Genetic Testing

Routine Genetic Testing

We provide genetic testing for patients diagnosed with hyperinsulinaemic hypoglycaemia. First line testing includes Sanger sequencing of the ABCC8 and KCNJ11 genes with a result issued within 1-2 weeks for newly diagnosed or medically unresponsive patients.

Testing of all known hyperinsulinism genes is available via targeted next generation sequencing analysis, this can be undertaken either as a first line test  for those who are responsive to treatment or as part of cascade testing once mutations in the ABCC8 and KCNJ11 genes have been excluded by Sanger sequencing. A list of the genes captured on this panel can be found here.

Routine diagnostic genetic testing is provided by the Exeter Molecular Genetics laboratory. Further information regarding costs and sample requirements can be found on the Exeter Diagnostic Laboratory website. For those families who are unable to afford testing, either through their own healthcare provider or by personal means, it is possible to apply for funding to cover the associated costs. This funding has been generously donated by Congential Hyperinsulinism International. Please contact  Dr Sarah Flanagan  at to discuss eligibility of individuals cases.

Prenatal testing

Prenatal testing may be possible for some families with a history of congenital hyperinsulinism. Please contact Dr Jayne Houghton ( to discuss individual cases.

Current Research Opportunities

Gene discovery studies

We are seeking to recruit patients with congenital hyperinsulinism of unknown cause for gene discovery studies. Using Medical Research Council and Wellcome Trust/Royal Society funds, next-generation sequencing will be employed to analyse the genome of individuals with persistent hyperinsulinism where mutations in the known genes have been excluded. Patients with hyperinsulinaemic hypoglycaemia that has persisted for ≥ 6 months are eligible to enrol in this study. A detailed clinical history along with samples from the affected individual, both parents and affected/unaffected siblings are required. Further information regarding this project can be obtained by emailing Dr Sarah Flanagan (

Incidental findings

Whilst the strategies that we employ result in a low prior probability of identifying mutations that predispose to other rare diseases it is possible that variants will be found. Our policy is however to report only results pertaining to the congenital hyperinsulinism in the patient.

Referral Documentation

Prior to sending samples to our laboratory a completed clinical request form should be returned via email.  A copy of this form should also be included with the samples from the patient and both parents.

Clinical request forms, Patient information sheets and a consent form are available for download from the following links:

Hyperinsulinism Request Form


Consent for Genetic Testing

Consent should be obtained at the time of sample collection and should comply with your own institutions policies. Our consent form can be used for this purpose if required. The completed form can be stored locally or sent with the samples for storage in the Exeter laboratory.


Sample Requirements

Blood: Please send at least two 4ml EDTA blood samples (1ml minimum for neonates, 5-10ml for children and 10-20ml for adults). Samples should be transported at ambient temperature. Blood samples in glass bottles are not accepted by the laboratory. Blood samples should be received by our laboratory within 5 days of venesection. Do not freeze blood samples – if storage is required prior to dispatch, blood samples can be stored at 4ºC (39.2ºF).

DNA: Please send a minimum of 5μg of DNA. DNA samples can be sent at room temperature.

Formalin-Fixed, Paraffin-Embedded (FFPE) Tissue: To test for loss of maternal heterozygosity of chromosome 11p15.5-11p15.1 in focal hyperinsulinism please send a minimum of 10 x 10μm of FFPE tissue from the pancreatic lesion. This should be sent at room temperature and with prior arrangement with the laboratory.

Other: In special circumstances, a saliva sample is acceptable. Please contact the laboratory for sample collection kits (Oragene). Please contact the laboratory prior to sending any other samples.

Transport: Please send samples by first class post or courier. Packaging should comply with UN3373 regulations for packaging and transportation of samples: 1. The sample should be wrapped in enough tissue to absorb the entire contents of the tube in the event of a breakage. 2. Seal the tissue with tape and place it into a specimen bag and seal. 3. Samples should then be placed in a sample box or padded envelope along with a copy of the referral information and the package marked ‘Pathological Specimen – Fragile With Care’.

Samples should be sent to the following address:

Department of Molecular Genetics
RILD level 3
Royal Devon and Exeter NHS Foundation Trust
Barrack Road
Exeter, EX2 5DW