We then successfully incorporated the SMN1 exon 7 test reagents into the existing multiplex real-time PCR assay for T-cell receptor excision circle (TREC), a marker of T cell production, to detect severe combined immunodeficiency (SCID), which also included the target RPP30 as an internal control for both assays (manuscript in preparation). The gene discussed is RPP30; the disease is severe combined immunodeficiency.