Case report: IKZF1-related early-onset CID is expected to be missed in TREC-based SCID screening but can be identified by determination of KREC levels.

This report illustrates a case that would have been missed in the most common screening algorithms used worldwide in newborn screening (NBS) for severe combined immunodeficiency (SCID). Our patient presented with a clinical picture that suggested a severe inborn error of immunity (IEI). The 6-month-old baby had normal T-cell receptor excision circle (TREC) levels but no measurable level of kappa-deleting recombination excision circles (KRECs) in the NBS sample. A de novo IKZF1-mutation (c.476A>G, p.Asn159Ser) was found. The clinical picture, immunologic workup, and genetic result were consistent with IKZF1-related combined immunodeficiency (CID). Our patient had symptomatic treatment and underwent allogeneic hematopoietic cell transplantation (HCT). IKZF1-related CID is a rare, serious, and early-onset disease; this case provides further insights into the phenotype, including KREC status.

A novel disorder involving dyshematopoiesis, inflammation, and HLH due to aberrant CDC42 function.

Hemophagocytic lymphohistiocytosis (HLH) is characterized by immune dysregulation due to inadequate restraint of overactivated immune cells and is associated with a variable clinical spectrum having overlap with more common pathophysiologies. HLH is difficult to diagnose and can be part of inflammatory syndromes. Here, we identify a novel hematological/autoinflammatory condition (NOCARH syndrome) in four unrelated patients with superimposable features, including neonatal-onset cytopenia with dyshematopoiesis, autoinflammation, rash, and HLH. Patients shared the same de novo CDC42 mutation (Chr1:22417990C>T, p.R186C) and altered hematopoietic compartment, immune dysregulation, and inflammation. CDC42 mutations had been associated with syndromic neurodevelopmental disorders. In vitro and in vivo assays documented unique effects of p.R186C on CDC42 localization and function, correlating with the distinctiveness of the trait. Emapalumab was critical to the survival of one patient, who underwent successful bone marrow transplantation. Early recognition of the disorder and establishment of treatment followed by bone marrow transplant are important to survival.

Strong expression of p53 protein in bone marrow samples after hematopoietic stem cell transplantation indicates risk of relapse in pediatric acute lymphoblastic leukemia patients.

BACKGROUND: For pediatric ALL patients that relapse or respond poorly to conventional chemotherapy treatment, HSCT is one treatment option. Still, relapse occurs in 30% of the children after HSCT. Mutations in the tumor suppressor gene TP53 which can lead to an altered p53 protein expression are rare at time of diagnosis of ALL, yet occur more frequent at relapse indicating a more aggressive disease. Our aim was to evaluate if alterations in the expression of the tumor suppressor protein p53 signaled a relapse in pediatric ALL patients post-HSCT and could guide for preemptive immunotherapy. PROCEDURE: Paraffin-embedded bone marrow samples from 46 children diagnosed with ALL between 1997 and 2010, and transplanted at Karolinska University Hospital, were analyzed for p53 by IHC. Samples were analyzed independently at diagnosis, before HSCT, and after HSCT 0-3 months, 3-6 months, and 6-12 months. RESULT: Strong expression of p53 in the bone marrow at 0-3-months after HSCT was associated with increased risk of relapse, odds ratio 2.63 (confidence interval 1.08-6.40) P = 0.033. CONCLUSION: Evaluation of p53 protein expression in bone marrow from pediatric ALL patients that undergo HSCT may be a potential, additional prognostic marker for predicting relapse after HSCT.

Severe combined immunodeficiency (SCID) presenting in childhood, with agammaglobulinemia, associated with novel compound heterozygous mutations in DCLRE1C.

Severe combined immunodeficiency (SCID) can be caused by deleterious mutations in DCLRE1C, leading to deficient non-homologous end joining by compromising the function of the Artemis protein. This impairs the process of V(D)J recombination of the T- and B-cell receptors and typically results in radiosensitive T-, B-, NK+ SCID presenting during the first months of life. We present a case of a 3-year-old girl with two novel compound heterozygous variants in DCLRE1C (c.58G>C and c.374A>C) that were associated with marked reduced numbers of peripheral T- and B-cells and undetectable total serum IgG. Despite the severe laboratory phenotype, the patient had a normal development, albeit failure to thrive (-2.5 to -3 SD), during her first years of life including day-care attendance at preschool for 1.5 years. After being diagnosed with pneumonia the clinical picture of SCID was recognized and the girl successfully underwent hematopoietic stem-cell transplantation.

