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Mutations in SH2D1A, encoding the intracellular adaptor signaling lymphocyte activation molecule associated protein (SAP), are associated with X-linked lymphoproliferative disease type 1 (XLP1). We identified a novel hemizygous SH2D1A c.49G > A (p.E17K) variant in a 21-year-old patient with fatal Epstein-Barr virus infection-associated hemophagocytic lymphohistiocytosis. Cellular and biochemical assays revealed normal expression of the SAP variant protein, yet binding to phosphorylated CD244 receptor was reduced by >95%. Three healthy brothers carried the SH2D1A c.49G > A variant. Thus, data suggest that this variant represents a pathogenic mutation, but with variable expressivity. Importantly, our results highlight challenges in the clinical interpretation of SH2D1A variants and caution in using functional flow cytometry assays for the diagnosis of XLP1., (© 2020 The Authors. Pediatric Blood & Cancer published by Wiley Periodicals, Inc.)

Background: Perforin, encoded by PRF1, is a pore-forming protein crucial for lymphocyte cytotoxicity. Biallelic PRF1 nonsense mutations invariably result in early-onset hemophagocytic lymphohistiocytosis (HLH), termed familial HLH type 2 (FHL2). In contrast, biallelic PRF1 missense mutations may give rise to later-onset disease and more variable manifestations., Procedure: We retrospectively searched our database for patients from families with siblings carrying biallelic PRF1 missense mutations where at least one sibling did not develop HLH, and for patients with biallelic PRF1 missense mutations and an atypical presentation of disease. We reviewed their clinical, genetic, and immunological characteristics., Results: In all, we identified 10 such patients, including three sibling pairs with discordant manifestations. Interestingly, in two families, siblings of late-onset HLH patients developed Hodgkin lymphoma but no HLH. In a third family, one sibling presented with recurrent HLH episodes, whereas the other remains healthy. Of note, the affected sibling also suffered from systemic lupus erythematosus. Additional unrelated patients with biallelic PRF1 missense mutations were affected by neurological disease without classical signs of HLH, gastrointestinal inflammation as initial presentation of disease, as well as a hematological malignancy. Compared to early-onset FHL2 patients, the patients with an atypical presentation displayed a partial recovery of NK cell cytotoxicity upon IL-2 stimulation in vitro., Conclusions: Our findings substantiate and expand the spectrum of clinical presentations of perforin deficiency, linking PRF1 missense mutations to lymphoma susceptibility and highlighting clinical variability within families. PRF1 mutations should, therefore, be considered as a cause of several diseases disparate to HLH., (© 2015 Wiley Periodicals, Inc.)

Background: Primary hemophagocytic lymphohistiocytosis (HLH) represents a group of inherited hyperinflammatory immunodeficiencies, including familial HLH (FHL), Griscelli syndrome type 2 (GS2), and X-linked lymphoproliferative syndrome (XLP). We previously reported an annual incidence of suspected primary HLH in Sweden 1971-1986 of 0.12 per 100,000 children. Here, we determined if the incidence had increased with concomitant awareness., Procedure: Children <15 years old presenting with HLH 1987-2006 in Sweden were identified through the national mortality registry as well as by nation-wide inquiries to all pediatric centers. HLH was diagnosed according to the HLH-2004 diagnostic guidelines (in case of missing data of at least three of the eight diagnostic criteria, fulfillment of four was sufficient for inclusion). We defined primary HLH as patients presenting with HLH requiring transplantation or dying of disease., Results: Remarkably, the minimal annual incidence rate of primary HLH remained 0.12 per 100,000 children, equating to 1.8 per 100,000 live births. Notably, an increased overall survival was observed in 1997-2006, relative to the period 1987-1996. During the subsequent 5-year period, 2007-2011, the incidence of genetically and/or functionally verified primary HLH was 0.15 per 100,000 children per year, suggesting that new assays may aid the identification of patients with primary HLH., Conclusion: The annual incidence of primary HLH in Sweden is 0.12-0.15 per 100,000 children per year. Pediatr Blood Cancer 2015;62:346-352. © 2014 Wiley Periodicals, Inc., (© 2014 Wiley Periodicals, Inc.)

