An International Survey of Allogeneic Hematopoietic Cell Transplantation for X-Linked Agammaglobulinemia.

PURPOSE: X-linked agammaglobulinemia (XLA) is an inborn error of immunity caused by variants in Bruton's tyrosine kinase (BTK). XLA patients require lifelong immunoglobulin replacement therapy (IgRT). Only few XLA patients are indicated for allogeneic hematopoietic cell transplantation (HCT) because of severe complications. Accordingly, the published transplantation experience in XLA is minimal. We aimed to collect clinical data of XLA patients who received HCT in an international framework and to establish appropriate transplantation criteria and methods for XLA patients. METHODS: XLA patients were recruited through a questionnaire and a literature review. The data are on patient characteristics and transplantation methods and outcomes. RESULTS: In this study, twenty-two XLA patients who underwent HCT were recruited. The indication for HCT was recurrent or life-threatening infection in sixteen patients, malignancy in three, and other factors in three. A myeloablative conditioning, reduced toxicity myeloablative conditioning (RT-MAC), and reduced intensity conditioning (RIC) were selected in four, ten, and eight patients, respectively. Engraftment was achieved in 21 patients (95%). In all patients, 2-year overall survival (OS) and event-free survival (EFS) were 86% and 77%, respectively. In patients who received RT-MAC or RIC using treosulfan, busulfan, or melphalan, 2-year OS and EFS were 82% and 71%, respectively. Finally, twenty-one patients (95%) obtained complete or stable high-level mixed chimerism (50-95%), and the 1-year discontinuation rate of IgRT was 89%. CONCLUSION: Based on the concept in which IgRT is the standard treatment for XLA, HCT may be an effective and safe alternative treatment option for XLA patients, and IgRT can be discontinued following transplantation. It is ideal to perform HCT in XLA patients for whom transplantation is indicated before they develop organ damage.

Reduced-Intensity/Reduced-Toxicity Conditioning Approaches Are Tolerated in XIAP Deficiency but Patients Fare Poorly with Acute GVHD.

X-linked inhibitor of apoptosis (XIAP) deficiency is an inherited primary immunodeficiency characterized by chronic inflammasome overactivity and associated with hemophagocytic lymphohistiocytosis (HLH) and inflammatory bowel disease (IBD). Allogeneic hematopoietic cell transplantation (HCT) with fully myeloablative conditioning may be curative but has been associated with poor outcomes. Reports of reduced-intensity conditioning (RIC) and reduced-toxicity conditioning (RTC) regimens suggest these approaches are well tolerated, but outcomes are not well established. Retrospective data were collected from an international cohort of 40 patients with XIAP deficiency who underwent HCT with RIC or RTC. Thirty-three (83%) patients had a history of HLH, and thirteen (33%) patients had IBD. Median age at HCT was 6.5 years. Grafts were from HLA-matched (n = 30, 75%) and HLA-mismatched (n = 10, 25%) donors. There were no cases of primary graft failure. Two (5%) patients experienced secondary graft failure, and three (8%) patients ultimately received a second HCT. Nine (23%) patients developed grade II-IV acute GVHD, and 3 (8%) developed extensive chronic GVHD. The estimated 2-year overall and event-free survival rates were 74% (CI 55-86%) and 64% (CI 46-77%), respectively. Recipient and donor HLA mismatch and grade II-IV acute GVHD were negatively associated with survival on multivariate analysis with hazard ratios of 5.8 (CI 1.5-23.3, p = 0.01) and 8.2 (CI 2.1-32.7, p < 0.01), respectively. These data suggest that XIAP patients tolerate RIC and RTC with survival rates similar to HCT of other genetic HLH disorders. Every effort should be made to prevent acute GVHD in XIAP-deficient patients who undergo allogeneic HCT.

Fine Breakpoint Mapping by Genome Sequencing Reveals the First Large X Inversion Disrupting the NHS Gene in a Patient with Syndromic Cataracts.

