Reanalysis of RNA sequencing data ends diagnostic odyssey and expands the phenotypic spectrum of congenital titinopathy.

Although next-generation sequencing has enabled diagnoses for many patients with Mendelian disorders, the majority remain undiagnosed. Here, we present a sibling pair who were clinically diagnosed with Escobar syndrome, however targeted gene testing was negative. Exome sequencing (ES), and later genome sequencing (GS), revealed compound heterozygous TTN variants in both siblings, a maternally inherited frameshift variant [(NM_133378.4):c.36812del; p.(Asp12271Valfs*10)], and a paternally inherited missense variant [(NM_133378.4):c.12322G > A; p.(Asp4108Asn)]. This result was considered nondiagnostic due to poor clinical fit and limited pathogenicity evidence for the missense variant of uncertain significance (VUS). Following initial nondiagnostic RNA sequencing (RNAseq) on muscle and further pursuit of other variants detected on the ES/GS, a reanalysis of noncanonical splice sites in the muscle transcriptome identified an out-of-frame exon retraction in TTN, near the known VUS. Interim literature included reports of patients with similar TTN variants who had phenotypic concordance with the siblings, and a diagnosis of a congenital titinopathy was given 4 years after the TTN variants had been initially reported. This report highlights the value of reanalysis of RNAseq with a different approach, expands the phenotypic spectrum of congenital titinopathy and also illustrates how a perceived phenotypic mismatch, and failure to consider known variants, can result in a prolongation of the diagnostic journey.

Outside the fiber: Endomysial stromal and capillary pathology in skeletal muscle may impede infusion therapy in infantile-onset Pompe disease.

The survival of infantile-onset Pompe disease (IOPD) patients has improved dramatically since the introduction of enzyme replacement therapy (ERT) with a1glucosidase alfa. However, long-term IOPD survivors on ERT demonstrate motor deficits indicating that current therapy cannot completely prevent disease progression in skeletal muscle. We hypothesized that in IOPD, skeletal muscle endomysial stroma and capillaries would show consistent changes that could impede the movement of infused ERT from blood to muscle fibers. We retrospectively examined 9 skeletal muscle biopsies from 6 treated IOPD patients using light and electron microscopy. We found consistent ultrastructural endomysial stromal and capillary changes. The endomysial interstitium was expanded by lysosomal material, glycosomes/glycogen, cellular debris, and organelles, some exocytosed by viable muscle fibers and some released on fiber lysis. Endomysial scavenger cells phagocytosed this material. Mature fibrillary collagen was seen in the endomysium, and both muscle fibers and endomysial capillaries showed basal laminar reduplication and/or expansion. Capillary endothelial cells showed hypertrophy and degeneration, with narrowing of the vascular lumen. Ultrastructurally defined stromal and vascular changes likely constitute obstacles to movement of infused ERT from capillary lumen to muscle fiber sarcolemma, contributing to the incomplete efficacy of infused ERT in skeletal muscle. Our observations can inform approaches to overcoming these barriers to therapy.

Cytostatic hypothermia and its impact on glioblastoma and survival.

Patients with glioblastoma (GBM) have limited options and require novel approaches to treatment. Here, we studied and deployed nonfreezing "cytostatic" hypothermia to stunt GBM growth. This growth-halting method contrasts with ablative, cryogenic hypothermia that kills both neoplastic and infiltrated healthy tissue. We investigated degrees of hypothermia in vitro and identified a cytostatic window of 20° to 25°C. For some lines, 18 hours/day of cytostatic hypothermia was sufficient to halt division in vitro. Next, we fabricated an experimental tool to test local cytostatic hypothermia in two rodent GBM models. Hypothermia more than doubled median survival, and all rats that successfully received cytostatic hypothermia survived their study period. Unlike targeted therapeutics that are successful in preclinical models but fail in clinical trials, cytostatic hypothermia leverages fundamental physics that influences biology broadly. It is a previously unexplored approach that could provide an additional option to patients with GBM by halting tumor growth.

Successful Neonatal, Intraoperative Neuromonitoring in the Surgical Correction of a Thoracic Dermal Sinus Tract: Technical Note.