Background: Patients with Langerhans cell histiocytosis (LCH) may develop neurodegeneration and other central nervous system (CNS) dysfunctions revealed by brain magnetic resonance imaging (MRI). We estimated the incidence and pattern of pathological brain MRI findings in a well-defined, population-based cohort of children with LCH., Methods: Among children under 15 years of age diagnosed with LCH in the Stockholm County during 1992-2001, brain MRI was performed at a single center in children with clinical and/or laboratory signs of CNS involvement, including endocrine dysfunction., Results: Out of the 29 children (16 males, 13 females) diagnosed with LCH, brain MRI was performed based on clinical indications in 16 children (55%) with either abnormal endocrine findings (n = 6), such as diabetes insipidus (n = 5), low IGF-1 (n = 1), or panhypopituitarism (n = 1), or clinical CNS symptoms (n = 10). CNS MRI abnormalities were demonstrated in eight children (28%), at a median time of 3.5 years after LCH diagnosis (range 1-11.4 years). Altogether 7 of the 29 children (24%) had MRI findings associated with neurodegeneration, corresponding to a minimal incidence of 2.1/10(6) children per year. Neurodegenerative abnormalities tended to be more frequent in patients with craniofacial involvement (P = 0.12)., Conclusions: The minimal annual incidence rate of neurodegenerative associated radiographic findings in LCH is estimated at 2.1/10(6) children (24% of all children with LCH). An important question is whether all patients with LCH, or certain forms of LCH, should be recommended for a late follow-up examination including MRI. In patients with CNS-LCH, neurological, neuropsychological, neurophysiological, neurochemical and neuroradiological follow-up assessment is suggested., (Copyright © 2010 Wiley-Liss, Inc.)

Background: We studied the relation between unrelieved symptoms in terminally ill children and the psychological well-being in the bereaved parents 4-9 years after their loss., Procedure: We contacted parents in Sweden who had lost a child to a malignancy 1992-1997. The parents were asked to assess symptoms affecting their child's well-being during his or her last month of life, and their own current psychological well-being., Results: Altogether 449/561 (80%) eligible parents supplied information on 19 specific symptoms that may occur in children with a malignancy and how each of these symptoms had affected their child's well-being during his or her last month of life (not applicable, none, low, moderate, or severe). These results were linked to questions concerning the parents' self-assessed mental health. Parents of children who were affected by disturbed sleep also had increased risk to develop these symptoms; RR 2.0 [1.4-2.9] for depression, 1.8 [1.3-2.5] for anxiety, 1.5 [1.2-1.8] for decreased psychological well-being, and 1.5 [1.3-1.9] for decreased quality of life., Conclusions: Bereaved parents whose children were affected by anxiety or disturbed sleep due to anxiety or pain had an increased risk of long-term psychological morbidity. Reducing psychological complications in seriously ill children may also improve the psychological well-being in bereaved parents.

