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Oxford University Hospitals NHS Foundation Trust

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specimen requirements - Molecular Genetics

General Specimen requirements

All samples MUST be accompanied by a referral form

Some samples may require a pre-referral form

Blood samples - DNA extraction & molecular testing

  • Container/Tube Type: EDTA tubes only
  • Delayed in Transit: >3 days
  • Temperature: Blood samples can be transported at room temperature. Blood samples must NOT be frozen
  • Volume:  Adults 2-5mls, Children 1-2mls, Fetal/Neonates 1ml

Blood spot

  • Container/Tube Type: N/A
  • Delayed in Transit: N/A (Note – lower yields are obtained with blood spots >1year)
  • Temperature: room temperature or refrigerated
  • Volume:N/A

Tissue samples (see below for muscle/liver biopsies for mitochondrial analysis)

  • Container/Tube Type: sterile Universals containing 10ml of tissue transport medium (supplied by the lab). Larger samples, which will not fit into a 20 ml Universal, should be sent dry in a plastic sterile container
  • Delayed in Transit: >3 days
  • Temperature: room temperature or refrigerated
  • Volume:  1cm square of the tissue is sufficient for the extraction of DNA
  • Further Information: Do NOT fix these tissues

Muscle/liver biopsies (for mitochondrial genetic analysis)

  • Container/Tube Type: not specified
  • Delayed in Transit: >2 days
  • Temperature: Snap frozen immediately in liquid nitrogen. Sent on dry ice
  • Volume:  Ideally >50mg tissue; if quantity is limited 5-10mg may be sufficient
  • Further Information: by courier, notify lab to expect receipt

Saliva samples

  • Container/Tube Type: Oragene.DNA collection vials (supplied on request by the lab)
  • Delayed in Transit: not specified
  • Temperature: Once the saliva sample has been mixed with the Oragene. DNA solution it is stable at room temperature for a few years (refer to the manufacturer's collection protocol supplied with each kit)
  • Volume: as per manufacturers collection protocol supplied with each kit
  • Further Information: Collection vials can be returned to the laboratory by 1st class post at room temperature

Urine samples (for mitochondrial genetic analysis)

  • Container/Tube Type: suitable sterile container, such as 20ml Universal
  • Delayed in Transit: >1 day
  • Temperature: room temperature
  • Volume:  20ml of an early morning sample
  • Further Information: courier if necessary

DNA samples

  • Container/Tube Type: not specified
  • Delayed in Transit: not specified. DNA samples should be sent door to door to arrive as soon as possible; i.e. 1st class post is satisfactory for most samples, overnight courier transport is preferable for urgent samples, e.g. for prenatal analysis
  • Temperature: room temperature or refrigerated
  • Volume:  required amounts are dependent on the tests requested – as a guide exome analysis needs 3ug at a concentration no less than 30ng/ul but less DNA is required for other tests. Contact laboratory for more information

Fixed tissues and tissue slides (FFPE)

  • Container/Tube Type: slides need to be in a slide box and packaged with sufficient padding
  • Delayed in Transit: not specified
  • Temperature: Room temperature
  • Volume:  N/A

Blood Samples – NIPD samples

  • Container/Tube Type: Streck tubes
  • Delayed in Transit: >1 day
  • Temperature: room temperature (do not refrigerate or freeze)
  • Volume: 5-10ml
  • Further information: samples need to be received in the lab by 12.00hrs on a Thursday and not on a Friday

Blood samples – for RNA extraction

  • Container/Tube Type: PaxGene tube (can be supplied on request by the lab). EDTA can be sent, but needs to be received within 24hrs of sampling
  • Delayed in transit: >1day Note: delay will lead to loss of RNA within cells; therefore the sample should be sent without delay
  • Temperature: room temperature or refrigerate
  • Volume: 2ml-10ml
  • Further information: samples must be received in the lab on Monday – Wednesday only

Delays in transit can result in sample failure or sub-optimal results. Blood is stable at room temperature for up to 7days. DNA yield will decrease over time (Nederhand R.J. et al., 2003 J of Thrombosis and Haemostasis 1: 987-991) therefore the sample should be sent without delay. Avoid sending samples to arrive at the weekend or just prior to a Bank Holiday.

All samples for molecular genetic analysis can be stored overnight at +4-8oC if there is an unavoidable delay between sample collection and dispatch. NIPD samples should be kept at room temperature.

For fresh tissues, the transit time is recorded as the time between the date the sample was taken and the date the sample arrived in the Genetics Laboratory. For non-fresh samples (i.e. those that have been stored by another department prior to sending to us for extraction, e.g. frozen tissues, paraffin blocks and blood spots) the date of ‘sample sent’ is used. Delayed in transit has been defined to enable the laboratory to monitor performance in order to comply with requirements of ISO15189.

Additional samples types may be accepted for analysis. Clinicians are advised to contact the laboratory to discuss specific specimen requirements prior to arranging specimen collection.

Last updated: 25 November 2019 by Claire Scott.

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