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We present a case study of a young male with a history of 22q11.2 deletion syndrome (22qDS), diagnosed with systemic capillary leak syndrome (SCLS) who presented with acute onset of diffuse anasarca and sub-comatose obtundation. We hypothesized that his co-presentation of neurological sequelae might be due to blood-brain barrier (BBB) susceptibility conferred by the 22q11.2 deletion, a phenotype that we have previously identified in 22qDS. Using pre- and post-intravenous immunoglobulins (IVIG) patient serum, we studied circulating biomarkers of inflammation and assessed the potential susceptibility of the 22qDS BBB. We employed in vitro cultures of differentiated BBB-like endothelial cells derived from a 22qDS patient and a healthy control. We found evidence of peripheral inflammation and increased serum lipopolysaccharide (LPS) alongside endothelial cells in circulation. We report that the patient's serum significantly impairs barrier function of the 22qDS BBB compared to control. Only two other cases of pediatric SCLS with neurologic symptoms have been reported, and genetic risk factors have been suggested in both instances. As the third case to be reported, our findings are consistent with the hypothesis that genetic susceptibility of the BBB conferred by genes such as claudin-5 deleted in the 22q11.2 region promoted neurologic involvement during SCLS in this patient., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: Duplication of chromosome 22q11.2 due to meiotic non-allelic homologous recombination results in a distinct syndrome, chromosome 22q11.2 duplication syndrome that has some overlapping phenotypic features with the corresponding 22q11.2 deletion syndrome. Literature on immunologic aspects of the duplication syndrome is limited. We conducted a retrospective study of 216 patients with this syndrome to better define the key features of the duplication syndrome., Methods: Single-center retrospective record review was performed. Data regarding demographics, clinical details, and immunological tests were compiled, extracted into a predetermined data collection form, and analyzed., Results: This cohort comprised 113 (52.3%) males and 103 (47.7%) females. The majority (54.6%) of mapped duplications were between low copy repeat regions A-D (LCR22A to -D). Though T cell subsets were relatively preserved, switched memory B cells, immunoglobulins, and specific antibodies were each found to be decreased in a subset of the cohort. One-fifth (17/79, 21.5%) of patients had at least 2 low immunoglobulin values, and panhypogammaglobulinemia was found in 11.7% (9/79) cases. Four children were on regular immunoglobulin replacement therapy. Asthma and eczema were the predominant atopic symptoms in our cohort., Conclusion: Significant immunodeficiencies were observed in our cohort, particularly in B cells and antibodies. Our study expands the current clinical understanding and emphasizes the need of immunological studies and multidisciplinary approaches for these patients., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS) is a combined immunodeficiency caused by gain-of-function mutations in the C-X-C chemokine receptor type 4 (CXCR4) gene. We characterize a unique international cohort of 66 patients, including 57 (86%) cases previously unreported, with variable clinical phenotypes. Of 17 distinct CXCR4 genetic variants within our cohort, 11 were novel pathogenic variants affecting 15 individuals (23%). All variants affect the same CXCR4 region and impair CXCR4 internalization resulting in hyperactive signaling. The median age of diagnosis in our cohort (5.5 years) indicates WHIM syndrome can commonly present in childhood, although some patients are not diagnosed until adulthood. The prevalence and mean age of recognition and/or onset of clinical manifestations within our cohort were infections 88%/1.6 years, neutropenia 98%/3.8 years, lymphopenia 88%/5.0 years, and warts 40%/12.1 years. However, we report greater prevalence and variety of autoimmune complications of WHIM syndrome (21.2%) than reported previously. Patients with versus without family history of WHIM syndrome were diagnosed earlier (22%, average age 1.3 years versus 78%, average age 5 years, respectively). Patients with a family history of WHIM syndrome also received earlier treatment, experienced less hospitalization, and had less end-organ damage. This observation reinforces previous reports that early treatment for WHIM syndrome improves outcomes. Only one patient died; death was attributed to complications of hematopoietic stem cell transplantation. The variable expressivity of WHIM syndrome in pediatric patients delays their diagnosis and therapy. Early-onset bacterial infections with severe neutropenia and/or lymphopenia should prompt genetic testing for WHIM syndrome, even in the absence of warts., (© 2022. The Author(s).)

Purpose: Chromosome 22q11.2 deletion syndrome (22q11.2DS), the most common cause of DiGeorge syndrome, is quite variable. Neonatal diagnosis traditionally relies on recognition of classic features and cytogenetic testing, but many patients come to attention only following identification of later onset conditions, such as hypernasal speech due to palatal insufficiency and developmental and behavioral differences including speech delay, autism, and learning disabilities that would benefit from early interventions. Newborn screening (NBS) for severe combined immunodeficiency (SCID) is now identifying infants with 22q11.2DS due to T cell lymphopenia. Here, we report findings in such neonates, underscoring the efficacy of early diagnosis., Methods: A retrospective chart review of 1350 patients with 22q11.2DS evaluated at the Children's Hospital of Philadelphia identified 11 newborns with a positive NBS for SCID., Results: Five out of 11 would have been diagnosed with 22q11.2DS without NBS, whereas early identification of 22q11.2DS in 6/11 led to the diagnosis of significant associated features including hypocalcemia, congenital heart disease (CHD), and gastroesophageal reflux disease that may have gone unrecognized and therefore untreated., Conclusions: Our findings support rapidly screening infants with a positive NBS for SCID, but without SCID, for 22q11.2DS even when typically associated features such as CHD are absent, particularly when B cells and NK cells are normal. Moreover, direct NBS for 22q11.2DS using multiplex qPCR would be equally, if not more, beneficial, as early identification of 22q11.2DS will obviate a protracted diagnostic odyssey while providing an opportunity for timely assessment and interventions as needed, even in the absence of T cell lymphopenia.

Newborn screening for SCID has revealed the association of low T cells with a number of unexpected syndromes associated with low T cells, some of which were not appreciated to have this feature. This review will discuss diagnostic approaches and the features of some of the syndromes likely to be encountered following newborn screening for immune deficiencies.