Inversions are structural variants that are generally balanced. However, they could lead to gene disruptions or have positional effects leading to diseases. Mutations in the NHS gene cause Nance-Horan syndrome, an X-linked disorder characterised by congenital cataracts and dental anomalies. Here, we aimed to characterise a balanced pericentric inversion X(p22q27), maternally inherited, in a child with syndromic bilateral cataracts by breakpoint mapping using whole-genome sequencing (WGS). 30× Illumina paired-end WGS was performed in the proband, and breakpoints were confirmed by Sanger sequencing. EdU assays and FISH analysis were used to assess skewed X-inactivation patterns. RNA expression of involved genes in the breakpoint boundaries was evaluated by droplet-digital PCR. We defined the breakpoint position of the inversion at Xp22.13, with a 15 bp deletion, disrupting the unusually large intron 1 of the canonical NHS isoform, and also perturbing topologically-associated domains (TADs). Moreover, a microhomology region of 5 bp was found on both sides. RNA analysis confirmed null and reduced NHS expression in the proband and his unaffected mother, respectively. In conclusion, we report the first chromosomal inversion disrupting NHS, fine-mapped by WGS. Our data expand the clinical spectrum and the pathogenic mechanisms underlying the NHS defects.

Immune function in X-linked retinoschisis subjects in an AAV8-RS1 phase I/IIa gene therapy trial.

This study explored systemic immune changes in 11 subjects with X-linked retinoschisis (XLRS) in a phase I/IIa adeno-associated virus 8 (AAV8)-RS1 gene therapy trial (ClinicalTrials.gov: NCT02317887). Immune cell proportions and serum analytes were compared to 12 healthy male controls. At pre-dosing baseline the mean CD4/CD8 ratio of XLRS subjects was elevated. CD11c+ myeloid dendritic cells (DCs) and the serum epidermal growth factor (EGF) level were decreased, while CD123+ plasmacytoid DCs and serum interferon (IFN)-γ and tumor necrosis factor (TNF)-α were increased, indicating that the XLRS baseline immune status differs from that of controls. XLRS samples 14 days after AAV8-RS1 administration were compared with the XLRS baseline. Frequency of CD11b+CD11c+ DCc was decreased in 8 of 11 XLRS subjects across all vector doses (1e9-3e11 vector genomes [vg]/eye). CD8+human leukocyte antigen-DR isotype (HLA-DR)+ cytotoxic T cells and CD68+CD80+ macrophages were upregulated in 10 of 11 XLRS subjects, along with increased serum granzyme B in 8 of 11 XLRS subjects and elevated IFN-γ in 9 of 11 XLRS subjects. The six XLRS subjects with ocular inflammation after vector application gave a modestly positive correlation of inflammation score to their respective baseline CD4/CD8 ratios. This exploratory study indicates that XLRS subjects may exhibit a proinflammatory, baseline immune phenotype, and that intravitreal dosing with AAV8-RS1 leads to systemic immune activation with an increase of activated lymphocytes, macrophages, and proinflammatory cytokines.

Effectiveness and Safety of Pixantrone for the Treatment of Relapsed or Refractory Diffuse Large B-Cell Lymphoma in Every-Day Clinical Practice: The Italian Cohort of the PIXA Registry.

INTRODUCTION: Treatment of relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) represents a challenge for clinicians due to the lack of therapeutic options. DLBCL is not a rare disease in Italy. Pixantrone is an aza-anthracenedione, which, when compared to anthracyclines and anthracenediones, has a significantly reduced cardiotoxicity while maintaining good anti-tumor activity. However, the evidence on the use of pixantrone in the context of daily clinical practice is scarce. METHODS: We focused on the Italian patient subset of a larger European retrospective study (the PIXA Registry) to assess the efficacy and safety of pixantrone in a real-life DLBCL population. The molecular profile of the disease and its impact on drug efficacy were also assessed. RESULTS: Fifteen heavily pretreated DLBCL patients (13 males and 2 females) underwent treatment with pixantrone for a median of 2 cycles (range 1-6). Eight patients were bcl2 positive, 7 bcl6 positive, and 4 myc positive; 4 patients were diagnosed as double-hit, and 2 as triple-hit DLBCL. The overall response rate was 26.7% with a best response rate of 46.7%. Three patients had grade IV adverse events, which caused drug discontinuation. Four patients had 5 cases of grade III toxicities (1 thrombocytopenia, 1 stomatitis, and 3 neutropenia). One mild cardiac toxicity (sinus tachycardia for which no action was required) was possibly related to the study drug. CONCLUSION: Our data documented drug efficacy that is satisfactory for this high-risk subset of patients with an acceptable toxicity profile. Results indicate that pixantrone could be a significant treatment option in patients with R/R aggressive DLBCL treated in everyday clinical practice.

