Biochemical characterization of two novel mutations in the human high-affinity choline transporter 1 identified in a patient with congenital myasthenic syndrome.

Congenital myasthenic syndrome (CMS) is a heterogeneous condition associated with 34 different genes, including SLC5A7, which encodes the high-affinity choline transporter 1 (CHT1). CHT1 is expressed in presynaptic neurons of the neuromuscular junction where it uses the inward sodium gradient to reuptake choline. Biallelic CHT1 mutations often lead to neonatal lethality, and less commonly to non-lethal motor weakness and developmental delays. Here, we report detailed biochemical characterization of two novel mutations in CHT1, p.I294T and p.D349N, which we identified in an 11-year-old patient with a history of neonatal respiratory distress, and subsequent hypotonia and global developmental delay. Heterologous expression of each CHT1 mutant in human embryonic kidney cells showed two different mechanisms of reduced protein function. The p.I294T CHT1 mutant transporter function was detectable, but its abundance and half-life were significantly reduced. In contrast, the p.D349N CHT1 mutant was abundantly expressed at the cell membrane, but transporter function was absent. The residual function of the p.I294T CHT1 mutant may explain the non-lethal form of CMS in this patient, and the divergent mechanisms of reduced CHT1 function that we identified may guide future functional studies of the CHT1 myasthenic syndrome. Based on these in vitro studies that provided a diagnosis, treatment with cholinesterase inhibitor together with physical and occupational therapy significantly improved the patient's strength and quality of life.

MRM2 variants in families with complex dystonic syndromes: evidence for phenotypic heterogeneity.

BACKGROUND: Dystonia involves repetitive movements and muscle contractions leading to abnormal postures. We investigated patients in two families, DYAF11 and M, exhibiting dystonic or involuntary movement disorders. METHODS: Clinical investigations were performed for all patients. Genetic analyses included genome-wide linkage analysis and exome sequencing followed by Sanger sequencing validation. MRM2-specific transcripts were analysed from participants' blood samples in Family DYAF11 after cloning of gene-specific cDNA. RESULTS: Four affected siblings in Family DYAF11 had progressive dystonic features. Two patients in Family M exhibited a neurodevelopmental disorder accompanied by involuntary movements. In Family DYAF11, linkage was detected to the telomere at chromosome 7p22.3, spanning <2 Mb. Exome sequencing identified a donor splice-site variant, c.8+1G>T in MRM2, which segregated with the phenotype, corresponding to the linkage data since all affected individuals were homozygous while the obligate unaffected carriers were heterozygous for the variant. In the MRM2 c.8+1G>T allele, an aberrant alternative acceptor splice-site located within exon 2 was used in a subset of the transcripts, creating a frameshift in the open reading frame. Exome sequencing in Family M revealed a rare missense variant c.242C>T, p.(Ala81Val), which affected a conserved amino acid. CONCLUSIONS: Our results expand the clinical and allelic spectrum of MRM2 variants. Previously, these descriptions were based on observations in a single patient, diagnosed with mitochondrial DNA depletion syndrome 17, in whom movement disorder was accompanied by recurrent strokes and epilepsy. We also demonstrate a subset of correctly spliced tt-ag MRM2 transcripts, raising the possibility to develop treatment by understanding the disease mechanism.

De Novo Variants in the ATPase Module of MORC2 Cause a Neurodevelopmental Disorder with Growth Retardation and Variable Craniofacial Dysmorphism.

MORC2 encodes an ATPase that plays a role in chromatin remodeling, DNA repair, and transcriptional regulation. Heterozygous variants in MORC2 have been reported in individuals with autosomal-dominant Charcot-Marie-Tooth disease type 2Z and spinal muscular atrophy, and the onset of symptoms ranges from infancy to the second decade of life. Here, we present a cohort of 20 individuals referred for exome sequencing who harbor pathogenic variants in the ATPase module of MORC2. Individuals presented with a similar phenotype consisting of developmental delay, intellectual disability, growth retardation, microcephaly, and variable craniofacial dysmorphism. Weakness, hyporeflexia, and electrophysiologic abnormalities suggestive of neuropathy were frequently observed but were not the predominant feature. Five of 18 individuals for whom brain imaging was available had lesions reminiscent of those observed in Leigh syndrome, and five of six individuals who had dilated eye exams had retinal pigmentary abnormalities. Functional assays revealed that these MORC2 variants result in hyperactivation of epigenetic silencing by the HUSH complex, supporting their pathogenicity. The described set of morphological, growth, developmental, and neurological findings and medical concerns expands the spectrum of genetic disorders resulting from pathogenic variants in MORC2.

