Rare Disease Genomics at Bristol Genetics Laboratory
Genomic testing has a key role in the diagnosis of patients with Rare Disease and their relatives. The Bristol Genetics Laboratory (BGL) provides testing for a large number of genetic disorders, operating in partnership with the Exeter Genomics laboratory to ensure access to the full range of genomic tests as specified in the National Genomics Test Directory. Bristol provides specialist services for Cardiac, Renal, Neurology and lipid disorders, complemented by specialist endocrinology services at Exeter.
Enquiry Lines for Specialist Services are below:
Currently the referring clinician/Trust is responsible for funding testing carried out on submitted samples. A national commissioning model is in development. The majority of genomic tests are usually undertaken at the request of a specialist clinician.
Bristol provides laboratory services to support a range of research and clinical trials, including FAMCAT and renal RADAR, and work closely with clinical, academic and industry partners to help ensure that we deliver cutting edge, relevant and high quality Rare Disease Genomic services.
BGL are also the core genetic processing facility for the West of England Genomic Medicine Centre delivering high quality sample preparation and result validation services in partnership with Pathology and Clinical colleagues from across the region.
Reasons for Testing in RD:
• to confirm a clinical diagnosis in an affected individual – diagnostic testing
• to determine carrier status in a relative of an affected individual with a recessive disease – carrier testing
• to carry out prenatal diagnosis – prenatal testing
• to determine the risk of an individual developing symptoms of a dominant disorder – predictive testing
Samples suitable for DNA analysis are:
• lymphocytes taken from whole blood
• chorionic villus biopsies
• cultured amniotic cells
• cultured fibroblasts
• fresh or frozen tissue
• saliva samples/buccal cells (contact laboratory, sampling kits are available)
• paraffin embedded tissue
At least 3ml in EDTA tube (mixed well to avoid clotting) or 1-2ml for paediatric samples. Blood should be kept at room temperature or at 4°C and not be frozen before dispatch. Samples should be sent via 1st class post or equivalent.
Clinicians are encouraged to send samples to their local GLH for extraction. An aliquot of DNA can be forwarded to an external GLH for testing if a clinical letter of referral has been provided or other appropriate details given on the referral form.
Chorionic Villus Samples (CVS)
Please contact the laboratory when the clinical appointment is confirmed. Samples should be sent in appropriate transport medium to be received by the laboratory the same day as they are taken.
Prenatal results are usually available within 3-10 days (test dependent) provided appropriate information regarding the pathogenic variant in the family is already available.
Restrictions and Limitations:
DNA extraction and banking is generally available for disorders that clearly have a genetic basis. Where a test is not available, or unclear, the laboratory will store the DNA until further information is forthcoming. In these circumstances consent must be obtained for DNA storage.
Consent for Testing in Late Onset Disorders
For late onset neurological disorders such as Huntington disease, analysis is carried out to confirm a diagnosis in a patient showing clinical signs. Signed informed consent forms are required for referrals coming from specialists other than Clinical Genetics, Consultant Neurologists or Consultant Psychiatrists. The consent form should state that the individual and other family members understand the implications of a positive test result. If the proband is not able to provide a signature the laboratory will accept the signature of another family member or the main carer. We also require the signature of the specialist clinician. Please contact the lab for consent forms
Predictive testing (when the individual is at risk due to family history, but not showing clinical symptoms) will be undertaken only after appropriate genetic counselling and patients should be referred to the local Clinical Genetics Service http://www.uhbristol.nhs.uk/patients-and-visitors/your-hospitals/st-michaels-hospital/what-we-do/clinical-genetics/. The laboratory follows national guidelines. The result is given only to the requesting clinician or designated genetic counsellor.
Testing children for carrier status of an X-linked or autosomal recessive disorders
The laboratory follows the guidelines of the British Society of Genomic Medicine regarding genetic testing in children which protect a child’s right to privacy of his/her own genetic status and the right of the individual to make informed decisions. We reserve the right to withhold analysis of a child’s DNA until the child is able to provide his/her own informed consent for genetic testing where appropriate.
Private referrals including those for Fertility Studies
If samples from private patients are taken by a General Practitioner on behalf of a private clinic, the name and address of the private clinic/specialist consultant should be provided for reporting purposes, when forwarding to the laboratory.
Last updated: 24/07/2019