Helicobacter cinaedi-Associated Refractory Cellulitis in Patients with X-Linked Agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is characterized by severe or recurrent infections, hypogammaglobulinemia, and circulating B cell deficiency. The frequent pathogens seen in patients with XLA include Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, and enterovirus as well as Campylobacter and Helicobacter species. Here, we describe two patients with XLA who developed cellulitis and bacteremia caused by Helicobacter cinaedi even when administered an appropriate immunoglobulin replacement therapy. H. cinaedi may be difficult to isolate using a conventional blood culture system and could be identified by sequence analysis and mass spectrometry. H. cinaedi infection causes recurrent symptoms frequently, and patients require a long course of antibiotic treatment. Recently, the case of non-H. pylori Helicobacter (NHPH) infection such as H. cinaedi and H. bilis infection is increasing in number in patients with XLA. Systemic NHPH infection should be suspected, and extensive microbiological analysis should be performed to appropriately treat patients with XLA who present with fever and skin lesions.

Pharmacological Inhibition of MALT1 Protease Leads to a Progressive IPEX-Like Pathology.

Genetic disruption or short-term pharmacological inhibition of MALT1 protease is effective in several preclinical models of autoimmunity and B cell malignancies. Despite these protective effects, the severe reduction in regulatory T cells (Tregs) and the associated IPEX-like pathology occurring upon congenital disruption of the MALT1 protease in mice has raised concerns about the long-term safety of MALT1 inhibition. Here we describe the results of a series of toxicology studies in rat and dog species using MLT-943, a novel potent and selective MALT1 protease inhibitor. While MLT-943 effectively prevented T cell-dependent B cell immune responses and reduced joint inflammation in the collagen-induced arthritis rat pharmacology model, in both preclinical species, pharmacological inhibition of MALT1 was associated with a rapid and dose-dependent reduction in Tregs and resulted in the progressive appearance of immune abnormalities and clinical signs of an IPEX-like pathology. At the 13-week time point, rats displayed severe intestinal inflammation associated with mast cell activation, high serum IgE levels, systemic T cell activation and mononuclear cell infiltration in multiple tissues. Importantly, using thymectomized rats we demonstrated that MALT1 protease inhibition affects peripheral Treg frequency independently of effects on thymic Treg output and development. Our data confirm the therapeutic potential of MALT1 protease inhibitors but highlight the safety risks and challenges to consider before potential application of such inhibitors into the clinic.

Megalocórnea esencial: relato de caso / Primary megalocornea: Case report

El neonato tiene un diámetro horizontal de la córnea, generalmente de hasta 10 mm, con un crecimiento de hasta 2 mm en los primeros 2 años de vida. Presentamos un caso de megalocórnea, un trastorno raro, recesivo, ligado al cromosoma X, en un niño de 3 meses de edad, buscando revisar lo que la literatura médica aporta como información sobre la enfermedad, así como los parámetros diagnósticos y de seguimiento de sus principales diagnósticos diferenciales

The neonate has a horizontal diameter of the cornea, usually up to 10 mm with growth up to 2 mm in the first 2 years of life. We report a case of megalocornea, a rare, recessive, X-linked disorder in a 3-month-old child, seeking to review what the medical literature brings information about the condition, as well as diagnostic and follow-up parameters, of its main differential diagnoses

Primary megalocornea: Case report. / Megalocórnea esencial: relato de caso.

The neonate has a horizontal diameter of the cornea, usually up to 10mm with growth up to 2mm in the first 2 years of life. We report a case of megalocornea, a rare, recessive, X-linked disorder in a 3-month-old child, seeking to review what the medical literature brings information about the condition, as well as diagnostic and follow-up parameters, of its main differential diagnoses.

A novel nonsense variant in PLS3 causes X-linked osteoporosis in a Chinese family.

