Variable phenotype in 16p duplication within a family

Background More individuals are now being identified with very rare genetic syndromes. We present a family with an inherited duplication of 16p11.2 to 16q12.1 in ring formation. Three of the four children, (aged 15 months to 10 years), mother, uncle, and grandmother are affected. Our aim was to provide preliminary evidence of possible phenotypic patterns of learning and behaviour associated with this chromosome anomaly. Method Psychometric assessments were undertaken with all four children. The mother and uncle also agreed to participate in the study. Measures of development (Bayley or Mullen), intellectual ability (WISC-IV or WAIS-III), academic achievement (WIAT-II), adaptive behaviour (Vinelands), and other relevant aspects of functioning (e.g., Children’s Memory Scale) were administered. Results. The first-born child is the only one who is unaffected. Her intellectual ability was assessed as being within the superior range. The second child experienced early difficulties with speech and motor skills. Although his intelligence is average, he has learning difficulties and significant auditory memory problems. The third child’s speech and motor milestones were markedly delayed. He has a complex medical history that includes a vitamin B12 deficiency. On the Mullen Scales at age 4 his scores ranged from average to very low. The development of the youngest child (aged 15 months), who also had a B12 deficiency but was treated early, was assessed as being within typical limits. Conclusions There is considerable developmental variability among the three children with this inherited 16p duplication. We discuss the intriguing similarities and differences, considering common features that may reflect phenotypic patterns and speculating about possible explanations for the variable presentations.

The role of DNA repair pathways in cisplatin resistant lung cancer

Platinum chemotherapeutic agents such as cisplatin are currently used in the treatment of various malignancies such as lung cancer. However, their efficacy is significantly hindered by the development of resistance during treatment. While a number of factors have been reported that contribute to the onset of this resistance phenotype, alterations in the DNA repair capacity of damaged cells is now recognised as an important factor in mediating this phenomenon. The mode of action of cisplatin has been linked to its ability to crosslink purine bases on the DNA, thereby interfering with DNA repair mechanisms and inducing DNA damage. Following DNA damage, cells respond by activating a DNA-damage response that either leads to repair of the lesion by the cell thereby promoting resistance to the drug, or cell death via activation of the apoptotic response. Therefore, DNA repair is a vital target to improving cancer therapy and reduce the resistance of tumour cells to DNA damaging agents currently used in the treatment of cancer patients. To date, despite the numerous findings that differential expression of components of the various DNA repair pathways correlate with response to cisplatin, translation of such findings in the clinical setting are still warranted. The identification of alterations in specific proteins and pathways that contribute to these unique DNA repair pathways in cisplatin resistant cancer cells may potentially lead to a renewed interest in the development of rational novel therapies for cisplatin resistant cancers, in particular, lung cancer.

Biliverdin modulates the expression of C5aR in response to endotoxin in part via mTOR signaling

Macrophages play a crucial role in the maintenance and resolution of inflammation and express a number of pro- and anti-inflammatory molecules in response to stressors. Among them, the complement receptor 5a (C5aR) plays an integral role in the development of inflammatory disorders. Biliverdin and bilirubin, products of heme catabolism, exert anti-inflammatory effects and inhibit complement activation. Here, we define the effects of biliverdin on C5aR expression in macrophages and the roles of Akt and mammalian target of rapamycin (mTOR) in these responses. Biliverdin administration inhibited lipopolysaccharide (LPS)-induced C5aR expression (without altering basal expression), an effect partially blocked by rapamycin, an inhibitor of mTOR signaling. Biliverdin also reduced LPS-dependent expression of the pro-inflammatory cytokines TNF-alpha and IL-6. Collectively, these data indicate that biliverdin regulates LPS-mediated expression of C5aR via the mTOR pathway, revealing an additional mechanism underlying biliverdin's anti-inflammatory effects.