Background: Griscelli syndrome type 2 (GS2) is an autosomal-recessive immunodeficiency caused by mutations in RAB27A, clinically characterized by partial albinism and haemophagocytic lymphohistocytosis (HLH). We evaluated the frequency of RAB27A mutations in 21 unrelated patients with haemophagocytic syndromes without mutations in familial HLH (FHL) causing genes or an established diagnosis of GS2. In addition, we report three patients with known GS2. Moreover, neurological involvement and RAB27A mutations in previously published patients with genetically verified GS2 are reviewed., Procedure: Mutation analysis of RAB27A was performed by direct DNA sequencing. NK cell activity was evaluated and microscopy of the hair was performed to confirm the diagnosis., Results: RAB27A mutations were found in 1 of the 21 families. This Swedish family had three affected children with heterozygous compound mutations consisting of a novel splice error mutation, [c.239G>C], and a nonsense mutation, [c.550C>T], p.R184X. The three additional children all carried homozygous RAB27A mutations, one of which is a novel splice error mutation, [c.240-2A>C]. Of note, five of the six patients displayed neurological symptoms, while three out of six patients displayed NK cell activity within normal reference values, albeit low. A literature review revealed that 67% of GS2 patients have been reported with neurological manifestations., Conclusions: Identification of RAB27A mutations can facilitate prompt diagnosis and treatment, and aid genetic counselling and prenatal diagnosis. Since five of six patients studied herein initially were diagnosed as having FHL, we conclude that the diagnosis of GS2 may be overlooked, particularly in fair-haired patients with haemophagocytic syndromes.

Background: We investigated the characteristics, frequency, and prognosis of central nervous system (CNS) involvement in patients with hemophagocytic lymphohistiocytosis (HLH)., Procedure: Neurological manifestations were prospectively assessed in 92 children with HLH treated from January 2004 to August 2008 at our center; 82 (89%) had associated viral infections (69 Epstein-Barr virus), one empyema, while no associated disease was identified in the remaining nine. Prior to treatment, all underwent cerebrospinal fluid (CSF) evaluation, brain computer tomography (CT) and/or magnetic resonance imaging (MRI)., Results: At diagnosis, 43 (47%) children had CNS involvement. Twelve patients (13%) had neurological symptoms, including seizures, ataxia, coma, cranial nerve palsy, and hemiplegia. All patients improved after 8 weeks of therapy, but one later developed progressive neurological symptoms and six discontinued therapy due to progressive systemic symptoms and/or other reasons. Fifteen patients had CSF abnormalities that all normalized completely after 6 weeks of treatment. Thirty-six patients (39%) had neuroradiological abnormalities; with 5 still under treatment, 15 lost to follow-up, and 16 followed after completion of therapy. Of these 16, 12 improved, 3 were unchanged, and 1 progressed. Among all 21 children with CNS involvement followed after completion of therapy, 10 recovered completely, 10 improved (3 had remaining neuroradiological abnormalities), and 1 progressed clinically and neuroradiologically., Conclusion: Most patients reported here suffered from secondary HLH and since CNS involvement is frequent in HLH, brain MRI at diagnosis is recommended in all HLH patients. Clinical and CSF abnormalities often improved within 8 weeks of therapy, but CT/MRI abnormalities normalized more slowly and less frequently., (Copyright 2009 Wiley-Liss, Inc.)

Background: Progressive neurodegeneration may result in potentially severe cognitive and motor dysfunctions as a complication of Langerhans cell histiocytosis (LCH), a suggested IL-17A-associated inflammatory condition. To detect this complication (CNS-LCH) early and to evaluate the potential efficacy of therapeutic interventions, biomarkers detecting and measuring ongoing neurodegeneration would be valuable. We evaluated cerebrospinal fluid (CSF) biomarkers of ongoing neurodegeneration in CNS-LCH patients., Procedure: Nine patients with endocrine, neuromotor, cognitive or/and behavioral abnormalities as well as neuroradiological evidence of CNS-LCH were evaluated 4-12 years after LCH diagnosis for CSF levels of neurofilament protein light chain (NF-L), glial fibrillary acid protein (GFAp), and total tau protein (TAU). Two patients were analyzed longitudinally. One hundred ten children with newly diagnosed acute lymphoblastic leukemia (ALL) served as controls., Results: NF-L, TAU, and GFAp levels were elevated in four, six, and eight of nine patients studied, respectively. NF-L (P < 0.001) and GFAp (P < 0.001) were higher in patients than in controls (TAU not analyzed in controls). The patient with most severe clinical and neuroradiological CNS-LCH displayed the highest levels of NF-L and GFAp whereas three patients without signs of systemic disease had low TAU levels and normal/slightly elevated NF-L. NF-L tended to be higher at radiological progression of neurodegeneration than at status quo (P = 0.07). Notably, we experienced frequent lumbar puncture complications in these patients., Conclusions: CSF levels of NF-L, TAU, and GFAp appear to be elevated in CNS-LCH. It would be valuable if these markers were validated in order to serve as markers for early CNS-LCH, to monitor disease progression and to evaluate various treatment attempts for CNS-LCH.