A Founder Mutation in VPS11 Causes an Autosomal Recessive Leukoencephalopathy Linked to Autophagic Defects.

Genetic leukoencephalopathies (gLEs) are a group of heterogeneous disorders with white matter abnormalities affecting the central nervous system (CNS). The causative mutation in ~50% of gLEs is unknown. Using whole exome sequencing (WES), we identified homozygosity for a missense variant, VPS11: c.2536T>G (p.C846G), as the genetic cause of a leukoencephalopathy syndrome in five individuals from three unrelated Ashkenazi Jewish (AJ) families. All five patients exhibited highly concordant disease progression characterized by infantile onset leukoencephalopathy with brain white matter abnormalities, severe motor impairment, cortical blindness, intellectual disability, and seizures. The carrier frequency of the VPS11: c.2536T>G variant is 1:250 in the AJ population (n = 2,026). VPS11 protein is a core component of HOPS (homotypic fusion and protein sorting) and CORVET (class C core vacuole/endosome tethering) protein complexes involved in membrane trafficking and fusion of the lysosomes and endosomes. The cysteine 846 resides in an evolutionarily conserved cysteine-rich RING-H2 domain in carboxyl terminal regions of VPS11 proteins. Our data shows that the C846G mutation causes aberrant ubiquitination and accelerated turnover of VPS11 protein as well as compromised VPS11-VPS18 complex assembly, suggesting a loss of function in the mutant protein. Reduced VPS11 expression leads to an impaired autophagic activity in human cells. Importantly, zebrafish harboring a vps11 mutation with truncated RING-H2 domain demonstrated a significant reduction in CNS myelination following extensive neuronal death in the hindbrain and midbrain. Thus, our study reveals a defect in VPS11 as the underlying etiology for an autosomal recessive leukoencephalopathy disorder associated with a dysfunctional autophagy-lysosome trafficking pathway.

Loss-of-function HDAC8 mutations cause a phenotypic spectrum of Cornelia de Lange syndrome-like features, ocular hypertelorism, large fontanelle and X-linked inheritance.

Cornelia de Lange syndrome (CdLS) is a multisystem genetic disorder with distinct facies, growth failure, intellectual disability, distal limb anomalies, gastrointestinal and neurological disease. Mutations in NIPBL, encoding a cohesin regulatory protein, account for >80% of cases with typical facies. Mutations in the core cohesin complex proteins, encoded by the SMC1A, SMC3 and RAD21 genes, together account for ∼5% of subjects, often with atypical CdLS features. Recently, we identified mutations in the X-linked gene HDAC8 as the cause of a small number of CdLS cases. Here, we report a cohort of 38 individuals with an emerging spectrum of features caused by HDAC8 mutations. For several individuals, the diagnosis of CdLS was not considered prior to genomic testing. Most mutations identified are missense and de novo. Many cases are heterozygous females, each with marked skewing of X-inactivation in peripheral blood DNA. We also identified eight hemizygous males who are more severely affected. The craniofacial appearance caused by HDAC8 mutations overlaps that of typical CdLS but often displays delayed anterior fontanelle closure, ocular hypertelorism, hooding of the eyelids, a broader nose and dental anomalies, which may be useful discriminating features. HDAC8 encodes the lysine deacetylase for the cohesin subunit SMC3 and analysis of the functional consequences of the missense mutations indicates that all cause a loss of enzymatic function. These data demonstrate that loss-of-function mutations in HDAC8 cause a range of overlapping human developmental phenotypes, including a phenotypically distinct subgroup of CdLS.