The effect of osteoimmunomodulation on the osteogenic effects of cobalt incorporated β-tricalcium phosphate

Osteoblast lineage cells are direct effectors of osteogenesis and are, therefore, commonly used to evaluate the in vitro osteogenic capacity of bone substitute materials. This method has served its purposes when testing novel bone biomaterials; however, inconsistent results between in vitro and in vivo studies suggest the mechanisms that govern a material's capacity to mediate osteogenesis are not well understood. The emerging field of osteoimmunology and immunomodulation has informed a paradigm shift in our view of bone biomaterials–from one of an inert to an osteoimmunomodulatory material–highlighting the importance of immune cells in materials-mediated osteogenesis. Neglecting the importance of the immune response during this process is a major shortcoming of the current evaluation protocol. In this study we evaluated a potential angiogenic bone substitute material cobalt incorporated with β-tricalcium phosphate (CCP), comparing the traditional “one cell type” approach with a “multiple cell types” approach to assess osteogenesis, the latter including the use of immune cells. We found that CCP extract by itself was sufficient to enhance osteogenic differentiation of bone marrow stem cells (BMSCs), whereas this effect was cancelled out when macrophages were involved. In response to CCP, the macrophage phenotype switched to the M1 extreme, releasing pro-inflammatory cytokines and bone catabolic factors. When the CCP materials were implanted into a rat femur condyle defect model, there was a significant increase of inflammatory markers and bone destruction, coupled with fibrous encapsulation rather than new bone formation. These findings demonstrated that the inclusion of immune cells (macrophages) in the in vitro assessment matched the in vivo tissue response, and that this method provides a more accurate indication of the essential role of immune cells when assessing materials-stimulated osteogenesis in vitro.

Quantifying the heritability of task-related brain activation and performance during the N-back working memory task: A twin fMRI study

Working memory-related brain activation has been widely studied, and impaired activation patterns have been reported for several psychiatric disorders. We investigated whether variation in N-back working memory brain activation is genetically influenced in 60 pairs of twins, (29 monozygotic (MZ), 31 dizygotic (DZ); mean age 24.4 ± 1.7S.D.). Task-related brain response (BOLD percent signal difference of 2 minus 0-back) was measured in three regions of interest. Although statistical power was low due to the small sample size, for middle frontal gyrus, angular gyrus, and supramarginal gyrus, the MZ correlations were, in general, approximately twice those of the DZ pairs, with non-significant heritability estimates (14-30%) in the low-moderate range. Task performance was strongly influenced by genes (57-73%) and highly correlated with cognitive ability (0.44-0.55). This study, which will be expanded over the next 3 years, provides the first support that individual variation in working memory-related brain activation is to some extent influenced by genes.

Heritability of working memory brain activation

Although key to understanding individual variation in task-related brain activation, the genetic contribution to these individual differences remains largely unknown. Here we report voxel-by-voxel genetic model fitting in a large sample of 319 healthy, young adult, human identical and fraternal twins (mean ± SD age, 23.6 ±1.8 years) who performed an n-back working memory task during functional magnetic resonance imaging (fMRI) at a high magnetic field (4 tesla). Patterns of task-related brain response (BOLD signal difference of 2-back minus 0-back) were significantly heritable, with the highest estimates (40 - 65%) in the inferior, middle, and superior frontal gyri, left supplementary motor area, precentral and postcentral gyri, middle cingulate cortex, superior medial gyrus, angular gyrus, superior parietal lobule, including precuneus, and superior occipital gyri. Furthermore, high test-retest reliability for a subsample of 40 twins indicates that nongenetic variance in the fMRI brain response is largely due to unique environmental influences rather than measurement error. Individual variations in activation of the working memory network are therefore significantly influenced by genetic factors. By establishing the heritability of cognitive brain function in a large sample that affords good statistical power, and using voxel-by-voxel analyses, this study provides the necessary evidence for task-related brain activation to be considered as an endophenotype for psychiatric or neurological disorders, and represents a substantial new contribution to the field of neuroimaging genetics. These genetic brain maps should facilitate discovery of gene variants influencing cognitive brain function through genome-wide association studies, potentially opening up new avenues in the treatment of brain disorders.

