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Example clinical scenario

A one-year-old girl is referred from primary care to paediatrics with a large left-sided abdominal mass that is ballotable. On examination, you note a large tongue, a left leg that is longer and wider than the right and a birthmark above the right eyelid. From her patient history, you see that she was born at 32 weeks’ gestation with a weight of 3.2 kilograms, and that she had problems maintaining her sugars during the neonatal period, necessitating top-up feeds.

When to consider genomic testing

According to consensus criteria published in 2018, which include a scoring system, a clinical diagnosis of Beckwith-Wiedemann syndrome (BWS) should be made (even in the absence of a confirmatory 11p15 result) when an individual scores at least four points (the cardinal features listed below attract a score of two and the suggesting features attract a score of one).

Cardinal features of BWS (two points per feature)

The cardinal features of BWS are:

  • macroglossia;
  • exomphalos;
  • lateralised overgrowth (hemihypertropy);
  • multi-focal and/or bilateral Wilms tumour or nephroblastomatosis;
  • hyperinsulinism (lasts beyond the first week of life); and
  • pathology: adrenal cortex cytomegaly, placental mesenchymal dysplasia, pancreatic adenomatosis.

Suggestive features of BWS (one point per feature)

Suggestive features of BWS are:

  • birth weight more than two standard deviations (2SD) above the mean (equivalent to the 98th percentile as described in the UK-World Health Organization growth charts);
  • facial naevus flammeus;
  • polyhydramnios and/or placentomegaly;
  • anterior ear lobe creases and/or posterior helical pits;
  • transient hypoglycaemia (resolves within the first week of life);
  • BWS-associated tumour (not bilateral or multi-focal Wilms tumour), unilateral Wilms tumour, hepatoblastoma, neuroblastoma, rhabdomyosarcoma, adrenocortical carcinoma and/or phaeochromocytoma;
  • nephromegaly and/or hepatomegaly; and
  • umbilical hernia and/or diastasis recti.

What do you need to do?

  • Consult the National Genomic Test Directory. From here you can access the rare and inherited disease eligibility criteria, which provides information about individual tests and their associated eligibility criteria. You can also access a spreadsheet containing details of all available tests.
  • To find out which genes are included on different gene panels, see the NHS Genomic Medicine Service (GMS) Signed Off Panels Resource.
  • Decide which of the panels best suits the needs of your patient or family. Where BWS is clearly suspected and the patient meets the criteria discussed above, the following should be prioritised:
    • R49 Beckwith-Wiedemann syndrome: Methylation testing and multiplex ligation-dependent probe amplification (MLPA) initially; then, if these tests return negative results and clinical suspicion of BWS is strong, single gene sequencing for CDKN1C may also be completed.
  • If the patient does not meet the clinical criteria for BWS but has hemihypertrophy, macroglossia or regional overgrowth, consider the following:
    • R50 Isolated hemihypertrophy or macroglossia: Methylation testing and MLPA; and/or
    • R110 Suspected segmental overgrowth disorders: small panel and MLPA.
  • If the patient does not meet the clinical criteria for BWS but has a suspected generalised overgrowth-intellectual disability syndrome, with a height and/or head circumference at least two standard deviations (2SD) above the mean in association with a learning disability, consider the following:
  • For tests that are undertaken using WGS, including R27, you will need to:
  • For tests that do not include WGS, including R49, R50 and R110:
    • you can use your local Genomic Laboratory Hub test order and consent (RoD) forms; and
    • parental samples may be needed for interpretation of the child’s result. Parental samples can be taken alongside that of the child, and their DNA stored, or can be requested at a later date if needed.
  • The majority of tests are DNA-based, and an EDTA sample (purple-topped tube) is required. Exceptions include karyotype testing and DNA repair defect testing (for chromosome breakage), which require lithium heparin (green-topped tube).
  • R27 is a large WGS ‘super panel’, and requesting if currently requires authorisation from clinical genetics.
  • Information about patient eligibility and test indications was correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.

Resources

For clinicians

References:

For patients

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  • Last reviewed: 24/03/2023
  • Next review due: 04/03/2024
  • Authors: Dr Hassan Shakeel
  • Reviewers: Dr Amy Frost, Dr Eleanor Hay, Dr Emile Hendriks, Professor Kate Tatton-Brown