Mutations in SLC1A4, encoding the brain serine transporter, are associated with developmental delay, microcephaly and hypomyelination.

BACKGROUND: L-serine plays an essential role in neuronal development and function. Although a non-essential amino acid, L-serine must be synthesised within the brain because of its poor permeability by the blood-brain barrier. Within the brain, its synthesis is confined to astrocytes, and its shuttle to neuronal cells is performed by a dedicated neutral amino acid transporter, ASCT1. METHODS AND RESULTS: Using exome analysis we identified the recessive mutations, p.E256K, p.L315fs, and p.R457W, in SLC1A4, the gene encoding ASCT1, in patients with developmental delay, microcephaly and hypomyelination; seizure disorder was variably present. When expressed in a heterologous system, the mutations did not affect the protein level at the plasma membrane but abolished or markedly reduced L-serine transport for p.R457W and p.E256K mutations, respectively. Interestingly, p.E256K mutation displayed a lower L-serine and alanine affinity but the same substrate selectivity as wild-type ASCT1. CONCLUSIONS: The clinical phenotype of ASCT1 deficiency is reminiscent of defects in L-serine biosynthesis. The data underscore that ASCT1 is essential in brain serine transport. The SLC1A4 p.E256K mutation has a carrier frequency of 0.7% in the Ashkenazi-Jewish population and should be added to the carrier screening panel in this community.

DLCO Biologic Quality-Control Findings From a Multi-Center Global Study.

BACKGROUND: The 2017 American Thoracic Society/European Respiratory Society (ATS/ERS) diffusing capacity of the lung for carbon monoxide (DLCO) standards specify a control rule for assessing biologic quality control (BioQC) but have limited guidance on how to establish expected values for control rule variables. This study aimed to determine expected values for DLCO BioQC using coefficient of variation (CV) and compare that the mean ± 2 SD control rule yields the same precision as mean ± 12% of the mean. METHODS: DLCO BioQC data were collected from a multi-center inhaled medication study. This descriptive study spanned 42 months ending in 2018. The annual DLCO CV was based upon 10 DLCO values separated by at least 5 d. The root mean square CV (RMSCV) was computed for each year and Friedman test evaluated within subject annual CV changes. Ninetieth percentile values were computed for annual control rule limits/mean DLCO. RESULTS: Of 217 BioQCs, the study's first year had 168 subjects with fewer in subsequent years. Annual CV values from RMSCV were 5.3, 4.5, and 4.6% in years 1, 2, and 3, respectively. No change was seen in the CV for those subjects with data for all 3 years, n = 24, P = .07. The 90th percentile of measurements 2 SD/mean DLCO were 15, 12.4, and 11% in years 1, 2, and 3, respectively. CONCLUSIONS: A DLCO BioQC CV ≤ 6% is achievable across multiple sites, technologists, and brands of equipment. This CV value assures that measurements for control rule variables emerge from an expected range. A control rule of mean ± 2 SD appeared to yield similar results as the mean ± 12% of the mean rule reported in the 2017 ATS/ERS DLCO standards.

Evaluation of a community-based intervention for youth mental health in rural Ireland.

BACKGROUND: This study aimed to provide information about pathways to care and clinical response to community-based brief interventions for improving youth mental health through evaluating the Mindspace Mayo service. METHODS: Participants were 1,184 individuals aged 12-25 years (Mean = 17.92, SD = 2.66) who engaged with the Mindspace service. Demographic information included gender, age and living situation. The Clinical Outcome in Routine Evaluation (CORE) was used to measure psychological distress before and after attending the Mindspace service between February 2015 and 2022. RESULTS: On average, individuals received six sessions of therapeutic support. Analyses indicated that most referrals were made by either a parent (40%) or self-referral (38%). The most frequent reason for referral was mood and anxiety-related issues. Across the entire sample, reductions in CORE scores were both statistically and clinically significant. Neither the source of the referral nor living situation significantly predicted intervention response. Complexity of issues presented at referral significantly predicted a reduction in psychological distress post-intervention in young people aged over 17 years. CONCLUSIONS: This study highlighted the value of primary care mental health services for young people aged 12-25 years, and underlined the importance of recording electronic data to track referral pathways, reasons for referral and the intervention outcomes over time.

