Abstract
Severe combined immunodeficiency (SCID) is a heterogeneous genetic disease characterized by severe T-cell lymphopenia with a profound impairment of T- and B-cells' function and, in some types, also NK cells. Hematopoietic cell transplantation (HCT) is the only curative treatment currently available in Brazil. Late diagnosis and treatment are the main factors affecting the survival of these children. This study aims to describe the demographic, phenotypic, genotypic, and clinical characteristics of twenty SCID patients (including typical SCID, leaky-SCID, and Omenn Syndrome) followed at a Brazilian referral center and correlate these data with their clinical outcome. The children were analyzed into two groups: patients diagnosed early by newborn screening (NBS) or family history, n = 7, and patients with late diagnosis, by clinical presentation, n = 13. The 2-year overall survival (OS) of the late group was 29.2%, in contrast to the 2-year OS of the early diagnosis group of 71.4% (p = 0.053). However, despite early diagnosis in the first group, timely access to HCT was delayed, with a median of 11 months. This research reveals that survival depends not only on timely diagnosis but also on early definitive treatment. To improve SCID survival rates, developing countries need public policies that allow rapid access to curative treatment for these patients.