SCIDS

The Artemis protein (also known as DNA cross-link repair enzyme 1C, DCLRE1C) was first characterized as a part of the VDJ-recombination process in 2001 in a study of patients with radiosensitive SCID [2].

The use of advanced genetic methods in diagnosis of primary immunodeficiencies has shown us that the spectrum of diseases associated with SCID genes is both wide and variable.

The genetic variant has previously been reported as disease-causing in a patient from a patient cohort with radiosensitive SCID and Omenn syndrome [12].

Mutations in the Artemis/DCLRE1C gene have traditionally been associated with SCID and Omenn syndrome, but recently various mutations have been shown to be associated also with milder forms of immunodeficiencies, including hypogammaglobulinemia [3, 4].

There are several types of SCIDS. Deficiency of the common gamma chain of the T-cell receptor is the most common, affecting nearly 45% of all cases.

Infants with this type of SCIDS have the lowest total lymphocyte counts of all, and the T-, Band NK-lymphocyte counts are all very low.

Another, less common SCIDS type is deficiency of the alpha chain of the IL-7 receptor, in which the infant has B and NK cells, but no T cells.

The screening test for SCID and other causes of T cell lymphopenia is performed on dried blood spots, just as all other RUSP tests are.

The experience to date has shown that the TREC assay has detected a number of other conditions in addition to typical and leaky SCID and Omenn's syndrome (an SCID variant).

If there are CD3 positive T cells present in the screen-positive newborn, there is a possibility they could be maternal, because maternal T cells enter the fetal circulation during pregnancy and, if the fetus has SCID, he or she would not be able to reject the mother's T cells.