New service available: R311 NIPD for spinal muscular atrophy

Definitive non-invasive prenatal diagnosis (NIPD) by relative haplotype dosage analysis (RHDO) is possible using cffDNA in pregnancies at risk of spinal muscular atrophy for confirmed carrier couples (including couples who are carriers of the same variant).

This test is only applicable to couples
1) who are known carriers AND
2) DNA is available from the affected proband or a confirmed unaffected child

Relative haplotype dosage analysis will be used to determine if the fetus has inherited the high risk allele from both parents.

NIPD by RHDO is not currently possible for consanguineous couples. Testing may not be possible in multiple pregnancies including vanishing twin. In such cases contact the laboratory to discuss.

Patients must meet the referral criteria for the specific test indication as outlined in the National Genomic Test Directory rare and inherited disease eligibility criteria document.

The nationally agreed turnaround time is 21 days for non-invasive prenatal diagnosis.

Samples required

Pregnant Patient

• 2 x 10ml venous blood in cell stabilising bottles (PAXgene Blood ccfDNA or Streck Cell-Free DNA)
• The minimum gestation (by scan) is 9wks for accepting a sample.

Paternal blood (5ml EDTA) or DNA Proband (or confirmed non-carrier child) blood (1ml EDTA or DNA)

Testing must be arranged in advance, through your local Clinical Genetics department or Fetal Medicine Unit. A completed Genetic test request form should accompany all samples. The test request form can be found here.

Please note that this new service is not currently accredited to the ISO 15189:2012 standard under our existing UKAS scope (UKAS accredited medical laboratory No. 7883). This will be submitted as an extension to scope at the earliest opportunity. Samples for R311 were previously exported to Central and South Genomic Laboratory Hub led by Birmingham Women’s and Children NHS Foundation Trust.