SCID and Other Inborn Errors of Immunity with Low TRECs - the Brazilian Experience

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

Severe combined immunodeficiency diagnosis and genetic defects

Severe combined immunodeficiency (SCID) is a rare and life-threatening genetic disorder that severely impairs the immune system's ability to defend the body against infections. Often referred to as the "bubble boy" disease, SCID gained widespread recognition due to the case of David Vetter, a young boy who lived in a sterile plastic bubble to protect him from germs. SCID is typically present at birth, and it results from genetic mutations that affect the development and function of immune cells, particularly T cells and B cells. These immune cells are essential for identifying and fighting off infections caused by viruses, bacteria, and fungi. In SCID patients, the immune system is virtually non-existent, leaving them highly susceptible to recurrent, severe infections. There are several forms of SCID, with varying degrees of severity, but all share common features. Newborns with SCID often exhibit symptoms such as chronic diarrhea, thrush, skin rashes, and persistent infections that do not respond to standard treatments. Without prompt diagnosis and intervention, SCID can lead to life-threatening complications and a high risk of mortality. There are over 20 possible affected genes. Treatment options for SCID primarily involve immune reconstitution, with the most well-known approach being hematopoietic stem cell transplantation (HSCT). Alternatively, gene therapy is also available for some forms of SCID. Once treated successfully, SCID patients can lead relatively normal lives, but they may still require vigilant infection control measures and lifelong medical follow-up to manage potential complications. In conclusion, severe combined immunodeficiency is a rare but life-threatening genetic disorder that severely compromises the immune system's function, rendering affected individuals highly vulnerable to infections. Early diagnosis and appropriate treatment are fundamental. With this respect, newborn screening is progressively and dramatically improving the prognosis of SCID.

A diagnostic quandary: Rotavirus vaccine associated diarrhea

The patient is an otherwise healthy two-month-old boy who received the recommended vaccinations for his age group, which included the rotavirus pentavalent vaccine (RV5; RotaTeq) at his two-month well child visit. Three days later, he developed prolonged non-bloody diarrhea and was found to have persistently positive rotavirus antigen in his stool. Subsequent workup revealed mild defects in his functional T-cell immunocompetence. Genetic testing was obtained through the Invitae panel and was negative for hereditary forms of primary immunodeficiencies. The rotavirus antigen was found to have cleared from his stool around four months after receiving the RV5. Unfortunately, the source of the rotavirus infection was unable to be determined. The caregivers had misconceptions about the vaccine and the child's immune system function which led to refusal of any further vaccinations. Healthcare providers should strive to develop honest and respectful relationships with parents to have thoughtful dialogues regarding vaccine safety and efficacy.

Improving Access to Therapy for Patients With Inborn Errors of Immunity: A Call to Action

Breakthroughs in sequencing technology, targeted immunotherapy, and immune reconstituting treatment have increased the pool of patients with inborn errors of immunity, requiring expertise from clinical immunologists. A growing category of immunodeficiency, presenting as primary immune regulatory disorder and secondary immunodeficiency due to targeted immune therapy for cancer and autoimmunity, has added to the growing burden of patients needing access to immune-supportive therapy. The confluence of a growing population of patients needing a clinical immunologist, complex payer structures, and inadequate health care representation will exacerbate current problems with access to therapy. Patients, health care providers, researchers, public and private payers, and industry must come together to find solutions to improve access to therapy. In this article, we reviewed the major topics regarding access to therapy for patients with immunodeficiency.

[Principles of the diagnostics of inborn errors of immunity]

Inborn errors of immunity (IEI) are a heterogeneous group of nearly 500 diseases characterized by a congenital dysfunction of the immune system. The vast majority of IEIs are rare diseases but all IEIs share a cumulative prevalence of 1:1200-1:2000. In addition to a pathological susceptibility to infections, IEIs can also present with lymphoproliferative, autoimmune or autoinflammatory manifestations. There is often an overlap with classical rheumatic and inflammatory disease patterns. Therefore, a basic knowledge of the clinical presentation and the diagnostics of IEIs is also relevant for the practicing rheumatologist.