A patient with previously unrecognized X-linked chronic granulomatous disease (X-CGD) died of multi-organ failure, secondary to ongoing infection and hemophagocytic lymphohistiocytosis (HLH). Post mortem histological investigations were compatible with X-CGD, and a CYBB gene mutation was confirmed. No homozygous mutations in the genes encoding perforin (PRF1), MUNC 13-4 or syntaxin-11 (STX11) were found; however, there was a heterozygous alteration c.1471G>A in the PRF1 gene causing a p.Asp491Asn substitution. Although this substitution has not been reported to cause primary or secondary HLH, we speculate that it may have made the patient more susceptible for HLH under the circumstances of ongoing infection associated with X-CGD., (Copyright 2008 Wiley-Liss, Inc.)

Background: Griscelli syndrome type 2 (GS2), the X-linked lymphoproliferative (XLP) and the Chédiak-Higashi (CHS) syndromes are diseases that all may develop hemophagocytic syndromes. We wanted to investigate whether the treatment protocols for hemophagocytic lymphohistiocytosis (HLH) can also be used for these syndromes., Procedure: In the HLH-94/HLH-2004 treatment study registries, we evaluated all patients with GS2 (n = 5), XLP (n = 2) or CHS (n = 2) treated between 1994 and 2004., Results: All patients responded to the therapy, and all are alive but one (suffering from CHS), with a mean follow-up of 5.6 years. All GS2, one XLP and one CHS patient underwent hematopoietic stem cell transplant. Mean follow-up post transplant was 6.0 years. Six of the seven transplanted children achieved non-active disease status at the time for SCT. Neurological sequelae were reported in all, except for the XLP patients., Conclusions: Our results indicate that HLH treatment can be an effective first line treatment to induce remission in patients with GS2, XLP and CHS that have developed a hemophagocytic syndrome. We suggest that these patients should be included as a separate cohort in the international HLH study., ((c) 2008 Wiley-Liss, Inc.)

Background: Patients with Langerhans cell histiocytosis (LCH) may develop neurodegeneration and significant CNS sequelae, affecting a significant proportion of the patients. We here aimed to investigate the neuropsychological consequences in more detail., Methods: Using an extensive neuropsychological test battery, we evaluated nine LCH patients, 6-20 years old, with radiological signs indicative of neurodegeneration., Results: Altogether 3/9 patients performed below 1 SD of normal for age on full IQ. Detailed analysis revealed that 4/9 had deficient performance IQ, whereas 1/9 had subnormal verbal IQ (defined as below 1 SD). Furthermore, 3/8 patients showed slow speed of performance for age. Notably, 8/9 (89%) had deficient verbal working memory and 7/8 (88%) performed below normal on visual-spatial working memory., Conclusions: The results indicate a specific, uneven neuropsychological profile in patients affected by CNS-LCH, with a decline particularly on perceptual tasks whereas the verbal performance was not as negatively influenced. Furthermore, verbal and visual-spatial working memory functions were below normal for age in all but one patient studied. LCH may easily be misdiagnosed, but it is important that individuals affected by CNS-LCH are diagnosed to provide advice and support. It remains a challenge to find a treatment reducing this unfortunate neurodegeneration., ((c) 2008 Wiley-Liss, Inc.)

