{Reference Type}: Case Reports
{Title}: Case report: IKZF1-related early-onset CID is expected to be missed in TREC-based SCID screening but can be identified by determination of KREC levels.
{Author}: Äng C;Zetterström RH;Ramme K;Axelsen E;Marits P;Sundin M;
{Journal}: Front Immunol
{Volume}: 14
{Issue}: 0
{Year}: 2023
{Factor}: 8.786
{DOI}: 10.3389/fimmu.2023.1257581
{Abstract}: This report illustrates a case that would have been missed in the most common screening algorithms used worldwide in newborn screening (NBS) for severe combined immunodeficiency (SCID). Our patient presented with a clinical picture that suggested a severe inborn error of immunity (IEI). The 6-month-old baby had normal T-cell receptor excision circle (TREC) levels but no measurable level of kappa-deleting recombination excision circles (KRECs) in the NBS sample. A de novo IKZF1-mutation (c.476A>G, p.Asn159Ser) was found. The clinical picture, immunologic workup, and genetic result were consistent with IKZF1-related combined immunodeficiency (CID). Our patient had symptomatic treatment and underwent allogeneic hematopoietic cell transplantation (HCT). IKZF1-related CID is a rare, serious, and early-onset disease; this case provides further insights into the phenotype, including KREC status.