Interleukin-17A induction of angiogenesis, cell migration, and cytoskeletal rearrangement.

OBJECTIVE: To examine the ability of interleukin-17A (IL-17A) to stimulate angiogenesis, cell migration, and cytoskeletal rearrangement. METHODS: The effect of IL-17A on microvascular tube formation and extracellular matrix invasion by human dermal endothelial cells (HDECs) was assessed using Matrigel matrix and Transwell Matrigel invasion chambers. IL-17A-induced growth-related oncogene α (GROα) and monocyte chemotactic protein 1 (MCP-1) production in rheumatoid arthritis synovial fibroblasts (RASFs) and HDECs was measured by enzyme-linked immunosorbent assay. IL-17A-induced migration was assessed using peripheral blood mononuclear cell (PBMC) migration assays and wound-repair scratch assays, with or without anti-GROα and anti-MCP-1 antibodies. Binding of ß1 integrin receptors was assessed using integrin binding assays. Cytoskeletal assembly/disassembly in RASFs and HDECs were assessed by immunofluorescence staining for F-actin. IL-17A-induced cell migration and cytoskeletal disassembly were assessed in the presence of a Rac1 inhibitor (NSC23766). Rac1 activation following IL-17 stimulation in the presence or absence of anti-GROα, anti-MCP-1, or IgG control was assessed by Rac GTPase pull-down assays and Western blotting. RESULTS: IL-17A significantly up-regulated angiogenesis and endothelial cell invasion. It significantly induced GROα and MCP-1 expression in RASFs. Migration of PBMCs, RASFs, and HDECs was induced by IL-17A; these effects were blocked by anti-GROα or anti-MCP-1 antibodies. IL-17A significantly up-regulated ß1 integrin receptor binding and induced cytoskeletal disassembly in RASFs and HDECs. Rac1 activation was directly induced by IL-17A. IL-17A-induced wound repair and actin rearrangement were inhibited by a pharmacologic inhibitor of Rac1 (NSC23766). Anti-GROα or anti-MCP-1 antibodies had no effect on IL-17A-induced Rac1 activation. CONCLUSION: IL-17A induces angiogenesis, cell migration, and cell invasion, all of which are key processes in the pathogenesis of rheumatoid arthritis and ones that are mediated in part through chemokine- and cytoskeleton-dependent pathways.

Variations in FVC and FEV1 Biologic Quality Control Measures in a Global Multi-Center Clinical Trial.

BACKGROUND: Although quality control standards are recommended to ensure accurate test results, the coefficient of variation for the FVC and FEV1 biologic quality control (BioQC) is not specified. The primary aim of this study was to evaluate variations in spirometry BioQCs in a large and diverse cohort of individuals to determine an acceptable standard for the coefficient of variation. METHODS: The FVC and FEV1 biologic control data were secondary analyses from an inhaled medication trial that was conducted over 3 y ending in 2018 that included 114 laboratories. Results were sent to a central repository for expert review. The FVC and FEV1 coefficients of variation were based upon a minimum of 10 spirometry values annually separated by at least 5 d. A second method of computing the coefficient of variation used 10 values within 28 d. Descriptive statistics were computed. Wilcoxon signed-rank tests were conducted to compare whether the median coefficient of variation values between the 2 methods differed, tested at α = 0.05 using SPSS. RESULTS: Of 249 biologic control participants, 170 met the first year's inclusion criteria. The coefficient of variation for the 5-d separated method was < 5% for 94.1% of FVC and 93.5% of FEV1 values in the first year. By year 3, 90% of FVC and FEV1 coefficient of variation values were < 4%. The medians for the 5-d separated and the 28-d measure showed no difference for either FVC coefficient of variation or FEV1 coefficient of variation, Z = -1.764, P = .78, and Z = -0.980, P = .33, respectively. CONCLUSIONS: Interlab biologic control variation values of < 4% for FVC and FEV1 are achievable; however, individual labs should strive to attain lower values. Acceptable coefficients of variation can be achieved within 28 d.

