Loss of DIAPH1 causes SCBMS, combined immunodeficiency, and mitochondrial dysfunction.

BACKGROUND: Homozygous loss of DIAPH1 results in seizures, cortical blindness, and microcephaly syndrome (SCBMS). We studied 5 Finnish and 2 Omani patients with loss of DIAPH1 presenting with SCBMS, mitochondrial dysfunction, and immunodeficiency. OBJECTIVE: We sought to further characterize phenotypes and disease mechanisms associated with loss of DIAPH1. METHODS: Exome sequencing, genotyping and haplotype analysis, B- and T-cell phenotyping, in vitro lymphocyte stimulation assays, analyses of mitochondrial function, immunofluorescence staining for cytoskeletal proteins and mitochondria, and CRISPR-Cas9 DIAPH1 knockout in heathy donor PBMCs were used. RESULTS: Genetic analyses found all Finnish patients homozygous for a rare DIAPH1 splice-variant (NM_005219:c.684+1G>A) enriched in the Finnish population, and Omani patients homozygous for a previously described pathogenic DIAPH1 frameshift-variant (NM_005219:c.2769delT;p.F923fs). In addition to microcephaly, epilepsy, and cortical blindness characteristic to SCBMS, the patients presented with infection susceptibility due to defective lymphocyte maturation and 3 patients developed B-cell lymphoma. Patients' immunophenotype was characterized by poor lymphocyte activation and proliferation, defective B-cell maturation, and lack of naive T cells. CRISPR-Cas9 knockout of DIAPH1 in PBMCs from healthy donors replicated the T-cell activation defect. Patient-derived peripheral blood T cells exhibited impaired adhesion and inefficient microtubule-organizing center repositioning to the immunologic synapse. The clinical symptoms and laboratory tests also suggested mitochondrial dysfunction. Experiments with immortalized, patient-derived fibroblasts indicated that DIAPH1 affects the amount of complex IV of the mitochondrial respiratory chain. CONCLUSIONS: Our data demonstrate that individuals with SCBMS can have combined immune deficiency and implicate defective cytoskeletal organization and mitochondrial dysfunction in SCBMS pathogenesis.

Comparison of the clinical phenotype and haematological course of siblings with Fanconi anaemia.

Fanconi anaemia (FA) is a genetic disorder due to mutations in any of the 22 FANC genes (FANCA-FANCW) and has high phenotypic variation. Siblings may have similar clinical outcome because they share the same variants; however, such association has not been reported. We present the detailed phenotype and clinical course of 25 sibling sets with FA from two institutions. Haematological progression significantly correlated between siblings, which was confirmed in an additional 55 sibling pairs from the International Fanconi Anemia Registry. Constitutional abnormalities were not concordant, except for a moderate degree of concordance in kidney abnormalities and microcephaly.

Correlation between Apoptosis and in Situ Immune Response in Fatal Cases of Microcephaly Caused by Zika Virus.

Zika virus (ZIKV) is a single-stranded positive-sense RNA flavivirus that possesses a genome approximately 10.7 Kb in length. Although pro-inflammatory and anti-inflammatory cytokines and apoptotic markers belonging to the extrinsic and intrinsic pathways are suggested to be involved in fatal cases of ZIKV-induced microcephaly, their exact roles and associations are unclear. To address this, brain tissue samples were collected from 10 individuals, five of whom were diagnosed as ZIKV positive with microcephaly and a further five were flavivirus-negative controls that died because of other causes. Examination of material from the fatal cases of microcephaly revealed lesions in the cerebral cortex, edema, vascular proliferation, neuronal necrosis, gliosis, neuronophagy, calcifications, apoptosis, and neuron loss. The expression of various apoptosis markers in the neural parenchyma, including FasL, FAS, BAX, BCL2, and caspase 3 differed between ZIKV-positive cases and controls. Further investigation of type 1 and 2 helper T-cell cytokines confirmed a greater anti-inflammatory response in fatal ZIKV-associated microcephaly cases. Finally, an analysis of the linear correlation between tumor necrosis factor-α, IL-1ß, IL-4, IL-10, transforming growth factor-ß, and IL-33 expression and various apoptotic markers suggested that the immune response may be associated with the apoptotic phenomenon observed in ZIKV-induced microcephaly.

Preventive and therapeutic challenges in combating Zika virus infection: are we getting any closer?

The neuroteratogenic nature of Zika Virus (ZIKV) infection has converted what would have been a tropical disease into a global threat. Zika is transmitted vertically via infected placental cells especially in the first and second trimesters. In the developing central nervous system (CNS), ZIKV can infect and induce apoptosis of neural progenitor cells subsequently causing microcephaly as well as other neuronal complications in infants. Its ability to infect multiple cell types (placental, dermal, and neural) and increased environmental stability as compared to other flaviviruses (FVs) has broadened the transmission routes for ZIKV infection from vector-mediated to transmitted via body fluids. To further complicate the matters, it is genetically similar (about 40%) with the four serotypes of dengue virus (DENV), so much so that it can almost be called a fifth DENV serotype. This homology poses the risk of causing cross-reactive immune responses and subsequent antibody-dependent enhancement (ADE) of infection in case of secondary infections or for immunized individuals. All of these factors complicate the development of a single preventive vaccine candidate or a pharmacological intervention that will completely eliminate or cure ZIKV infection. We discuss all of these factors in detail in this review and conclude that a combinatorial approach including immunization and treatment might prove to be the winning strategy.

Immune activation in amniotic fluid from Zika virus-associated microcephaly.

