Objective:

To describe four clinical cases of inborn errors of immunity (IEI) in Low German Mennonite (LGM) patients in Mexico and contextualize these findings within a comprehensive literature review of previously reported IEI cases in this population.

Approach:

• Study Design: A retrospective case series conducted at two tertiary pediatric referral centers in Mexico between 2020 and 2025.
• Data Collection: Clinical, immunological, and genetic data were extracted from medical records, and genetic diagnoses were established using next-generation sequencing or whole-exome sequencing.
• Literature Review: A narrative literature search was performed in PubMed, Embase, SciELO, and Web of Science to identify previously reported IEI cases in LGM populations.

Key Findings:

• Four patients with distinct IEI were identified: one with G6PC3 deficiency, one with XLA due to a pathogenic variant in the BTK gene, and two with SCID.
• All patients required disease-specific therapy, including granulocyte colony-stimulating factor, immunoglobulin replacement, and/or hematopoietic cell transplantation.
• The literature review identified a broad spectrum of IEI in LGM populations, including cellular and humoral immunodeficiencies, phagocyte disorders, DNA repair defects, autoinflammatory conditions, and bone marrow failure syndromes.

Interpretation:

This exploratory case series contributes to the evidence on IEI in LGM populations.

Limitations:

• Small sample size.
• Retrospective design limits generalizability.

Conclusion:

Early diagnosis through newborn screening and accessible genetic testing remains essential to improve outcomes.