Conditions seen by Clinical Genetics

The Clinical Genetics Department at Great Ormond Street Hospital sees adult and paediatric patients for a range of conditions.

Arranging Genetic Tests outside of Clinical Genetics

Please note that many genetic tests specified in the national genomic test directory can now be ordered by local care teams. This often provides a result quicker than through a referral to Clinical Genetics. If a pathogenic variant or variant of uncertain significance, is identified please refer the patient to Clinical Genetics. Alternatively, if genetic testing does not identify any pathogenic variants and there is a significant personal or family history of cancer or rare disease, please contact us for advice.

  • Genetic testing in England is arranged and funded centrally through the NHS Genomic Medicine Service, ensuring equity of access.
  • For information about genetic tests, who can request them and patient eligibility criteria, please see the National Genomic Test Directory.
  • Genetic testing is undertaken by the North Thames Genomic Laboratory Hub. Detailed guidance and instructions on arranging tests is provided on their website, along with Genetic Test Request forms that can be downloaded for use.
  • Consent: Please be aware that patient consent should always be obtained before requesting a genetic test. Find out more by consulting this example consent form. Further guidance regarding consent for genetic testing is also available from the Royal College of Physicians.
  • Consent is not required for storage of a DNA sample.
  • Training and support is available to cancer clinicians and clinical nurse specialists on genetic testing. These resources and information about upcoming training can be found here: You can also find national resources and information through GeNotes.

Rare Disease Service

Our clinicians can give advice on genetic testing and interpretation of genomic data including:

  • Diagnostic opinion for children with undiagnosed malformation syndromes and/or intellectual disability, including rapid genomic testing in critically ill children.
  • In order to avoid diagnostic delay, for non-urgent referrals please ensure that microarray testing has been completed, or at least initiated, prior to making a referral to our service.
  • Genetic counselling for families with known genetic and chromosomal conditions - this includes risks in future pregnancies and the need for testing of other family members.
  • Genetic counselling prior to prenatal testing, including invasive testing, non-invasive prenatal diagnosis (NIPD) and preimplantation genetic testing for monogenetic disorders (PGT-M).

Cancer Genetics Service

The Cancer Genetics team provide a specialist service for children and adults affected by or at risk of inherited forms of cancer. This includes risk assessment, genetic testing for cancer predisposition when clinically indicated, and onward referral for relevant screening or other management options.

We offer urgent diagnostic genetic testing for patients diagnosed with a cancer, where the result may directly impact their treatment options (such as surgical options or chemotherapy).

Patients with hereditary cancer predisposition syndromes can also be referred to our service to discuss their screening or risk-reducing options, and for support with family planning and family communication

Examples of families who may benefit from genetic assessment include those with a personal and/or family history of:

  • Breast cancer/ovarian cancer
  • Colorectal cancer and/or colorectal polyps
  • Endocrine tumours
  • Paediatric cancers
  • Kidney tumours
  • Retinoblastoma
  • Rare cancer types or young age of diagnosis

More details on criteria for referral to the Cancer Genetics team can be found in the National Genomic Test Directory.

We do review each referral individually, so please provide as much personal and family history information to assist with referral triage. If we reject a referral, we often provide written advice as to the reasons for this

Rare diseases not seen by the Clinical Genetics service

  • Alpha-1-antitrypsin deficiency: Genetic testing can be arranged by the local hospital laboratory or in general practice using the North Thames GLH Test request form. See R191 in the National Genomic Test Directory. A patient information leaflet is also provided below.
  • Carrier testing for rare recessive conditions: For conditions where carrier frequency is less than 1/70 in the general population, carrier testing is not available within the NHS. For further details please read the 'Autosomal recessive inheritance and carrier testing patient information leaflet' below.
  • Hypermobile Ehlers Danlos Syndrome (EDS) or Hypermobility Spectrum Disorder (HSD): Joint hypermobility is common in the general population and often familial. Only a small proportion of people with hypermobility will require genetic advice. They will usually have additional distinctive clinical features, as detailed in the Ehlers Danlos Referral Information Sheet below. Of those without additional features, some will have the relatively common 'Hypermobility Ehlers Danlos syndrome (hEDS)' and may have associated chronic pain and autonomic dysfunction. Currently there is no diagnostic genetic testing available for hEDS and no specific treatment or surveillance can be offered by the Clinical Genetics service. Management of hEDS symptoms should be through referral to relevant medical specialists. We are unable to accept referrals for patients with hEDS.
  • Familial Hyperlipidaemia: Referrals for hyperlipidaemia and hypercholesterolemia should be directed to your local lipid clinic. A list of UK lipid clinics can be found at the Heart UK website
  • G6PD: Refer the patient to their local haemoglobinopathy service.
  • Haemochromatosis: A genetic test can be arranged by the local hospital laboratory or in general practice using the North Thames GLH Test request form. See R95 in the National Genomic Test Directory.
  • Haemoglobinopathies: General management and diagnosis is undertaken by haemoglobinopathy and haematology services. We can however accept a referral if there are known disease-causing gene variants and the couple want to consider pre-implantation genetic testing (PGT-M).
  • Haemophilia: Refer the patient to their local haemophilia unit.
  • Infertility: Investigations can be carried by the GP or fertility specialist. Please then refer to us only if any abnormalities are found in the genetic investigations that require interpretation or counselling.
  • Isolated Cardiac Arrhythmia, Aortopathy and Cardiomyopathy: Genetic testing for affected individuals should be arranged by the patient's own specialist Cardiologist. Clinical screening and genetic testing in individuals with a family history of cardiomyopathy, arrhythmia, aortopathy, or sudden cardiac death is arranged via specialist Inherited Cardiovascular Disease centres, which can also provide access to a range of services needed for management in individuals found to be affected or carriers of the condition. Please refer at risk Adult family members to: the Inherited Cardiovascular Disease Unit at Inherited Cardiovascular Disease Unit at Barts Heart Centre, and at risk Paediatric family members to the Inherited Cardiovascular Disease Unit at GOSH, as per the referral guidance leaflets below.
  • Isolated Autism: We use the recommended Autism flow chart. We no longer accept referrals for children with autism unless they also have:
    • significant dysmorphic features
    • otherwise unexplained developmental delay
    • consanguinity
    • one or more affected siblings
    • microcephaly or macrocephaly (>2 SD from mean)
    • epilepsy
    • neurocutaneous abnormalities
    • a significant abnormality reported on array CGH or other genetic testing

Additional information can be found in the Genetics of Autism information leaflet below.

