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Neonatal Lymphopenia Screening Is Important for Early Diagnosis of Severe Combined Immunodeficiency
Aykut Poyraz1, Murat Cansever2, Ipek Muderris3
1Department of Pediatrics, Erciyes University, School of Medicine, Kayseri, Turkey.
Insights
Screening newborns for severe combined immunodeficiency (SCID) using complete blood count to detect absolute lymphopenia is a simpler, more affordable method than T-cell receptor excision circles. This approach can improve early detection of SCID in developing countries.
Area of Science:
- Immunology
- Pediatrics
- Genetics
Background:
- Neonatal screening for severe combined immunodeficiency (SCID) is crucial for early intervention.
- T-cell receptor (TCR) excision circles (TRECs) are a current but expensive screening method, particularly for developing nations.
- Lymphopenia, a low lymphocyte count, can be an indicator of underlying immunodeficiencies like SCID.
Purpose of the Study:
- To evaluate the effectiveness of absolute lymphopenia detection via complete blood count (CBC) as a screening tool for SCID in newborns.
- To propose a more accessible and cost-effective screening strategy for SCID in resource-limited settings.
- To enhance clinician awareness of lymphopenia as a potential indicator of SCID.
Main Methods:
- A prospective study involving 2,000 newborns.
- Complete blood count (CBC) was performed on umbilical cord blood samples.
- Absolute lymphopenia was defined as an absolute lymphocyte count <3,000/mm³; CBC was repeated at 1 month for affected infants.
Main Results:
- Absolute lymphopenia was identified in 42 newborns (2.1%).
- Two infants presented with persistent lymphopenia and were diagnosed with SCID (one with a RAG1 defect, the other with a JAK3 defect).
- Both SCID-diagnosed infants successfully underwent hematopoietic stem cell transplantation.
Conclusions:
- Absolute lymphopenia screening using CBC is a simpler, less invasive, and more economical method for detecting SCID in newborns compared to TREC analysis.
- This CBC-based approach holds significant potential for widespread SCID screening in developing countries.
- The study highlights the importance of recognizing lymphopenia in neonates for timely SCID diagnosis and treatment.
Objective:
T-cell receptor excision circles are expensive for neonatal severe combined immunodeficiency screening in developing countries. We aimed to detect immunodeficiencies presenting with lymphopenia to enable screening in the general population and to improve awareness regarding lymphopenia among clinicians.
Study Design:
This study was conducted prospectively. In all newborns included, complete blood count from umbilical cord blood samples was recorded. Absolute lymphopenia was defined as absolute lymphocyte count <3,000/mm3 in umbilical cord blood sample. Complete blood count was repeated at month 1 in cases found to have lymphopenia.
Results:
Overall, 2,000 newborns were included in the study. Absolute lymphopenia was detected in 42 newborns (2.1%), while lymphocyte count was >3,000/mm3 in 1,958 newborns (97.9%). Two infants with persisted lymphopenia at the end of the first month; therefore, further evaluations such as lymphocyte subsets for severe combined immunodeficiency (SCID) were done. In the first infant, the lymphocyte subgroups were detected as compatible with T (-), B (-), natural killer cells (NK) (+) SCID phenotype RAG defect. Sanger sequencing revealed that NM_000448 c.2209C > T (p.R737C) homozygous mutation of RAG1 gene. In the other infant, the lymphocyte subgroups were found as considered with T (-), B (+) NK (-) SCID phenotype JAK3 defect. Both patients underwent hematopoietic stem cell transplantation from human leukocyte antigen-matched family member.
Conclusion:
Absolute lymphopenia by complete blood count is a more simpler, relatively noninvasive and inexpensive screening methodfor detection of SCID in newborns compared with T-cell receptor excision circles technique.
Key Points:
· Our study was conducted with a much smaller number of study groups compared with the previous ones.. · However, SCID was found at a higher rate compared with other studies.. · Our study for this disease that is common in our country where consanguineous marriages are common.
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