INTRODUCTION: Intraoperative neuromonitoring (IONM) is commonly used during surgery of the spine and spinal cord for early surveillance of iatrogenic injury to the central and peripheral nervous system. However, for infants and young children under 3 years of age, the use of IONM is challenging due to incomplete central and peripheral myelination. CASE PRESENTATION: We report a case of a T4-T6 dermal sinus tract (DST) that was resected on day of life 23, with the successful use of IONM. CONCLUSION: To our knowledge, this is the youngest reported case of the use of IONM in the surgical correction of a DST in a neonatal patient. This case demonstrates the potential efficacy of IONM in neonatal spine surgery and the techniques used to adapt the technology to an immature nervous system.

Somatic variants in diverse genes leads to a spectrum of focal cortical malformations.

Post-zygotically acquired genetic variants, or somatic variants, that arise during cortical development have emerged as important causes of focal epilepsies, particularly those due to malformations of cortical development. Pathogenic somatic variants have been identified in many genes within the PI3K-AKT-mTOR-signalling pathway in individuals with hemimegalencephaly and focal cortical dysplasia (type II), and more recently in SLC35A2 in individuals with focal cortical dysplasia (type I) or non-dysplastic epileptic cortex. Given the expanding role of somatic variants across different brain malformations, we sought to delineate the landscape of somatic variants in a large cohort of patients who underwent epilepsy surgery with hemimegalencephaly or focal cortical dysplasia. We evaluated samples from 123 children with hemimegalencephaly (n = 16), focal cortical dysplasia type I and related phenotypes (n = 48), focal cortical dysplasia type II (n = 44), or focal cortical dysplasia type III (n = 15). We performed high-depth exome sequencing in brain tissue-derived DNA from each case and identified somatic single nucleotide, indel and large copy number variants. In 75% of individuals with hemimegalencephaly and 29% with focal cortical dysplasia type II, we identified pathogenic variants in PI3K-AKT-mTOR pathway genes. Four of 48 cases with focal cortical dysplasia type I (8%) had a likely pathogenic variant in SLC35A2. While no other gene had multiple disease-causing somatic variants across the focal cortical dysplasia type I cohort, four individuals in this group had a single pathogenic or likely pathogenic somatic variant in CASK, KRAS, NF1 and NIPBL, genes previously associated with neurodevelopmental disorders. No rare pathogenic or likely pathogenic somatic variants in any neurological disease genes like those identified in the focal cortical dysplasia type I cohort were found in 63 neurologically normal controls (P = 0.017), suggesting a role for these novel variants. We also identified a somatic loss-of-function variant in the known epilepsy gene, PCDH19, present in a small number of alleles in the dysplastic tissue from a female patient with focal cortical dysplasia IIIa with hippocampal sclerosis. In contrast to focal cortical dysplasia type II, neither focal cortical dysplasia type I nor III had somatic variants in genes that converge on a unifying biological pathway, suggesting greater genetic heterogeneity compared to type II. Importantly, we demonstrate that focal cortical dysplasia types I, II and III are associated with somatic gene variants across a broad range of genes, many associated with epilepsy in clinical syndromes caused by germline variants, as well as including some not previously associated with radiographically evident cortical brain malformations.

Resolution of radiation necrosis with bevacizumab following radiation therapy for primary CNS lymphoma.

IMPORTANCE: Radiation necrosis (RN) is a rare but serious adverse effect following treatment with radiation therapy. No standard of care exists for the management of RN, and efforts to prevent and treat RN are limited by a lack of insight into the pathomechanics and molecular drivers of RN. This case series describes the outcomes of treatment with bevacizumab (BV) in two primary CNS lymphoma (PCNSL) patients who developed symptomatic biopsy-proven RN after whole brain radiation (WBRT) with a stereotactic radiosurgery (SRS) boost. OBSERVATIONS: Patient 1 is a 52 year-old female with PCNSL treated with WBRT followed by an SRS boost. She developed symptomatic biopsy-proven RN, and initial treatment with tocopherol and pentoxifylline was unsuccessful. A 100% clinical and radiographic response was achieved with 4 cycles of BV. Patient 2, a 48 year-old male with PCNSL, presented with seizures and biopsy-proven RN after radiation therapy. Initial empiric treatment with tocopherol and pentoxifylline was unsuccessful. A 100% clinical and radiographic response was achieved with 3 cycles of BV. CONCLUSIONS AND RELEVANCE: Monitoring for RN in patients with PCNSL treated with radiation therapy is warranted. BV is an efficacious treatment and a viable alternative to corticosteroids or surgical intervention.

