X-linked agammaglobulinemia (XLA) is a rare disorder associated with defective B-lymphocyte differentiation, also known as circulating B-cell deletion or deficiency, reduced levels of all serum immunoglobulin isoforms, and a lack of specific antibody production. XLA has rare neurological complications but has a refractory course and poor prognosis. Here, we report a case of XLA due to a Bruton tyrosine kinase gene variant with progressive neurodegeneration. We describe a boy with XLA who had recurrent infections since infancy and, after diagnosis was confirmed by genetic testing, was started on regular intravenous immunoglobulin at the age of 5 years. However, after a second episode of suspected meningitis at the age of 4.9 years, he developed motor and cognitive deterioration, becoming unable to sit, walk, eat or speak after 8 months, with frequent tremors and multiple seizures, and died of respiratory failure at the age of 7 years. Magnetic resonance imaging showed progressive whole brain atrophy. Combined with a mild lymphocytic inflammation of the cerebrospinal fluid, we suspected a chronic active infection of the central nervous system, but it was difficult to confirm our suspicion by serological testing due to the inability to produce neutralizing antibodies. Severe progressive neurodegeneration in XLA is rare. With this case we would like to discuss the difficulties in diagnosing infection in patients with XLA and the role of autoimmune mechanisms in the development of neurodegeneration.

Coronin-1A deficiency, caused by mutations in the CORO1A gene, is an autosomal recessive immunodeficiency characterized by T-cell dysfunction and is classified as severe combined immunodeficiency (SCID). This condition presents with lymphopenia, hypogammaglobulinemia, recurrent Epstein-Barr virus (EBV) infections, EBV-associated B-cell lymphoma and epidermodysplasia verruciformis. This case report presents a 32-year-old female with Coronin-1A deficiency, who developed IgM-dominant membranoproliferative glomerulonephritis (MPGN) alongside recurrent viral infections. This is the first reported case linking Coronin-1A deficiency with MPGN. The patient was treated with corticosteroids, which improved her renal function, but she succumbed to recurrent infections within a year. This case emphasizes the potential for renal disease in immunodeficient patients with persistent infections.

The aim of the present study was to investigate the clinical spectrum of IgG subclass deficiencies (IgGSDs) and assess the relative clinical significance of diagnosing each specific IgGSD disorder as compared to the common variable immunodeficiency (CVID). The clinical spectrum and immunological findings from 96 patients, diagnosed with diverse IgGSDs, were retrospectively evaluated. Specific IgGSDs were compared with each other and a cohort of 270 patients with CVID. In comparison to CVID, recurrent lower respiratory tract infections (LRTIs) and bronchiectasis were rarer in IgGSDs, while recurrent mucocutaneous herpes simplex virus reactivations were more common. With respect to autoimmunity, IgGSDs were associated with arthritis, while autoimmune cytopenias were less frequently observed than in CVID. Among IgGSDs, herpes zoster was more common in IgG3SD. Arthritis was more prevalent in IgG1 + 3SD. Given its association with LRTI, splenomegaly, immune thrombocytopenic purpura, and the lower class-switched memory B-cell counts, IgG2 + 4SD is the IgGSD that rather resembles CVID. Comparative evaluation of phenotypes and treatments of patients with IgGSDs and CVID reveals distinct features, suggesting the differential clinical significance of diagnosing IgGSDs. The differential clinical expressions of IgGSDs highlight the need for studying each IgGSD separately in order to optimize disorder-specific follow-up procedures and prophylactic anti-infective measures.

Selective IgM deficiency is a rare immunological disorder, with patients presenting with recurrent infections and allergic manifestations. However, the association with early postoperative infection has not been widely reported in the literature. We describe a rare case of a patient who had an early wound infection 1 day after excision of a Merkel cell carcinoma from his right buttock and was later found to have decreased IgM levels. Selective IgM deficiency should therefore be considered in patients presenting with recurrent infections or in patients who have previously undergone surgery and subsequently developed early infection postoperatively. In this subset of patients, extra precautions may need to be taken pre- and postoperatively to reduce the risk of developing a postoperative infection.

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive disease associated with a highly variable clinical presentation, including systemic vasculitis, immunodeficiency, and cytopenia. We report a case of a 16-year-old girl affected by recurrent viral infections [including cytomegalovirus (CMV)-related hepatitis and measles vaccine virus-associated manifestations] and persistent inflammation, which occurred after Parvovirus infection and complicated by secondary hemophagocytic lymphohistiocytosis (HLH). HLH's first episode presented at 6 years of age and was preceded by persistent fever and arthralgia with evidence of Parvovirus B19 infection. The episode responded to intravenous steroids but relapsed during steroids tapering. High-dose intravenous immunoglobulin (IVIG) helped manage her clinical symptoms and systemic inflammation. The frequency of IVIG administration and the dosage were progressively reduced. At the age of 9, she experienced varicella zoster virus (VZV) reactivation followed by the recurrence of the inflammatory phenotype complicated by HLH with neurological involvement. Again, high-dose steroids and monthly IVIG resulted in a quick response. Targeted next-generation sequencing (NGS) for autoinflammatory diseases and immunodeficiencies revealed the homozygous Leu183Pro ADA2 mutation, which was confirmed by Sanger analysis. ADA2 enzymatic test showed a complete loss of ADA2 activity. For about 3 years, IVIG alone was completely effective in preventing flares of inflammation and neurological manifestations. Anti-TNF treatment was started at the age of 13 for the appearance of recurrent genital ulcers, with a complete response. This case further expands the clinical spectrum of DADA2 and emphasizes the importance of extensive genetic testing in clinical phenotypes characterized by persistent unspecific inflammatory syndromes. The use of high doses of IVIG might represent a possible effective immune modulator, especially in combination with anti-TNF treatment.