the Association of Clinical Genomic Science, and the recommendations provided are dependent on the clinical indications given for each case.

Clinical details inform the investigation at all stages:

• Prior to analysis, clinical details may indicate, for example, that procedures such as chromosome breakage or leukaemic studies are required, which must be referred to a specialist centre.
• During analysis, they may indicate that extra cells should be screened to investigate the possibility of mosaicism (in a diagnosis of suspected Turner syndrome, for example) or that particular chromosomes must be targeted for high- resolution study, (chromosome 4 in suspected Wolf-Hirschhorn syndrome, for example).
• When the analysis has been completed, they may help to provide an accurate interpretation of the findings and, in some instances, prompt further investigations, such as FISH or molecular genetic studies.

When clinical details are not available, a routine analysis will be performed and a conditional report issued.

Samples

Cytogenetic studies require living cells, so please ensure that samples reach the laboratory as soon as possible.

If a delay before dispatch is unavoidable, samples may be stored in a refrigerator (4°C) but must not be frozen.

Samples sent more than 48 hours after sampling, or kept at temperatures below 4 ̊C or greater than 38 ̊C, may have inhibited growth.

Requesting additional tests

Any further tests that not requested at the time of sample receipt must be requested within:

• 1 week for tests requiring prenatal culture or cultured cells
• 2 weeks for DNA testing
• 2 weeks for cell culture testing
• 3 months for FISH testing

Samples can be stored for longer periods if specifically requested at the time of sample receipt.