Case Report: Unusual Aggregation of Different Glomerulopathies in a Family Resolved by Genetic Testing and Reverse Phenotyping.

Glomerular diseases (GDs) are a major cause of chronic kidney disease in children. The conventional approach to diagnosis of GDs includes clinical evaluation and, in most cases, kidney biopsy to make a definitive diagnosis. However, in many cases, clinical presentations of different GDs can overlap, leading to uncertainty in diagnosis and management even after renal biopsy. In this report, we identify a family with clinical diagnoses of postinfectious glomerulonephritis and IgA nephropathy in a parent and two children. Renal biopsies were initially inconclusive; however, genetic testing showed that the two individuals diagnosed at different points with IgA nephropathy carried novel segregating pathogenic variants in COL4A5 gene. We were only able to make the final diagnoses in each of the family members after genetic testing and reverse phenotyping. This case highlights the utility of genetic testing and reverse phenotyping in resolving clinical diagnosis in families with unusual constellations of different glomerulopathies. We propose that clustering of different glomerular disease phenotypes in a family should be an indication for genetic testing followed by reverse phenotyping.

Blockade of the natriuretic peptide clearance receptor attenuates proteinuria in a mouse model of focal segmental glomerulosclerosis.

Glomerular podocytes play a key role in proteinuric diseases. Accumulating evidence suggests that cGMP signaling has podocyte protective effects. The major source of cGMP generation in podocytes is natriuretic peptides. The natriuretic peptide clearance receptor (NPRC) binds and degrades natriuretic peptides. As a result, NPRC inhibits natriuretic peptide-induced cGMP generation. To enhance cGMP generation in podocytes, we blocked natriuretic peptide clearance using the specific NPRC ligand ANP(4-23). We then studied the effects of NPRC blockade in both cultured podocytes and in a mouse transgenic (TG) model of focal segmental glomerulosclerosis (FSGS) created in our laboratory. In this model, a single dose of the podocyte toxin puromycin aminonucleoside (PAN) causes robust albuminuria in TG mice, but only mild disease in non-TG animals. We found that natriuretic peptides protected cultured podocytes from PAN-induced apoptosis, and that ANP(4-23) enhanced natriuretic peptide-induced cGMP generation in vivo. PAN-induced heavy proteinuria in vehicle-treated TG mice, and this increase in albuminuria was reduced by treatment with ANP(4-23). Treatment with ANP(4-23) also reduced the number of mice with glomerular injury and enhanced urinary cGMP excretion, but these differences were not statistically significant. Systolic BP was similar in vehicle and ANP(4-23)-treated mice. These data suggest that: 1. Pharmacologic blockade of NPRC may be useful for treating glomerular diseases such as FSGS, and 2. Treatment outcomes might be improved by optimizing NPRC blockade to inhibit natriuretic peptide clearance more effectively.

Multisite Quality Improvement Study of a Patient-Pathologist Consultation Program.

OBJECTIVES: The aim of this multisite quality improvement study was to evaluate patients' experiences with the patient-centered pathology (PCP) consultation program and to determine whether PCP enhanced their care experience. METHODS: Patients were invited to attend PCP consultations to review their pathology report and slides and have their questions answered by the pathologist privately, with the option to attend the appointment with family members or friends for support. A patient experience questionnaire (PEQ) was administered to patients, who participated voluntarily in the PCP, and survey data were collected and stored in REDCap. Statistical analysis was performed using SAS 9.4 (SAS Institute). RESULTS: Sixty-seven patients (95.5% female) aged 18 to 84 years across 4 institutions completed the PEQ. Overall, 58% and 15.8% of patients had breast and brain tumors, respectively, and 59.7% of tumors were newly diagnosed. Most patients thought it was important for them to learn as much as they could about their health condition. However, the majority of patients reported some degree of difficulty learning about their health condition based on written information, despite 97% having completed high school and/or further education. The majority of patients rated their pathologist as "excellent" across communication metrics. Ultimately, 100% of respondents were satisfied, found their visits to be useful, and would recommend the PCP to other patients. CONCLUSIONS: Patients found that personalized clinical encounters with pathologists improved their understanding of their health condition and their satisfaction with their care experience. Patients thought pathologists communicated respectfully, effectively, and empathetically.

