PMC5513981_01
CD3+ and CD4+ cell counts in progressive lymphopenia of two siblings with low T-cell receptor excision circles on newborn screening. Red lines delimit the normal range for age.
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F1
At 17 months, his CD4+ T-cell counts dropped below 300 cells/muL (Figure 1), and he started Bactrim for Pneumocystis jiroveci pneumonia (PJP) prophylaxis. His immunologic evaluation also revealed normal immunoglobulin levels, normal NK cell counts, normal lymphocyte responses to mitogens and antigens, and decreased T-cell counts, albeit less severe than his brother (Table 1; Figure 1).