Recent advances in the understanding of neuropathogenesis associated with Zika virus (ZIKV) infection has led to descriptions of neonatal microcephaly cases. However, none of these reports have evaluated the humoral response during ZIKV infection. We report here polyfunctional immune activation associated with increased interferon-gamma-inducible protein 10, interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF), monocyte chemoattractive protein 1 (MCP-1), and granulocyte colony-stimulating factor (G-CSF) levels in the amniotic fluid of ZIKV-positive pregnant women with neonatal microcephaly. These cytokines have been associated not only with neuronal damage, but also with differentiation and proliferation of neural progenitor cells. Our results suggested that the immune activation caused by ZIKV infection in the uterine environment could also interfere with fetal development. ANN NEUROL 2017;81:152-156.

Type III Interferons Produced by Human Placental Trophoblasts Confer Protection against Zika Virus Infection.

During mammalian pregnancy, the placenta acts as a barrier between the maternal and fetal compartments. The recently observed association between Zika virus (ZIKV) infection during human pregnancy and fetal microcephaly and other anomalies suggests that ZIKV may bypass the placenta to reach the fetus. This led us to investigate ZIKV infection of primary human trophoblasts (PHTs), which are the barrier cells of the placenta. We discovered that PHT cells from full-term placentas are refractory to ZIKV infection. In addition, medium from uninfected PHT cells protects non-placental cells from ZIKV infection. PHT cells constitutively release the type III interferon (IFN) IFNλ1, which functions in both a paracrine and autocrine manner to protect trophoblast and non-trophoblast cells from ZIKV infection. Our data suggest that for ZIKV to access the fetal compartment, it must evade restriction by trophoblast-derived IFNλ1 and other trophoblast-specific antiviral factors and/or use alternative strategies to cross the placental barrier.

Molecular and immunological characterization of DNA ligase IV deficiency.

DNA ligase IV (LIG4) deficiency is an extremely rare autosomal recessive primary immunodeficiency disease caused by the LIG4 mutation. To date, fewer than 30 cases of patients have been reported worldwide. No reversion mutations have been previously identified in LIG4. This study enrolled seven Chinese patients with LIG4 deficiency who presented with combined immunodeficiency, microcephaly, and growth retardation. One patient (P1) acquired non-Hodgkin lymphoma. Four patients had impaired T cell proliferation function and skewed T cell receptor diversity. Five novel mutations in LIG4 and a potential hotspot mutation (c.833G>T; p.R278L) in the Chinese population were identified. TA cloning analysis of T cells, NK cells, granulocytes, and oral mucosa cells in P6 revealed wild-type clones and clones that contained both maternally and paternally inherited mutations, indicating possible somatic reversion which need further investigation since no functional or protein assays were possible for all the patients died and no cell lines were available.

Nijmegen breakage syndrome: clinical characteristics and mutation analysis in eight unrelated Russian families.

OBJECTIVE: The purpose of the study was to ascertain patients with Nijmegen breakage syndrome (NBS) in the Russian population and characterize the clinical phenotype and molecular genotype of these patients. STUDY DESIGN: Eight unrelated Russian patients with possible diagnoses of NBS were identified. Family histories were collected and clinical and laboratory analyses were carried out. Mutation screening of the NBS1 gene was carried out to confirm the diagnosis in 7 cases. RESULTS: All patients had the key diagnostic features of NBS. One patient had acute myeloblastic leukemia (AML). Two patients had bone marrow aplasia, not previously described as a feature of NBS. Mutation screening of the NBS1 gene revealed that 6 patients were homozygous for the 657del5 mutation, whereas a seventh patient was a compound heterozygote, having the 657del5 mutation and an additional novel mutation, 681delT. CONCLUSIONS: Molecular analyses confirmed the diagnosis of NBS in 7 of the patients. The surprising finding of bone marrow aplasia or AML in 3 of 7 patients raises the possibility of a connection between NBS and another DNA damage disorder, Fanconi anemia.

Eleven Polish patients with microcephaly, immunodeficiency, and chromosomal instability: the Nijmegen breakage syndrome.

We report on 11 patients from 8 independent families (3 pairs of sibs) with a complex clinical pattern including microcephaly, peculiar "bird-like" face, growth retardation, and, in some cases, mild-to-moderate mental deficiency. Most of the patients have recurring respiratory tract infections. One girl has developed B-cell lymphoma. A detailed anthropometric study of 15 physical parameters, including 3 cephalic traits, was performed. It was possible to study the chromosomes of PHA-stimulated lymphocytes in all of the patients. We found structural aberrations with multiple rearrangements, preferentially involving chromosomes 7 and 14 in a proportion of metaphases in all individuals. Profound humoral and cellular immune defects were observed. Serum AFP levels were within normal range. Radioresistant DNA synthesis was strongly increased in all 8 patients who were hitherto studied in this respect. Our patients fulfill the criteria of the Nijmegen breakage syndrome, which belongs to the growing category of ataxia telangiectasia-related genetic disorders. In light of the increased predisposition to malignancy in this syndrome, an accurate diagnosis is important for the patient.

Encephalopathy of infancy with intracerebral calcification and chronic spinal fluid lymphocytosis--another case of the Aicardi-Goutières syndrome.

Another case of the Aicardi-Goutières syndrome is presented. The female child was diagnosed at 4 months of age, when irritability, lack of fixation and dystonic movements were noted. Also, extensive intracerebral calcification was found on computed tomography. Nuclear magnetic resonance imaging confirmed extensive white matter disease. Repeated examination of the spinal fluid revealed chronic spinal fluid lymphocytosis. This condition belongs to the encephalopathies of infancy with intracranial calcification of genetic aetiology and unknown pathogenesis. Differentiation against other presumed entities in this group, as well as the wider differential diagnosis, are discussed.