Osteoporosis is a complex bone metabolic disorder. Genetic factors play an important role in the development of osteoporosis. Mutations in more than 15 genes have been identified to be responsible for osteoporosis to date. Most recently, the gene PLS3 encoding plastin 3 was recognized to be involved in X-linked osteoporosis. Here, we recruited a four-generation Chinese family with X-linked osteoporosis, which had its onset in childhood and was characterized by peripheral fractures and low bone mineral density. All affected individuals shared a nonsense variant (c.244C > T) in exon 4 of PLS3 on Xq23. The variant in affected individuals segregated with the osteoporosis phenotype. By restriction analysis using Dra I, this variant was confirmed in all affected individuals but was not detected in unaffected family members or in 100 unrelated Chinese male controls. The variant was predicted to cause a premature termination of messenger RNA (mRNA) translation (p.Gln82*). The mutant mRNA degraded via the mechanism of "nonsense-mediated mRNA decay." In the present study, we identified a novel nonsense variant of PLS3 in early-onset X-linked osteoporosis and provided a novel insight into the molecular mechanism underlying the pathogenesis of osteoporosis.

Great clinical variability of Nance Horan syndrome due to deleterious NHS mutations in two unrelated Spanish families.

Background: Nance-Horan syndrome (NHS) is an X-linked rare congenital disorder caused by mutations in the NHS gene. Clinical manifestations include congenital cataracts, facial and dental dysmorphism and, in some cases, intellectual disability. The aim of the present work was to identify the genetic cause of this disease in two unrelated Spanish NHS families and to determine the relative involvement of this gene in the pathogenesis.Materials and methods: Four members of a two-generation family, three males and one female (Family 1), and seven members of a three-generation family, two males and five females (Family 2) were recruited and their index cases were screened for mutations in the NHS gene and 26 genes related with ocular congenital anomalies by NGS (Next Generation Sequencing).Results: Two pathogenic variants were found in the NHS gene: a nonsense mutation (p.Arg373X) and a frameshift mutation (p.His669ProfsX5). These mutations were found in the two unrelated NHS families with different clinical manifestations.Conclusions: In the present study, we identified two truncation mutations (one of them novel) in the NHS gene, associated with NHS. Given the wide clinical variability of this syndrome, NHS may be difficult to detect in individuals with subtle clinical manifestations or when congenital cataracts are the primary clinical manifestation which makes us suspect that it can be underdiagnosed. Combination of genetic studies and clinical examinations are essential for the clinical diagnosis optimization.

An Ashkenazi Jewish founder mutation in CACNA1F causes retinal phenotype in both hemizygous males and heterozygous female carriers.

Background: Mutations in CACNA1F have been mainly associated with X-linked incomplete congenital stationary night blindness (icCSNB). Variable phenotypic expression in females was reported in some families. We report here three non-related Ashkenazi Jewish families originating in Eastern Europe, that included males and a many affected females, initially diagnosed with variable retinal phenotypes.Materials and Methods: Whole exome sequencing (WES), Sanger sequencing and microsatellite haplotyping were used for genetic analysis. Complete ophthalmologic examination was performed including visual acuity, refraction, colour vision, slit-lamp, fundoscopy and electroretinography (ERG).Results: We identified four affected males, showing moderate visual impairment, and seven female carriers, six of them presenting mild to moderate visual impairment. Infantile nystagmus was found in all affected males and in 5/7 females. Nyctalopia and myopia were common in both males and females. Initial clinical differential diagnosis included cone-dystrophy, cone-rod dystrophy, cone-dystrophy with supernormal rod response or CSNB based on ERG results. WES and Sanger sequencing revealed a previously described missense mutation c.2225T>G; p.(F742C) in CACNA1F (NM_001256789.2) in all three families, encompassed by a shared haplotypeConclusions: Our data suggests that p.(F742C) in CACNA1F is an X-linked founder mutation in Ashkenazi Jews originating in Eastern Europe. This mutation causes a mild-to-moderate icCSNB phenotype, expressed in most female carriers. A targeted test for this variant in suspected patients may initiate diagnostic analysis. Our results highlight the relevance of WES in the clinic, allowing fast and accurate diagnosis for unclear and variable clinical phenotype and in pedigrees with multiple possible inheritance patterns.