EIF3F-related neurodevelopmental disorder: refining the phenotypic and expanding the molecular spectrum.

BACKGROUND: An identical homozygous missense variant in EIF3F, identified through a large-scale genome-wide sequencing approach, was reported as causative in nine individuals with a neurodevelopmental disorder, characterized by variable intellectual disability, epilepsy, behavioral problems and sensorineural hearing-loss. To refine the phenotypic and molecular spectrum of EIF3F-related neurodevelopmental disorder, we examined independent patients. RESULTS: 21 patients were homozygous and one compound heterozygous for c.694T>G/p.(Phe232Val) in EIF3F. Haplotype analyses in 15 families suggested that c.694T>G/p.(Phe232Val) was a founder variant. All affected individuals had developmental delays including delayed speech development. About half of the affected individuals had behavioral problems, altered muscular tone, hearing loss, and short stature. Moreover, this study suggests that microcephaly, reduced sensitivity to pain, cleft lip/palate, gastrointestinal symptoms and ophthalmological symptoms are part of the phenotypic spectrum. Minor dysmorphic features were observed, although neither the individuals' facial nor general appearance were obviously distinctive. Symptoms in the compound heterozygous individual with an additional truncating variant were at the severe end of the spectrum in regard to motor milestones, speech delay, organic problems and pre- and postnatal growth of body and head, suggesting some genotype-phenotype correlation. CONCLUSIONS: Our study refines the phenotypic and expands the molecular spectrum of EIF3F-related syndromic neurodevelopmental disorder.

Relationship Between Respiratory Muscle Strength, Handgrip Strength, and Muscle Mass in Hospitalized Patients.

BACKGROUND: Minimal information is available to validate measurement of respiratory muscle strength (RMS) in the clinical setting. The purpose of this study was to determine the correlation between maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP) with handgrip strength (HGS) and cross sectional muscle area obtained via diagnostic abdominal computed tomography (CT). MATERIALS AND METHODS: Measures of MIP, MEP, SNIP, and HGS were obtained from individuals that participated in a previously published study; individuals who had an abdominal CT completed with (±)7 days of obtaining RMS measures were included. Both RMS and HGS were measured within 48-72 hours of admission; for RMS, the highest absolute (cm H2 O) and percent predicted values were recorded, and the average of 3 HGS measurements (kg) was documented. Cross-sectional muscle area (cm2 ) at the third lumbar region was recorded. Spearman's correlation coefficient was used to assess the relationship between variables. RESULTS: A total of 35 participants were included. HGS was correlated to absolute MIP (rs = 0.62, rs = 0.61), MEP (rs = 0.74, rs = 0.73), and SNIP (rs = 0.58, rs = 0.54) for males and females, respectively. Crosss-sectional muscle area was correlated with absolute MIP (rs = 0.66), MEP (rs = 0.58), and SNIP (rs = 0.783) for men and absolute SNIP (rs = 0.56) among women. CONCLUSION: Measures of RMS represent a promising assessment of muscle mass and function among hospitalized patients.

Differences in Respiratory Muscle Strength Measures in Well-Nourished and Malnourished Hospitalized Patients.