Strain- and host species-specific inflammasome activation, IL-1β release, and cell death in macrophages infected with uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is the main etiological agent of urinary tract infections (UTIs). Little is known about interactions between UPEC and the inflammasome, a key innate immune pathway. Here we show that UPEC strains CFT073 and UTI89 trigger inflammasome activation and lytic cell death in human macrophages. Several other UPEC strains, including two multidrug-resistant ST131 isolates, did not kill macrophages. In mouse macrophages, UTI89 triggered cell death only at a high multiplicity of infection, and CFT073-mediated inflammasome responses were completely NLRP3-dependent. Surprisingly, CFT073- and UTI89-mediated responses only partially depended on NLRP3 in human macrophages. In these cells, NLRP3 was required for interleukin-1β (IL-1β) maturation, but contributed only marginally to cell death. Similarly, caspase-1 inhibition did not block cell death in human macrophages. In keeping with such differences, the pore-forming toxin α-hemolysin mediated a substantial proportion of CFT073-triggered IL-1β secretion in mouse but not human macrophages. There was also a more substantial α-hemolysin-independent cell death response in human vs. mouse macrophages. Thus, in mouse macrophages, CFT073-triggered inflammasome responses are completely NLRP3-dependent, and largely α-hemolysin-dependent. In contrast, UPEC activates an NLRP3-independent cell death pathway and an α-hemolysin-independent IL-1β secretion pathway in human macrophages. This has important implications for understanding UTI in humans.

Identification of genetic variants contributing to the migraine phenotype in different Australian populations

This project aimed to identify novel genetic risk variants associated with migraine in the Norfolk Island population. Statistical analysis and bioinformatics approaches such as polygenic modeling and gene clustering methods were carried out to explore genotypic and expression data from high-throughput techniques. This project had a particular focus on hormonal genes and other genetic variants and identified a modest effect size on the migraine phenotype.

Soluble mediators in platelet concentrates modulate dendritic cell inflammatory responses in an experimental model of transfusion

The transfusion of platelet concentrates (PCs) is widely used to treat thrombocytopenia and severe trauma. Ex vivo storage of PCs is associated with a storage lesion characterized by partial platelet activation and the release of soluble mediators, such as soluble CD40 ligand (sCD40L), RANTES, and interleukin (IL)-8. An in vitro whole blood culture transfusion model was employed to assess whether mediators present in PC supernatants (PC-SNs) modulated dendritic cell (DC)-specific inflammatory responses (intracellular staining) and the overall inflammatory response (cytometric bead array). Lipopolysaccharide (LPS) was included in parallel cultures to model the impact of PC-SNs on cell responses following toll-like receptor-mediated pathogen recognition. The impact of both the PC dose (10%, 25%) and ex vivo storage period was investigated [day 2 (D2), day 5 (D5), day 7 (D7)]. PC-SNs alone had minimal impact on DC-specific inflammatory responses and the overall inflammatory response. However, in the presence of LPS, exposure to PC-SNs resulted in a significant dose associated suppression of the production of DC IL-12, IL-6, IL-1a, tumor necrosis factor-a (TNF-a), and macrophage inflammatory protein (MIP)-1b and storage-associated suppression of the production of DC IL-10, TNF-a, and IL-8. For the overall inflammatory response, IL-6, TNF-a, MIP-1a, MIP-1b, and inflammatory protein (IP)-10 were significantly suppressed and IL-8, IL-10, and IL-1b significantly increased following exposure to PC-SNs in the presence of LPS. These data suggest that soluble mediators present in PCs significantly suppress DC function and modulate the overall inflammatory response, particularly in the presence of an infectious stimulus. Given the central role of DCs in the initiation and regulation of the immune response, these results suggest that modulation of the DC inflammatory profile is a probable mechanism contributing to transfusion-related complications.

Novel mutations in ACVR1 result in atypical features in two fibrodysplasia ossificans progressiva patients

Fibrodysplasia Ossificans Progressiva (FOP) is a rare, heritable condition typified by progression of extensive ossification within skeletal muscle, ligament and tendon together with defects in skeletal development. The condition is easily diagnosed by the presence of shortened great toes and there is severe advancement of disability with age. FOP has been shown to result from a point mutation (c.617G>A) in the ACVR1 gene in almost all patients reported. Very recently two other mutations have been described in three FOP patients. We present here evidence for two further unique mutations (c.605G>T and c.983G>A) in this gene in two FOP patients with some atypical digit abnormalities and other clinical features. The observation of disparate missense mutations mapped to the GS and kinase domains of the protein supports the disease model of mild kinase activation and provides a potential rationale for phenotypic variation. © 2009 Petrie et al.