Background: Langerhans cell histiocytosis is a rare disease of unknown etiology. We wanted to assess the population-based incidence of LCH in a well-defined cohort of children., Methods: We identified all children <15-years old treated with LCH during the 10 years period 1992-2001 at the Department of Pediatrics, Karolinska University Hospital in Stockholm, the referral center for children with LCH in Stockholm County. We also contacted the Departments of Dermatology, Orthopedics, and Neurosurgery for possible additional patients., Results: Twenty-nine children (16 males) with LCH were identified, with a median age at diagnosis of 3.8 years (2 months-13.7 years). All children but one had a definitive diagnosis of LCH. The minimum incidence of LCH is estimated to 8.9/10(6) children per year. At diagnosis, 20 children (69%) had single system (SS) and 9 (31%) multisystem (MS) manifestations. Five of the 20 children with SS eventually developed MS disease, thus 14 (48%) had MS involvement at the maximal extent of disease (4.3/10(6) children per year). Interestingly, 22 children (76%) were diagnosed during the fall (September-November, n = 12) and winter (December-February, n = 10) seasons, as compared to seven children during the spring (March-May = 1) and summer (June-August = 6) seasons (P = 0.005, Chi-square)., Conclusions: The incidence of childhood LCH in our study is higher than previously reported. In our patient cohort, LCH was more commonly diagnosed during the fall and winter season as compared to the spring and summer season. Whether this seasonal variation can be confirmed in larger studies and whether it has relevance for LCH pathophysiology remains to be elucidated., ((c) 2008 Wiley-Liss, Inc.)

In the present study, DNA sequencing of the genes SRGN, ARF6, AP3B1, and SH2D1A was performed in a well defined cohort of 18 families with familial hemophagocytic lymphohistiocytosis (FHL). A heterozygous nucleotide change (C > T) in the 3'untranslated region of the SRGN gene and a monoallelic 3-base pair deletion (c.2409&#95;2411delGAA) in exon 21 of the AP3B1 gene were observed in two different families. Additionally, two novel polymorphisms, one in intron 17 of AP3B1 and another in intron 2 of SH2D1A were identified. We conclude that mutations in SRGN, ARF6, and AP3B1 are not likely to be common in patients fulfilling the FHL criteria., ((c) 2008 Wiley-Liss, Inc.)

In a long-term single-center follow-up (median 16-years), we studied high-resolution computed tomography (HRCT) and pulmonary function testing (PFT) in pulmonary LCH. Diffusing capacity corrected for alveolar volume (K(CO)) and total lung capacity (TLC) were significantly decreased (P=0.016 and P=0.030, respectively) in patients with extensive HRCT abnormalities. Patients with late stage disease on HRCT had increased forced expiratory volume (FEV1.0)(P=0.037) and vital capacity (VC)(P=0.036). Disease monitoring is important in pulmonary LCH, and since PFT with diffusing capacity provides a measurement of the current lung function, it may be a valuable tool in monitoring pulmonary LCH, and a good complement to imaging., (Copyright (c) 2005 Wiley-Liss, Inc.)

In HLH-94, the first prospective international treatment study for hemophagocytic lymphohistiocytosis (HLH), diagnosis was based on five criteria (fever, splenomegaly, bicytopenia, hypertriglyceridemia and/or hypofibrinogenemia, and hemophagocytosis). In HLH-2004 three additional criteria are introduced; low/absent NK-cell-activity, hyperferritinemia, and high-soluble interleukin-2-receptor levels. Altogether five of these eight criteria must be fulfilled, unless family history or molecular diagnosis is consistent with HLH. HLH-2004 chemo-immunotherapy includes etoposide, dexamethasone, cyclosporine A upfront and, in selected patients, intrathecal therapy with methotrexate and corticosteroids. Subsequent hematopoietic stem cell transplantation (HSCT) is recommended for patients with familial disease or molecular diagnosis, and patients with severe and persistent, or reactivated, disease. In order to hopefully further improve diagnosis, therapy and biological understanding, participation in HLH studies is encouraged.