Clinical Indication ID & Name
Prader-Willi syndrome
Test Group
Core
Test code
R48.1
Test name
N/A
Target genes
AS/PWS critical region
Test scope
n/a
Test method/ technology
Methylation testing
Optimal Family Structure
n/a
Eligibility Criteria
Molecular findings suggestive of Prader-Willi syndrome from, for example microarray, exome or genome analysis such as likely isodisomy or deletion at 15q11-13; OR
2. Clinical features strongly suggestive of Prader-Willi syndrome. All of the following should be present for a given age group:
Neonatal period: Hypotonia with poor suck
Age one month to two years:
• Hypotonia with poor appetite and suck in the neonatal period
• Developmental delay
Age two to six years:
• Hypotonia with history of poor suck
• Developmental delay
Age six to adulthood:
• History of hypotonia with poor suck (hypotonia often persists)
• Developmental delay
• Excessive eating with central obesity if uncontrolled externally
• Hypothalamic hypogonadism (when developmentally relevant)
Test code
R48.2
Test name
N/A
Target genes
AS/PWS critical region
Test scope
n/a
Test method/ technology
MLPA or equivalent
Optimal Family Structure
n/a
Eligibility Criteria
1. Molecular findings suggestive of Prader-Willi syndrome from, for example microarray, exome or genome analysis such as likely isodisomy or deletion at 15q11-13; OR
2. Clinical features strongly suggestive of Prader-Willi syndrome
Commissioning group
Core
Overlapping idications
where Prader-Willi syndrome is plausible but not highly likely. • R263 Confirmation of uniparental disomy test should be used to confirm likely UPD detected on methylation and copy number testing. Referrals for testing will be triaged by the Genomic Laboratory; testing should be targeted at those where a genetic or genomic diagnosis will guide management for the proband or family.
Address for samples/request forms
Genetics Laboratory
5th Floor Tower Wing
Guy’s Hospital
London
SE1 9RT
Contact with queries
Supporting documents
n/a
Education resources
n/a
Turn around times
All our turnaround times are listed on our specific turn around page https://southeastgenomics.nhs.uk/professionals/service-turn-around-times/
Request form download
Consent record
See consent guidance in test request form
Sample requirements
Sample Requirements Each sample must be sent labelled with 3 patient identifiers and must state the sample type clearly on the sample container. Sample Rejection Samples may be rejected for the following reasons: 1. Samples and request form do not show at least three identical patient identifiers 2. The sample is in the incorrect collection media 3. The request form is not sufficiently completed 4. The sample is not of sufficient volume 5. The sample is too old Sample Storage and Volume Required: Perirpheral blood in an EDTA tube: Adult and children 4 ml, Infants (0-2 years) 1 ml or a DNA sample (3-5µg of purified DNA). Where it is not possible to collect peripheral blood we will accept a saliva sample (please contact the lab for specific details). Storage, sample packing and transportation: Blood should be stored at 4°C where possible. Send at room temperature by first class post or by courier. Patient/Clinician Instructions: N/A Factors affecting performance of test/interpretation of results: Clotted samples are unsuitable for DNA analysis. Blood Samples in incorrect anticoagulant tubes may be rejected.