Novel mutations in the UNC13D gene carried by a Chinese neonate with hemophagocytic lymphohistiocytosis

Neonatal hemophagocytic lymphohistiocytosis: A meta-analysis of 205 cases

BACKGROUND

Neonatal hemophagocytic lymphohistiocytosis (nHLH), defined as HLH that presents in the first month of life, is clinically devastating. There have been few large descriptive studies of nHLH.

OBJECTIVES

The objective of this study was to perform a meta-analysis of published cases of nHLH.

METHODS

A comprehensive literature database search was performed. Cases of HLH were eligible for inclusion if clinical analysis was performed at age ≤30 days. Up to 70 variables were extracted from each case.

RESULTS

A total of 544 studies were assessed for eligibility, and 205 cases of nHLH from 142 articles were included. The median age of symptom onset was day of life 3 (interquartile range [IQR]: 0-11, n = 141). Median age at diagnosis was day of life 15 (IQR: 6-27, n = 87). Causes of HLH included familial HLH (48%, n = 99/205), infection (26%, n = 53/205), unknown (17%, n = 35/205), macrophage activation syndrome/rheumatologic (2.9%, n = 4/205), primary immune deficiency (2.0%, n = 5/205), inborn errors of metabolism (2.4%, n = 5/205), and malignancy (2.0%, n = 4/205). Fever was absent in 19% (n = 28/147) of all neonates and 39% (n = 15/38) of preterm neonates. Bicytopenia was absent in 26% (n = 47/183) of patients. Central nervous system (CNS) manifestations were reported in 63% of cases (n = 64/102). Liver injury (68%, n = 91/134) and/or liver failure (24%, n = 32/134) were common. Flow cytometry was performed in 22% (n = 45/205) of cases. Many patients (63%, n = 121/193) died within the period of reporting. Discernable values for HLH diagnostic criteria were reported between 30% and 83% of the time.

CONCLUSIONS

Evaluation of nHLH requires rapid testing for a wide range of differential diagnoses. HLH diagnostic criteria such as fever and bicytopenia may not occur as frequently in the neonatal population as in older pediatric populations. Neurologic and hepatic manifestations frequently occur in the neonatal population. Current reports of nHLH suggest a high mortality rate. Future publications containing data on nHLH should improve reporting quality by reporting all clinically relevant data.

Familial hemophagocytic lymphohistiocytosis in a neonate: Case report and literature review

RATIONALE

Familial hemophagocytic lymphohistiocytosis (FHL) is a potentially fatal disease that rarely presents in the neonatal period. Timely diagnosis is a key challenge owing to the atypical clinical manifestations. Here, we describe a case of FHL type 3 with disease onset in the early neonatal period and review the relevant literature. Our findings may provide insights into the diagnosis and treatment of this rare disease.

PATIENT CONCERNS

A 6-day-old male neonate presented with fever, hepatosplenomegaly, cytopenia, hyperferritinemia, hypofibrinogenemia, hemophagocytosis, and hypertriglyceridemia.

DIAGNOSIS

Considering the clinical picture (prolonged fever, progressive hepatosplenomegaly, high triglycerides, low fibrinogen, and high ferritin), along with abnormal natural killer-cell activity, combining sequence analysis of genomic DNA results (compound heterozygous mutations of UNC13D), the patient was finally diagnosed with FHL type 3 (FHL3).

INTERVENTIONS

The patient was initially treated with HLH-1994 protocol and subsequently switched to an oral regimen of ruxolitinib due to incomplete remission of the disease.

OUTCOMES

The trend of change in weekly cytokine levels, neutrophil counts, hemoglobin, and platelet counts indicated that the complete remission was not achieved after the treatment of HLH-1994 protocol. The platelet counts fluctuated within the normal range after oral administration of ruxolitinib. But soon after, the patient did not respond to treatment and eventually died of respiratory failure.

LESSON

Timely diagnosis of FHL is challenging. This case report illustrates that thrombocytopenia can be the first clinical sign of FHL with neonatal onset. Genetic testing, detection of cytokines, and flow cytometry should be performed as soon as possible to confirm the diagnosis. Given the high morbidity and mortality of FHL, pediatricians should have a high suspicion index for this disease.

Clinical, immunological and genetic findings in patients with UNC13D deficiency (FHL3): A systematic review

BACKGROUND

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive immune disorder that is caused by mutations in 6 different genes related to the formation and function of secretory lysosomes within cytotoxic T lymphocytes and natural killer (NK) cells. Thus, defect in these genes is associated with the accumulation of antigens due to defective cytotoxic function. FHL type 3 (FHL3) accounts for nearly 30-40% of FHL, and its underlying reason is mutation in UNC13D gene which encodes Munc13-4 protein.

METHODS

For the first time, we aimed to systematically review clinical features, immunologic data, and genetic findings of patients with FHL3. We conducted electronic searches for English-language articles in PubMed, Web of Science, EMBASE, and Scopus databases to collect comprehensive records related to patients with UNC13D mutations.

RESULTS

A total of 279 abstracts were initially reviewed for inclusion. Among them, 57 articles corresponding to 322 individual FHL3 patients fulfilled our selection criteria. Finally, 73 and 249 patients were considered as severe and mild feature groups, respectively. Our results confirmed that fever, hepatosplenomegaly, and hemophagocytosis are common clinical features in the disease. Moreover, reduced fibrinogen and NK cell activity, as well as increased ferritin and triglycerides, are important markers for early diagnosis of the FHL3 disease. Investigation of genotype showed that the most prevalent type and zygosity of UNC13D are splice-site errors and compound heterozygous, respectively.

