Background: CD40 ligand (CD40L) deficiency, an X-linked primary immunodeficiency, causes recurrent sinopulmonary, Pneumocystis and Cryptosporidium species infections. Long-term survival with supportive therapy is poor. Currently, the only curative treatment is hematopoietic stem cell transplantation (HSCT). Objective: We performed an international collaborative study to improve patients' management, aiming to individualize risk factors and determine optimal HSCT characteristics. Methods: We retrospectively collected data on 130 patients who underwent HSCT for CD40L deficiency between 1993-2015. We analyzed outcome and variables' relevance with respect to survival and cure. Results: Overall survival (OS), event-free survival (EFS), and disease-free survival (DFS) were 78.2%, 58.1%, and 72.3% 5 years after HSCT. Results were better in transplantations performed in 2000 or later and in children less than 10 years old at the time of HSCT. Pre-existing organ damage negatively influenced outcome. Sclerosing cholangitis was the most important risk factor. After 2000, superior OS was achieved with matched donors. Use of myeloablative regimens and HSCT at 2 years or less from diagnosis associated with higher OS and DFS. EFS was best with matched sibling donors, myeloablative conditioning (MAC), and bone marrow-derived stem cells. Most rejections occurred after reduced-intensity or nonmyeloablative conditioning, which associated with poor donor cell engraftment. Mortality occurred mainly early after HSCT, predominantly from infections. Among survivors who ceased immunoglobulin replacement, T-lymphocyte chimerism was 50% or greater donor in 85.2%. Conclusion: HSCT is curative in patients with CD40L deficiency, with improved outcome if performed before organ damage development. MAC is associated with better OS, EFS, and DFS. Prospective studies are required to compare the risks of HSCT with those of lifelong supportive therapy.

Hearing loss in patients with X-linked agammaglobulinemia is often attributed to recurrent infections. However, recent genetic studies suggest a different etiology in some patients. We present three unrelated patients, 6, 9, and 14 years of age, with large deletions of the terminal portion of the Bruton tyrosine kinase (Btk) gene extending 4.2-19 kb beyond the 3' end of the gene. The DNA immediately downstream of the 3' end of Btk contains the deafness-dystonia protein gene (DDP). Mutations in this gene have recently been shown to underlie the Mohr-Tranebjaerg syndrome, which is characterized by sensorineural deafness, dystonia, and mental deficiency. Besides the immunodeficiency, our patients exhibited progressive sensorineural deafness. The clue to an associated hearing problem was delayed development of speech in one patient and post-lingual deafness noticed between the age of 3-4 years in the other two. These patients have not yet exhibited significant associated neurologic deficits.

Isolated congenital asplenia (ICA) is the only known human developmental defect exclusively affecting a lymphoid organ. In 2013, we showed that private deleterious mutations in the protein-coding region of , encoding ribosomal protein SA, caused ICA by haploinsufficiency with complete penetrance. We reported seven heterozygous protein-coding mutations in 8 of the 23 kindreds studied, including 6 of the 8 multiplex kindreds. We have since enrolled 33 new kindreds, 5 of which are multiplex. We describe here 11 new heterozygous ICA-causing protein-coding mutations, and the first two mutations in the 5'-UTR of this gene, which disrupt mRNA splicing. Overall, 40 of the 73 ICA patients (55%) and 23 of the 56 kindreds (41%) carry mutations located in translated or untranslated exons of Eleven of the 43 kindreds affected by sporadic disease (26%) carry mutations, whereas 12 of the 13 multiplex kindreds (92%) carry mutations. We also report that 6 of 18 (33%) protein-coding mutations and the two (100%) 5'-UTR mutations display incomplete penetrance. Three mutations were identified in two independent kindreds, due to a hotspot or a founder effect. Finally, RPSA ICA-causing mutations were demonstrated to be de novo in 7 of the 23 probands. Mutations in exons can affect the translated or untranslated regions and can underlie ICA with complete or incomplete penetrance.

Chronic granulomatous disease is an inherited disorder in which phagocytes lack a functional NADPH oxidase and cannot produce superoxide anions. The most common form is caused by mutations in CYBB encoding gp91phox. We investigated 24 CGD patients and their families. Twenty-one mutations in CYBB were classified as X91(0), X91(+) or X91(-) variants according to cytochrome b (558) expression. Point mutations in encoding regions represented 50 % of the mutations found in CYBB, splice site mutations 27 %, deletions and insertions 23 %. Eight mutations in CYBB were novel leading to X91(0)CGD cases. Two of these were point mutations: c493G>T and a double mutation c625C>G in exon 6 and c1510C>T in exon 12 leading to a premature stop codon at Gly165 in gp91phox and missense mutations His209Arg/Thr503Ile respectively. Two novel splice mutations in 5'intronic regions of introns 1 and 6 were found. A novel deletion/insertion c1024_1026delCTG/insT results in a frameshift introducing a stop codon at position 346 in gp91phox. The last novel mutation was the insertion of a T at c1373 leading to a frameshift and a premature stop codon at position 484 in gp91phox. For the first time the precise size of two large mutations in CYBB was determined by array-comparative genomic hybridization and carriers' status were evaluated by multiplex ligation-dependent probe amplification assay. No clear correlation between clinical severity and CYBB mutations could be established. Of three mutations in CYBA, NCF1 and NCF2 leading to rare autosomal recessive CGD, one nonsense mutation c29G>A in exon 1 of NCF2 was new.

Background Due to the absence of curative treatments for inborn errors of immunity (IEI), children born with IEI require long-term follow-up for disease manifestations and related complications that occur over the lifespan. Effective transition from pediatric to adult services is known to significantly improve adherence to treatment and long-term outcomes. It is currently not known what transition services are available for young people with IEI in Europe. Objective To understand the prevalence and practice of transition services in Europe for young people with IEI, encompassing both primary immunodeficiencies (PID) and systemic autoinflammatory disorders (AID). Methods A survey was generated by the European Reference Network on immunodeficiency, autoinflammatory, and autoimmune diseases Transition Working Group and electronically circulated, through professional networks, to pediatric centers across Europe looking after children with IEI. Results Seventy-six responses were received from 52 centers, in 45 cities across 17 different countries. All services transitioned patients to adult services, mainly to specialist PID or AID centers, typically transferring up to ten patients to adult care each year. The transition process started at a median age of 16–18 years with transfer to the adult center occurring at a median age of 18–20 years. 75% of PID and 68% of AID centers held at least one joint appointment with pediatric and adult services prior to the transfer of care. Approximately 75% of PID and AID services reported having a defined transition process, but few centers reported national disease-specific transition guidelines to refer to. Conclusions Transition services for children with IEI in Europe are available in many countries but lack standardized guidelines to promote best practice.