Test of Severe Combined Immunodeficiency (SCID, XLA, SMA)

Newborn screening.

Severe combined immunodeficiency (SCID) is a group of rare disorders with pathogenic mutations in different genes involved in the development and function of infection-fighting immune cells. Infants with SCID appear healthy at birth but are highly susceptible to severe infections. Infants with SCID require life-saving treatments. There are several forms of SCID including X-linked and recessive inheritance.
Spinal Muscular Atrophy (SMA) is a group of hereditary diseases that progressively destroys motor neurons. It is one of the most common lethal recessive genetic disorders, and has an incidence of approximately 1/10,000 live births, and an estimated carrier frequency of approximately 1 in 57.
Primary immunodeficiency disorder (PID), X-linked agammaglobulinemia (XLA), commonly caused by a mutation or deletion in the BTK gene which prevents the normal development of B lymphocytes and that results in a severe antibody deficiency, is being considered as a condition. Early diagnosis of PID patients facilitate early treatments, such as stem cell transplantation for SCID or immunoglobulin infusion therapy for XLA, which result in better outcomes.

Revvity has developed a multiplex real-time PCR assay to allow the screening of infants with severe forms of PID manifested by T and B cell lymphopenia and identify the absence of exon 7 in the SMN1 gene, which is present in approximately 96% of patients with SMA. The assay amplifies four targets in a single PCR reaction; T-cell receptor excision circles (TREC), as a marker of SCID, Kappa-deleting recombination excision circles (KREC), as a marker of XLA, the exon 7 of the SMN1/2 genes, and the RNase P (RPP30) gene, which is used as an internal control and to evaluate the quantity and quality of the DNA extracted from the 3.2 mm punches.