CONCLUSION

FHL3 patients have a wide range of clinical manifestations, which makes it difficult to diagnose. Therefore, it seems that the sequencing of the entire UNC13D gene (coding and non-coding regions) is the most appropriate way to accurate diagnosis of FHL3 patients.

Platelet Munc13-4 regulates hemostasis, thrombosis and airway inflammation

Platelet degranulation is crucial for hemostasis and may participate in inflammation. Exocytosis in platelets is mediated by SNARE proteins and should be controlled by Munc13 proteins. We found that platelets express Munc13-2 and -4. We assessed platelet granule exocytosis in Munc13-2 and -4 global and conditional knockout (KO) mice, and observed that deletion of Munc13-4 ablates dense granule release and indirectly impairs alpha granule exocytosis. We found no exocytic role for Munc13-2 in platelets, not even in the absence of Munc13-4. In vitro, Munc13-4-deficient platelets exhibited defective aggregation at low doses of collagen. In a flow chamber assay, we observed that Munc13-4 acted as a rate-limiting factor in the formation of thrombi. In vivo, we observed a dose-dependency between Munc13-4 expression in platelets and both venous bleeding time and time to arterial thrombosis. Finally, in a model of allergic airway inflammation, we found that platelet-specific Munc13-4 KO mice had a reduction in airway hyper-responsiveness and eosinophilic inflammation. Taken together, our results indicate that Munc13-4-dependent platelet dense granule release plays essential roles in hemostasis, thrombosis and allergic inflammation.

Prognostic factors of early death in children with hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis is a rapidly progressing and fatal disease. Early identification of early death for HLH patients based on the laboratory findings at the time of diagnosis could improve the overall survival. A retrospective study was performed on 95 Chinese pediatric patients with HLH. Patients' data including clinical features and laboratory findings at diagnosis were collected. In a multivariate Cox proportional hazard regression model analysis, albumin≤27.75g/L (hazard ratio (HR)=11.82, 95% confidence interval (CI) 2.58-54.23; P=0.001), LDH≥3707.5 U/L (HR=4.15, 95%CI 1.43-12.01; P=0.009), and IL-10≥456pg/ml (HR=12.39, 95%CI 1.59-96.79; P=0.016) at diagnosis were independent prognostic factors of early death. The risk of early death was 33-fold increase in patients with three risk factors (HR=33.33; 95%CI 8.40-125.00; P<0.001), and 12-fold increase in patients with two risk factors (HR=12.80; 95%CI 2.34-69.80; P=0.002) when compared to it in patients with zero to one risk factor. Our results reveal that HLH patients with the risk of early death can be identified by laboratory findings at diagnosis, which may help guide the treatment decision making for this disease.

Comparison of Th1/Th2 cytokine profiles between primary and secondary haemophagocytic lymphohistiocytosis

Background

Haemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder of immune regulation, and HLH patients with mutations in genes including PRF1, UNC13D, STX11, STXBP2, SH2D1A, XIAP, and ITK were reported to be primary HLH. Due to the different treatment options, the differentiation between primary and secondary HLH is critical. Our previous studies have showed that a Th1/Th2 cytokine profile is diagnostic for HLH, yet the cytokine profiles between primary and secondary HLH have not been compared. The aim of the study was to test whether the Th1/Th2 cytokine profile could be used as a tool to differentiate between primary and secondary HLH.

Methods

A total of 45 hospitalized Chinese children with HLH during the period of February 2010 through September 2012 were enrolled in the study. Fifty healthy children were enrolled as controls. Primary HLH related genes were sequenced using genomic DNA samples. The Th1/Th2 cytokine levels including interferon-γ (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-10, IL-6, IL-4 and IL-2 were quantitatively determined by cytometric bead assay techniques.

Results

Primary HLH group (n = 4) included one patient with biallelic heterozygous mutations in PRF1 gene, and three patients with hemizygous mutation in SH2D1A gene. Based on the available genetic data, the other 41 patients were classified into the secondary HLH group. When compared the cytokine levels between the two groups, IL-4 level in primary-HLH was significantly lower than that in secondary HLH (P = 0.025), while IFN-γ level in primary HLH had a tendency of statistically lower than that in secondary HLH (P = 0.051). Area under receiver operating characteristic (ROC) curves of IL-4 and IFN-γ, IL-10, TNF-α, IL-2, and IL-6 levels were 0.841, 0.799, 0.506, 0.494, 0.457, and 0.250, respectively. ROC curves showed that 1.7 pg/ml of IL-4 had sensitivity and specificity for differentiation between primary and secondary HLH as 70.7 and 100.0 %, while 433.9 pg/ml of IFN-γ had sensitivity and specificity as 51.2 and 100.0 %, respectively.

Conclusions

HLH patients with lower IL-4 and IFN-γ levels have higher possibility to be primary HLH. The cytokine profile may be used as an additional tool for the quick differential diagnosis between primary and secondary HLH.

Electronic supplementary material

The online version of this article (doi:10.1186/s13052-016-0262-7) contains supplementary material, which is available to authorized users.