Whole-exome sequencing identifies a donor splice-site variant in SMPX that causes rare X-linked congenital deafness.

BACKGROUND: X-linked deafness-4 (DFNX4) caused by functional loss of SMPX is a nonsyndromic form of progressive hearing loss with post-lingual onset. Herein, we describe a male neonate from an ethnic Han Chinese family who presented with congenital deafness. METHODS: The proband and the family members were subjected to comprehensively hearing screen. Genetic testing was carried out using whole-exome sequencing (WES). The result was verified by Sanger sequencing. Functional characterization of the identified variant was completed by reverse transcription PCR (RT-PCR), Sanger sequencing, and fluorogenic quantitative PCR (qPCR). RESULTS: The proband was diagnosed with progressive sensorineural hearing loss. The proband's mother showed normal hearing at present. The proband's maternal grandmother exhibited mild HL since the age of 50. Using whole-exome sequencing (WES), we identified a donor splice-site variant (NM_014332.2: c.132 + 1G>A) in the SMPX gene in the proband. The mother and maternal grandmother were both carriers, which suggested a X-linked inheritance of the condition in the family. RT-PCR and Sanger sequencing revealed that four alternative splice pairs within intron 3 have led to four aberrant RNAs transcripts, including two non-canonical splice-pairs (GC-AG and CT-AG). The variant generated a novel frameshift variant, creating a premature termination codon (PTC) upstream of a newly formed splice site (p.Met45Glyfs*16). SMPX mRNA expression assay showed that the PTC has caused degradation of mRNA via nonsense-mediated mRNA decay (NMD). CONCLUSION: This is the first study to report a SMPX (DFNX4) splicing variant in a Chinese family. These findings, especially congenital deafness, contributed to existing knowledge regarding the genotypic and phenotypic spectrum of SMPX-associated hearing loss.

Defective DNA Polymerase α-Primase Leads to X-Linked Intellectual Disability Associated with Severe Growth Retardation, Microcephaly, and Hypogonadism.

Replicating the human genome efficiently and accurately is a daunting challenge involving the duplication of upward of three billion base pairs. At the core of the complex machinery that achieves this task are three members of the B family of DNA polymerases: DNA polymerases α, δ, and ε. Collectively these multimeric polymerases ensure DNA replication proceeds at optimal rates approaching 2 × 103 nucleotides/min with an error rate of less than one per million nucleotides polymerized. The majority of DNA replication of undamaged DNA is conducted by DNA polymerases δ and ε. The DNA polymerase α-primase complex performs limited synthesis to initiate the replication process, along with Okazaki-fragment synthesis on the discontinuous lagging strand. An increasing number of human disorders caused by defects in different components of the DNA-replication apparatus have been described to date. These are clinically diverse and involve a wide range of features, including variable combinations of growth delay, immunodeficiency, endocrine insufficiencies, lipodystrophy, and cancer predisposition. Here, by using various complementary approaches, including classical linkage analysis, targeted next-generation sequencing, and whole-exome sequencing, we describe distinct missense and splice-impacting mutations in POLA1 in five unrelated families presenting with an X-linked syndrome involving intellectual disability, proportionate short stature, microcephaly, and hypogonadism. POLA1 encodes the p180 catalytic subunit of DNA polymerase α-primase. A range of replicative impairments could be demonstrated in lymphoblastoid cell lines derived from affected individuals. Our findings describe the presentation of pathogenic mutations in a catalytic component of a B family DNA polymerase member, DNA polymerase α.

Unusual manifestations of visceral leishmaniasis in children: a case series and its spatial dispersion in the western region of São Paulo state, Brazil.