BACKGROUND: Objective indicators of nutritional status are essential for accurate identification of malnutrition. Previous research has indicated an association between measures of respiratory muscle strength (RMS) and nutritional status. Measurement of RMS-including maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP)-may provide evidence to support the assessment of nutritional status in hospitalized patients. OBJECTIVE: The purpose of this study was to determine whether there was a difference in MIP, MEP, and SNIP between well-nourished and malnourished hospitalized patients. DESIGN: A cross-sectional study was conducted. PARTICIPANTS/SETTING: Patients were screened for eligibility criteria on admission by means of electronic medical records in general medical or surgical units at a tertiary care hospital in Chicago, IL, from January 2016 to January 2017. A total of 140 patients were included for analysis. MAIN OUTCOMES MEASURED: The primary outcome was detection of differences in measures of RMS between malnourished and well-nourished hospitalized patients. Nutritional status was assessed using subjective global assessment and Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition (Academy/ASPEN) criteria recommended to identify malnutrition. The MIP, MEP, and SNIP measures were obtained and reported as absolute values (expressed in centimeters of water) and percent of predicted values. STATISTICAL ANALYSIS: Independent t tests or Mann-Whitney U tests were used to determine differences in RMS measures between patients assessed as well nourished and those assessed as malnourished, depending on normality. RESULTS: Compared with well-nourished patients, malnourished patients identified by subjective global assessment criteria had significantly lower absolute SNIP (73.7±28.7 vs 59.5±27.1 cm H2O, P=0.004) and percent of predicted SNIP (78.6%±26.3% vs 64.8%± 30.0% predicted, P=0.006). Similarly, compared with well-nourished patients when Academy/ASPEN guidelines were used, malnourished individuals had significantly lower absolute SNIP (76.5±28.6 vs 58.3±26.3 cm H2O, P<0.001), percent of predicted SNIP (81.4%±26.4% vs 63.5%±28.7% predicted, P<0.001), absolute MIP (83.5±34.6 vs 71.1±33.6 cm H2O, P=0.05), and absolute MEP (108.7±36.6 vs 94.2±39.9 cm H2O, P=0.04). CONCLUSION: Differences in RMS between well-nourished and malnourished patients were observed when SNIP measures were used. However, there were no differences in MIP and MEP measures. Further research is needed to build on the findings from this study.

A molecular and clinical study of Larsen syndrome caused by mutations in FLNB.

BACKGROUND: Larsen syndrome is an autosomal dominant osteochondrodysplasia characterised by large-joint dislocations and craniofacial anomalies. Recently, Larsen syndrome was shown to be caused by missense mutations or small inframe deletions in FLNB, encoding the cytoskeletal protein filamin B. To further delineate the molecular causes of Larsen syndrome, 20 probands with Larsen syndrome together with their affected relatives were evaluated for mutations in FLNB and their phenotypes studied. METHODS: Probands were screened for mutations in FLNB using a combination of denaturing high-performance liquid chromatography, direct sequencing and restriction endonuclease digestion. Clinical and radiographical features of the patients were evaluated. RESULTS AND DISCUSSION: The clinical signs most frequently associated with a FLNB mutation are the presence of supernumerary carpal and tarsal bones and short, broad, spatulate distal phalanges, particularly of the thumb. All individuals with Larsen syndrome-associated FLNB mutations are heterozygous for either missense or small inframe deletions. Three mutations are recurrent, with one mutation, 5071G-->A, observed in 6 of 20 subjects. The distribution of mutations within the FLNB gene is non-random, with clusters of mutations leading to substitutions in the actin-binding domain and filamin repeats 13-17 being the most common cause of Larsen syndrome. These findings collectively define autosomal dominant Larsen syndrome and demonstrate clustering of causative mutations in FLNB.

The Limb-Girdle Muscular Dystrophies: Is Treatment on the Horizon?

There has been an ever-expanding list of the Limb-Girdle Muscular Dystrophies (LGMD). There are currently 8 subtypes of autosomal dominant (AD) and 26 subtypes of autosomal recessive (AR) LGMD. Despite continued research efforts to conquer this group of genetic neuromuscular disease, patients continue to be treated symptomatically with the aim of prevention or addressing complications. Mouse models have been helpful in clarifying disease pathogenesis as well as strategizing pathways for treatment. Discoveries in translational research as well as molecular therapeutic approaches have kept clinicians optimistic that more promising clinical trials will lead the way to finding the cure for these devastating disorders. It is well known that the challenge for these rare diseases is the ability to assemble adequate numbers of patients for a clinically meaningful trial, but current efforts in developing patient registries have been encouraging. Natural history studies will be essential in establishing and interpreting the appropriate outcome measures for clinical trials. Nevertheless, animal studies continue to be key in providing proof of concept that will be necessary in moving research along. This review will briefly discuss each type of LGMD, highlighting their distinguishing features, then focus on research efforts that have been published in the literature for the past few years, many of which are still in the preclinical trial stage.

