Deficient T Cell Receptor Excision Circles (TRECs) in autosomal recessive hyper IgE syndrome caused by DOCK8 mutation: Implications for pathogenesis and potential detection by newborn screening

Loss of function of DOCK8 is the major cause of autosomal recessive hyper IgE syndrome, a primary immunodeficiency with adaptive and innate immune dysfunction. Patients affected with ARHIES have atopic dermatitis and recurrent, potentially life-threatening viral and bacterial infections. Three consanguineous Pakistani siblings presented with severe atopic dermatitis and superinfection. Direct sequencing of DOCK8 in all three affected siblings demonstrated homozygosity for a deleterious, novel exon 14 frame shift mutation. Current newborn screening for severe combined immunodeficiency syndrome (SCID) and related T cell disorders relies on the quantitation of T Cell Receptor Excision Cells (TRECs) in dried blood spots (DBS). Significantly, both older affected siblings had undetectable TRECs, and TREC copy number was reduced in the youngest sibling. These findings suggest that AR-HIES may be detected by TREC newborn screening, and this diagnosis should be considered in the evaluation of newborns with abnormal TRECs who do not have typical SCID.

► AR-HIES is a form of severe combined immunodeficiency.
► Low to undetectable TRECs were found in three siblings with DOCK deficient AR-HIES.
► SCID is a disorder of high priority for population-based newborn screening.
► DOCK8 deficient AR-HIES may be amenable to newborn screening through TRECs analysis.