Silver-Russell Syndrome
Background and Standard Service Information
Silver-Russell syndrome, also known as Russell-Silver Syndrome or RSS is a malformation syndrome characterised by pre- and post-natal growth retardation.
While the exact aetiology of RSS is unknown, 10% of cases are due to maternal uniparental disomy of the entire chromosome 7 [mUPD(7)]; that is, the patient has inherited both copies of chromosome 7 from the mother and none from the father.
If present, mUPD(7) helps to make the diagnosis and indicates a low recurrence risk.
Specific clinical features of RSS include:
- Pre and post natal growth retardation.
- Cerebral haemorrhage.
- Feeding difficulties (at 16 months) triangular face.
- Downturned mouth, micrognathia (unusually small jaw).
- Broad high forehead.
- Pointed chin.
- Low prominent dysplastic ears.
- Clinodactyly (inward bending) of little fingers and toes and mild psychomotor developmental delay.
There is some evidence to suggest that mUPD(7) patients are less likely to have the triangular face, downturned mouth and micrognathia.
Essential referral information
In addition to standard patient and referral information:
- Patient’s symptoms.
- Any family history, including names and dates of birth of index case(s), and information regarding results of genetic testing.
Restrictions on testing
A referral to a clinical geneticist would be suggested prior to testing.
Tests offered
Diagnostic tests are performed for patients where clinical symptoms are suggestive of RSS and where the patient has been seen by a clinical geneticist. Microsatellite analysis of markers distributed along the length of chromosome 7 is performed on DNA extracted from both parents and the proband.
Samples required
Blood (3-5ml) in EDTA from the patient and each parent (3 samples in total).
Sensitivity of tests
Testing for UPD7 identifies only 10% of Russell Silver Syndrome cases.
Interpretation
Following laboratory analysis, a report is prepared indicating the presence or absence of maternal uniparental disomy of chromosome 7 [mUPD(7)] and an interpretation of the result.
Absence of mUPD(7) neither supports nor refutes a diagnosis of Russell Silver Syndrome, as less than 10% of sporadic RSS result from mUPD of chromosome 7.
The analysis carried out cannot exclude the possibility of segmental mUPD(7).
Target reporting times
This analysis is performed in batches; please contact the Molecular Genetics laboratory for next batch date.
Indicative times for routine testing are listed on the Molecular Genetics section of the website.
Please Contact Us if you have not received a report within a week of your patient being due back in clinic.
Requests for copies of reports on the day that your patient is in clinic cannot normally be accommodated.