BACKGROUND: Visceral leishmaniasis (VL) is becoming endemic in São Paulo state, in the southeastern region of Brazil. Unusual manifestations with non-specific signs and symptoms may make diagnosis difficult and delay treatment, increasing the risk of severity and death, particularly in new endemic areas. There are few studies on patients with these characteristics in Brazil. We describe a case series of unusual manifestations of VL in children and its spatial dispersion in the western region of São Paulo state. CASES PRESENTATION: From 2009 to 2014, five clinical cases involving children treated in the Regional Hospital of Presidente Prudente (RH) were selected. Two patients had multiple relapses requiring liposomal amphotericin B; one patient had VL-cytomegalovirus-dengue co-infection and liver injury; one patient was diagnosed with X-linked agammaglobulinemia, a primary immunodeficiency; and one patient was diagnosed with VL-human immunodeficiency virus/acquired immunodeficiency syndrome (VL-HIV/AIDS) co-infection. Primary or secondary immunodeficiencies were found in four children, and associated viral infections were found in three children. Three patients were referred from other hospitals to RH. With regard to the geographic spread of VL, more cases were found in the northern area, in the epicenter of the infection where the first cases were registered, flowing south; a spatial-temporal occurrence was found. CONCLUSIONS: Primary and secondary immunodeficiencies and viral co-infectious should be considered among unusual manifestations of VL, especially in those with multiple relapses. Spatial-temporal occurrence was found. Thus, integrated actions and effective monitoring of the disease are needed to complement curative practices to stem the tide of the epidemic.

Focus on neonatal and infantile onset of nephrogenic syndrome of inappropriate antidiuresis: 12 years later.

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), first described in 2005, is a rare genetic X-linked disease, presenting with hyponatremia, hyposmolarity, euvolemia, inappropriately concentrated urine, increased natriuresis, and undetectable or very low arginine-vasopressine (AVP) circulating levels. It can occur in neonates, infants, or later in life. NSIAD must be early recognized and treated to prevent severe hyponatremia, which can show a dangerous impact on neonatal outcome. In fact, it potentially leads to death or, in case of survival, neurologic sequelae. This review is an update of NSIAD 12 years after the first description, focusing on reported cases of neonatal and infantile onset. The different molecular patterns affecting the AVP receptor 2 (V2R) and determining its gain of function are reported in detail; moreover, we also provide a comparison between the different triggers involved in the development of hyponatremia, the evolution of the symptoms, and modality and efficacy of the different treatments available.

Pathobiology of Christianson syndrome: Linking disrupted endosomal-lysosomal function with intellectual disability and sensory impairments.

Christianson syndrome (CS) is a recently described rare neurogenetic disorder presenting early in life with a broad range of neurological symptoms, including severe intellectual disability with nonverbal status, hyperactivity, epilepsy, and progressive ataxia due to cerebellar atrophy. CS is due to loss-of-function mutations in SLC9A6, encoding NHE6, a sodium-hydrogen exchanger involved in the regulation of early endosomal pH. Here we review what is currently known about the neuropathogenesis of CS, based on insights from experimental models, which to date have focused on mechanisms that affect the CNS, specifically the brain. In addition, parental reports of sensory disturbances in their children with CS, including an apparent insensitivity to pain, led us to explore sensory function and related neuropathology in Slc9a6 KO mice. We present new data showing sensory deficits in Slc9a6 KO mice, which had reduced behavioral responses to noxious thermal and mechanical stimuli (Hargreaves and Von Frey assays, respectively) compared to wild type (WT) littermates. Immunohistochemical and ultrastructural analysis of the spinal cord and peripheral nervous system revealed intracellular accumulation of the glycosphingolipid GM2 ganglioside in KO but not WT mice. This cellular storage phenotype was most abundant in neurons of lamina I-II of the dorsal horn, a major relay site in the processing of painful stimuli. Spinal cords of KO mice also exhibited changes in astroglial and microglial populations throughout the gray matter suggestive of a neuroinflammatory process. Our findings establish the Slc9a6 KO mouse as a relevant tool for studying the sensory deficits in CS, and highlight selective vulnerabilities in relevant cell populations that may contribute to this phenotype. How NHE6 loss of function leads to such a multifaceted neurological syndrome is still undefined, and it is likely that NHE6 is involved with many cellular processes critical to normal nervous system development and function. In addition, the sensory issues exhibited by Slc9a6 KO mice, in combination with our neuropathological findings, are consistent with NHE6 loss of function impacting the entire nervous system. Sensory dysfunction in intellectually disabled individuals is challenging to assess and may impair patient safety and quality of life. Further mechanistic studies of the neurological impairments underlying CS and other genetic intellectual disability disorders must also take into account mechanisms affecting broader nervous system function in order to understand the full range of associated disabilities.