  • MTHFR: We do not offer MTHFR testing as it is not indicated in screening for thrombophilia. As per the American College of Medical Genetics and Genomics Practice Guidelines, 2013, there is no evidence of any clinical utility in testing for the C677T MTHFR variant. Testing for this variant is not offered within the NHS. MTHFR C677T is a common variant (polymorphism) in people of Northern European descent. About a third of the White British population would have one copy of this variant, and 10% two copies of the variant. Even those with two copies of the variant remain well as long as they have normal folic acid levels.
  • Recurrent Miscarriages: baseline investigations for couples with recurrent miscarriages are carried out by the obstetrics team. We can accept referrals if an abnormality is identified on the chromosomal/genetic investigations.
  • Thrombophilia: refer patient to the local thrombophilia clinic.

Cases not appropriate for the Cancer Genetics service

We review each referral individually, so please provide as much personal and family history information to assist with referral triage. If we reject a referral, we often provide written advice as to the reasons for this. The following are examples where Cancer Genetics referral may not be indicated:

  • People with a family history of cancer, who are unaffected themselves. Genetic testing, when appropriate, is most informative when first performed in a relative who has had cancer, in order to determine if there is a hereditary cancer predisposition causing the cancers in the family. Genetic testing is not routinely recommended for individuals without cancer, unless genetic testing has already identified a hereditary cancer predisposition in a relative.
  • Alternatively, if all relatives with cancer are deceased, please consult the National Genomic Test Directory and re-refer your patient with a completed family history questionnaire, if appropriate.
  • People with a cancer diagnosis, whose personal and/or family history do not meet current national genomic test directory criteria. Please refer these patients to a local cancer family history clinic for assessment.
  • Advice on hormone replacement therapy treatment for people with a family history of breast/ovarian cancer. Advice to women regarding the use of HRT should vary according to the individual clinical circumstances (such as age, severity of menopausal symptoms, and osteoporosis) and balancing the increased breast cancer risk against the daily impact of symptoms. More information can be found at Breast Cancer Now
  • People who have had direct-to-consumer genetic testing, or certain private genetic tests. We are not in a position to provide interpretation of privately arranged genetic testing. This includes direct-to-consumer testing and polygenic risk scores. Therefore, we are unable to accept referrals, either from clinicians or directly from patients, to interpret privately arranged genetic test results. Likewise, we are not in a position to offer advice on the management of pathogenic mutations that may contribute to conditions for which we do not routinely offer genetic testing. If a patient or physician chooses to undertake genetic testing privately, we strongly recommend that they do so under the guidance of a Clinical Geneticist or Registered Genetic Counsellor. There are several who offer private services in the London area.

Referral rejections

We may reject the following referrals if the patient is undergoing further genetic tests or medical assessments.

Microarray (detailed chromosome examination):

  • Patients presenting with intellectual disability, developmental delay, with or without dysmorphism or multiple (more than 3) congenital abnormalities will usually be eligible to have a microarray as a first line investigation
  • If a non-urgent referral is made for genetic investigations for a patient with one or more of the medical problems above, the referral will be rejected pending a discussion about the option of a microarray and the organisation of a microarray by the referring clinician. Complete the blood form to request a microarray test and send to the North Thames Genomics Laboratory Hub. Once a microarray is in process, the referral can be accepted. A genetic referral can still be made should the family decline the option of a microarray, following discussion with the referring clinician.
  • In urgent cases, such as newborn infants with a suspected chromosome syndrome, prenatal cases or acutely unwell patients, the referral will be accepted with or without a microarray.

Possible Marfan syndrome:

  • Where possible is is helpful for the patient to have a completed echocardiogram and ophthalmology reviews to rule out any concerns with the eyes, prior to being seen in the genetics clinic.
  • We can see patients where the possibility of Marfan syndrome or a related connective tissue disorder has been raised to i) take a family and personal history, ii) to examine for systemic features of Marfan syndrome and iii) to consider the possibility of other overlapping conditions.

Information sheets about conditions not seen by Clinical Genetics

Alpha 1 Antitrypsin information leaflet for patients:

Alpha-1 Antitrypsin deficiency (85 KB)

Hereditary Haemochromatosis information leaflet for patients:

Hereditary Haemochromatosis (78 KB)

Genetics of Autism information leaflet for families

Certain types of Autism (262.49 KB)

Autosomal recessive inheritance and carrier testing patient information leaflet

Carrier testing in recessive conditions (124.7 KB) 

Ehlers Danlos Referral Information Sheet (0 bytes)

Referral Guidance for Cardiomyopathy (Children) (0 bytes)

Referral guidance for Cardiomyopathy (Adults) (0 bytes)

Referral guidance for Aortopathy (Children) (0 bytes)

Referral guidance for Aortopathy (Adults) (0 bytes)

Referral guidance for Haemoglobinopathy (0 bytes)