Origins of STIL-TAL1 fusion genes in children who later developed paediatric T-cell acute lymphoblastic leukaemia: An investigation of neonatal blood spots.

SCL/TAL1 interrupting locus (STIL)-T-cell acute leukaemia (TAL1) fusion genes are present in approximately 11-27% of children with paediatric T-cell acute lymphoblastic leukaemia (T-ALL), but the developmental timing of the rearrangement is still unknown. To investigate whether the fusion gene can be detected in neonatal blood spots (NBSs) from paediatric patients diagnosed with T-cell ALL, we analysed DNA from 38 paediatric patients with T-ALL by nested polymerase chain reaction and electrophoresis. The STIL-TAL1 fusion gene was not detected in NBSs from any of the 38 patients with T-ALL, suggesting that STIL-TAL1 fusion genes are most probably postnatal events in paediatric T-ALL.

Clinical presentation of Griscelli syndrome type 2 and spectrum of RAB27A mutations.

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.

Characterization of PRF1, STX11 and UNC13D genotype-phenotype correlations in familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive lethal condition characterized by fever, cytopenia, hepatosplenomegaly and hemophagocytosis. The hallmark of FHL is defect apoptosis triggering and lymphocyte cellular cytotoxicity. Thus far three disease-causing genes (PRF1, UNC13D, STX11) have been identified. We performed a genotype-phenotype study in a large, multi-ethnic cohort of 76 FHL patients originating from 65 unrelated families. Biallelic mutations in PRF1, UNC13D and STX11 were demonstrated in 13/74 (18%), 6/61 (10%) and 14/70 (20%) patients, respectively. In 27/60 (45%) patients analyzed for all three genes, no molecular diagnosis was established. STX11 mutations were most common in Turkish families (7/28, 25%), whereas in Middle East families, PRF1 mutations were most frequent (6/13, 46%). No biallelic mutation was identified in most families of Nordic origin (13/14, 93%). Patients carrying PRF1 mutations had higher risk of early onset (age <6 months) compared to patients carrying STX11 mutations [adjusted odds ratio 8.23 (95% confidence interval [CI] = 1.20-56.40), P = 0.032]. Moreover, patients without identified mutations had increased risk of pathological cerebrospinal fluid (CSF) at diagnosis compared to patients with STX11 mutations [adjusted odds ratio 26.37 (CI = 1.90-366.82), P = 0.015]. These results indicate that the disease-causing mutations in FHL have different phenotypes with regard to ethnic origin, age at onset, and pathological CSF at diagnosis.

Sequence analysis of the SRGN, AP3B1, ARF6, and SH2D1A genes in familial hemophagocytic lymphohistiocytosis.

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_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.

Kostmann syndrome or infantile genetic agranulocytosis, part two: Understanding the underlying genetic defects in severe congenital neutropenia.

UNLABELLED: Congenital neutropenia in man was first reported 50 years ago by the Swedish paediatrician Rolf Kostmann. He coined the term 'infantile genetic agranulocytosis' for this condition, which is now known as Kostmann syndrome. Recent studies have revealed mutations in ELA-2, encoding the neutrophil granule protease, neutrophil elastase, in autosomal dominant neutropenia, and mutations in HAX-1, encoding an anti-apoptotic protein, in autosomal recessive neutropenia. CONCLUSION: Future studies should aim to clarify the mechanisms underlying the evolution of secondary malignancies in these patients.

Low plasma levels of the protein pro-LL-37 as an early indication of severe disease in patients with chronic neutropenia.

Chronic neutropenia comprises several different diseases that vary in degree of severity and management. We analysed the levels of the neutrophil-derived protein pro-LL-37 in plasma of patients with chronic neutropenia to assess whether it could be used to differentiate different categories of chronic neutropenia. All patients with severe congenital neutropenia were pro-LL-37 deficient. This was in contrast to patients with autoimmune or idiopathic neutropenia, who exhibited normal pro-LL-37 levels while patients with cyclic neutropenia displayed an oscillation of pro-LL-37 in plasma. Plasma levels of pro-LL-37 may thus prove useful for differential diagnosis of chronic neutropenia.