Demodex and rosacea revisited.

Demodex mites are part of the vast microbiome living on and within human skin. The interaction of the various microorganisms with the skin plays a key role in the maintenance of homeostasis. The precise role and function of Demodex mites within normal and diseased human skin remains elusive. The emergence of ivermectin as a key therapy for rosacea has refocused interest in the role of Demodex mites in the pathogenesis of this skin disease and the ability of Demodex to modulate the host immune system.

Potocki-Lupski syndrome in conjunction with bilateral clubfoot.

Potocki-Lupski syndrome (PTLS) is a rare chromosomal microduplication syndrome resulting in multiple congenital abnormalities including developmental delays, autistic features, and certain structural anomalies, with cardiovascular being the most common. The phenotype of this contiguous gene duplication syndrome is quite variable and may include musculoskeletal abnormalities. Given the infrequency and novelty of this disorder, full phenotypic characterization of PTLS has not yet been fully elucidated. We present a case of severe bilateral clubfoot in a patient with PTLS. Diagnosis was made by array-based comparative genomic hybridization and confirmed by fluorescence in-situ hybridization. Because clubfoot was also present in an apparently unaffected brother, the presence of PTLS may have acted as a modifier of the phenotype. This report highlights the complex interaction of chromosomal and familial factors that contribute to musculoskeletal birth defects.

Abacavir-reactive memory T cells are present in drug naïve individuals.

BACKGROUND: Fifty-five percent of individuals with HLA-B*57:01 exposed to the antiretroviral drug abacavir develop a hypersensitivity reaction (HSR) that has been attributed to naïve T-cell responses to neo-antigen generated by the drug. Immunologically confirmed abacavir HSR can manifest clinically in less than 48 hours following first exposure suggesting that, at least in some cases, abacavir HSR is due to re-stimulation of a pre-existing memory T-cell population rather than priming of a high frequency naïve T-cell population. METHODS: To determine whether a pre-existing abacavir reactive memory T-cell population contributes to early abacavir HSR symptoms, we studied the abacavir specific naïve or memory T-cell response using HLA-B*57:01 positive HSR patients or healthy controls using ELISpot assay, intra-cellular cytokine staining and tetramer labelling. RESULTS: Abacavir reactive CD8+ T-cell responses were detected in vitro in one hundred percent of abacavir unexposed HLA-B*57:01 positive healthy donors. Abacavir-specific CD8+ T cells from such donors can be expanded from sorted memory, and sorted naïve, CD8+ T cells without need for autologous CD4+ T cells. CONCLUSIONS: We propose that these pre-existing abacavir-reactive memory CD8+ T-cell responses must have been primed by earlier exposure to another foreign antigen and that these T cells cross-react with an abacavir-HLA-B*57:01-endogenous peptide ligand complex, in keeping with the model of heterologous immunity proposed in transplant rejection.

The role of interleukin-17 in immune-mediated inflammatory myopathies and possible therapeutic implications.

The idiopathic inflammatory myopathies are a heterogeneous group of autoimmune muscle disorders with distinct clinical and pathological features and underlying immunopathogenic mechanisms. Traditionally, CD4(+) Th1 cells or CD8(+) cytotoxic effector T cells and type I/II interferons have been primarily implicated in the pathogenesis of the inflammatory myopathies. The presence of IL-17A producing cells in the inflamed muscle tissue of myositis patients and the results of in vitro studies suggest that IL-17A and the Th17 pathway may also have a key role in these diseases. The contribution of IL-17A to other chronic inflammatory and autoimmune diseases has been well established and clinical trials of IL-17A inhibitors are now at an advanced stage. However the precise role of IL-17A in the various forms of myositis and the potential for therapeutic targeting is currently unknown and warrants further investigation.