Multicentric carpotarsal osteolysis is caused by mutations clustering in the amino-terminal transcriptional activation domain of MAFB

Multicentric carpotarsal osteolysis (MCTO) is a rare skeletal dysplasia characterized by aggressive osteolysis, particularly affecting the carpal and tarsal bones, and is frequently associated with progressive renal failure. Using exome capture and next-generation sequencing in five unrelated simplex cases of MCTO, we identified previously unreported missense mutations clustering within a 51 base pair region of the single exon of MAFB, validated by Sanger sequencing. A further six unrelated simplex cases with MCTO were also heterozygous for previously unreported mutations within this same region, as were affected members of two families with autosomal-dominant MCTO. MAFB encodes a transcription factor that negatively regulates RANKL-induced osteoclastogenesis and is essential for normal renal development. Identification of this gene paves the way for development of novel therapeutic approaches for this crippling disease and provides insight into normal bone and kidney development.

Erratum: Multicentric carpotarsal osteolysis is caused by mutations clustering in the amino-terminal transcriptional activation domain of MAFB

(The American Journal of Human Genetics, 90, 494–501; March 9, 2012) In the published version of this article, the amino acid alteration caused by c.161C>T should have been notated as p.Ser54Leu and not p.Pro54Leu. The wild-type amino acid is incorrectly notated in the main text, in Table 2, and in Figure 4. The authors regret this error. Additionally, The Journal regrets that this erratum, originally requested in 2012, was not published in a timely fashion.

IgE+ B cells are scarce, but allergen-specific B cells with a memory phenotype circulate in patients with allergic rhinitis

Background Despite the critical role of immunoglobulin E (IgE) in allergy, circulating IgE+ B cells are scarce. Here, we describe in patients with allergic rhinitis B cells with a memory phenotype responding to a prototypic aeroallergen. Methods Fifteen allergic rhinitis patients with grass pollen allergy and 13 control subjects were examined. Blood mononuclear cells stained with carboxyfluorescein diacetate succinimidyl ester (CFSE) were cultured with Bahia grass pollen. Proliferation and phenotype were assessed by multicolour flow cytometry. Results In blood of allergic rhinitis patients with high serum IgE to grass pollen, most IgEhi cells were CD123+ HLA-DR- basophils, with IgE for the major pollen allergen (Pas n 1). Both B and T cells from pollen-allergic donors showed higher proliferation to grass pollen than nonallergic donors (P = 0.002, and 0.010, respectively), whereas responses to vaccine antigens and mitogen did not differ between groups. Allergen-driven B cells that divided rapidly (CD19mid CD3- CFSElo) showed higher CD27 (P = 0.008) and lower CD19 (P = 0.004) and CD20 (P = 0.004) expression than B cells that were slow to respond to allergen (CD19hi CD3- CFSEmid). Moreover, rapidly dividing allergen-driven B cells (CD19mid CFSElo CD27hi) showed higher expression of the plasmablast marker CD38 compared with B cells (CD19hi CFSEmid CD27lo) that were slow to divide. Conclusion Patients with pollen allergy but not control donors have a population of circulating allergen-specific B cells with the phenotype and functional properties of adaptive memory B-cell responses. These cells could provide precursors for allergen-specific IgE production upon allergen re-exposure. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The enigma of IgE+ B-cell memory in human subjects

Our understanding of the origin and fate of the IgE-switched B cell has been markedly improved by studies in mouse models. The immediate precursor of the IgE-switched B cell is either a relatively naive nonswitched B cell or a mature IgG-switched B cell. These 2 routes are referred to as the direct and indirect pathways, respectively. IgE responses derived from each pathway differ significantly, largely reflecting the difference in time spent in a germinal center and thus time for clonal expansion, somatic hypermutation, affinity maturation, and acquisition of a memory phenotype. The clinical and therapeutic implications for IgE responses in human subjects are still a matter of debate, largely because the immunization procedures used in the animal models are significantly different from classical atopic sensitization to allergens from pollen and mites. On the basis of the limited information available, it seems likely that these atopic IgE responses are characterized by a relatively low IgG/IgE ratio, low B-cell memory, and modest affinity maturation, which fits well with the direct switching pathway. It is still unresolved how the IgE response evolves to cover a wide epitope repertoire involving many epitopes per allergen, as well as many different allergens from a single allergen source. © 2013 American Academy of Allergy, Asthma & Immunology.