Expanded Newborn Screening
1. Disease Overview
- Severe Combined Immunodeficiency (SCID)
Severe Combined Immunodeficiency (SCID) refers to a group of disorders characterized by the profound deficiency of both humoral and cellular immunity. Infants with SCID typically die from infections before the age of two if left untreated. The hallmark of SCID is a severe defect in the production and function of T lymphocytes, often accompanied by a defect in B lymphocytes, either as a primary or secondary issue. In certain genetic subtypes, there may also be a deficiency in natural killer (NK) cells. The term “combined” reflects the impairment of both T and B lymphocytes in this condition.
Estimated incidence: Approximately 1 in 50,000 to 100,000 live births.
- X-linked Agammaglobulinemia (XLA)
X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disorder, and among those involving B-cell dysfunction, it is the most common. It is typically caused by mutations or deletions in the BTK gene, which halts the maturation of B cells. As a result, few or no B cells are produced, leading to a severe deficiency of antibodies in affected children. Since the BTK gene is located on the X chromosome, only boys are affected.
Estimated incidence: Approximately 1 in 250,000 live male births.
- Spinal Muscular Atrophy (SMA)
Spinal Muscular Atrophy (SMA) is a rare genetic disease that affects motor neurons in the spinal cord—cells responsible for controlling muscle movement. When these neurons are damaged or lost, the muscles progressively weaken and atrophy, making movement, swallowing, and breathing increasingly difficult. SMA is caused by mutations in the SMN1 (Survival Motor Neuron 1) gene, which reduce the production of a protein essential for motor neuron survival. The disease follows an autosomal recessive inheritance pattern, meaning both parents must carry the defective gene for their child to be at risk.
Estimated incidence: Approximately 1 in 10,000 live births.
Carrier frequency in the general population: Around 1 in 54 individuals.
2. Revvity’s Screening Solution for SCID, SMA, and XLA
- Product name: Eonis™ SCID-SMA Kit
- Product code: 3241-0020
- Manufacturer: Wallac Oy – Finland
- Packaging: 384 tests
- Application:
This kit is used for the semi-quantitative detection of T-cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC), as well as the qualitative detection of exon 7 of the SMN1 gene and the RPP30 gene from DNA extracted from dried blood spot (DBS) samples. It supports newborn screening for Severe Combined Immunodeficiency (SCID), X-linked Agammaglobulinemia (XLA), and Spinal Muscular Atrophy (SMA).
The Eonis™ SCID-SMA Kit is a multiplex real-time PCR assay. It uses target-specific primers and hydrolysis probes to amplify and detect four targets: TREC, KREC, SMN1 exon 7, and RPP30. DNA is extracted from a single newborn dried blood spot and amplified in one PCR reaction. All PCR reagents are pre-dried on the PCR plate.
3. Required Equipment
- The Eonis™ Q 96-well variant instrument
- DBS Puncher Instrument or Panthera Puncher™ 9 Instrument
- TriNEST™ Incubator shaker instrument