Eosinophilic globules in a classic ependymoma: evidence of a possible secretory role.

A number of neoplasms of the central nervous system can demonstrate diffuse eosinophilic globules, known to be secretory products of the corresponding cell type, but they have not been a salient feature in descriptions of classic ependymoma. Here, we present a case of a posterior fossa ependymoma demonstrating glassy PAS-positive, diastase-resistant, eosinophilic globules with light microscopic and ultrastructural features resembling Reissner fiber, the secretory product of the subcommissural organ. While there has been a single published description of an ependymoma with intra- and extracellular granulofibrillary material suggested to be evidence of secretory differentiation, ours is the first case to demonstrate diffuse eosinophilic globules in an ependymoma. The extent of globules allowed full study by electron microscopy to provide new insight into the secretory material and the surrounding structures. Our findings suggest that neoplastic ependymal cells can recapitulate the secretory capacity of the subcommissural organ.

Irgm1-deficiency leads to myeloid dysfunction in colon lamina propria and susceptibility to the intestinal pathogen Citrobacter rodentium.

IRGM and its mouse orthologue Irgm1 are dynamin-like proteins that regulate vesicular remodeling, intracellular microbial killing, and pathogen immunity. IRGM dysfunction is linked to inflammatory bowel disease (IBD), and while it is thought that defective intracellular killing of microbes underscores IBD susceptibility, studies have yet to address how IRGM/Irgm1 regulates immunity to microbes relevant to intestinal inflammation. Here we find that loss of Irgm1 confers marked susceptibility to Citrobacter rodentium, a noninvasive intestinal pathogen that models inflammatory responses to intestinal bacteria. Irgm1-deficient mice fail to control C. rodentium outgrowth in the intestine, leading to systemic pathogen spread and host mortality. Surprisingly, susceptibility due to loss of Irgm1 function was not linked to defective intracellular killing of C. rodentium or exaggerated inflammation, but was instead linked to failure to remodel specific colon lamina propria (C-LP) myeloid cells that expand in response to C. rodentium infection and are essential for C. rodentium immunity. Defective immune remodeling was most striking in C-LP monocytes, which were successfully recruited to the infected C-LP, but subsequently underwent apoptosis. Apoptotic susceptibility was induced by C. rodentium infection and was specific to this setting of pathogen infection, and was not apparent in other settings of intestinal inflammation. These studies reveal a novel role for Irgm1 in host defense and suggest that deficiencies in survival and remodeling of C-LP myeloid cells that control inflammatory intestinal bacteria may underpin IBD pathogenesis linked to IRGM dysfunction.

Skeletal Muscle Is an Antigen Reservoir in Integrase-Defective Lentiviral Vector-Induced Long-Term Immunity.

We previously developed integrase-defective lentiviral vectors (IDLVs) as an antigen delivery system for inducing strong and prolonged immunity in animal models. Here, we examined the association between persistence of antigen expression and durability of immune response. Following a single intramuscular (i.m.) or subcutaneous (s.c.) injection of IDLV delivering GFP in mice, we evaluated antigen expression and inflammation at the site of injection and persistence of antigen-specific T cells at early and late time points. Durable antigen expression was detected up to 90 days only after i.m. immunization. Mononuclear inflammation was evident soon after IDLV injection in both i.m. and s.c. immunized mice, but remained detectable up to 30 days postinjection only in i.m. immunized mice. Similarly, GFP-specific T cells were more persistent in the i.m. immunized mice. Interestingly, GFP+ muscle fibers were co-expressing major histocompatibility complex (MHC) class I, suggesting that muscle cells are competent for presenting antigens to T cells in vivo. In in vitro experiments, we demonstrated that although both primary myoblasts and myocytes present the antigen to GFP-specific T cells through MHC class I, myoblasts are more resistant to Fas-dependent cytotoxic T lymphocyte (CTL) killing activity. Overall, these data indicate that muscle cells may serve as an antigen reservoir that contributes to the long-term immunity induced by IDLV vaccination.

Knockout of TRPC6 promotes insulin resistance and exacerbates glomerular injury in Akita mice.

Gain-of-function mutations in TRPC6 cause familial focal segmental glomerulosclerosis, and TRPC6 is upregulated in glomerular diseases including diabetic kidney disease. We studied the effect of systemic TRPC6 knockout in the Akita model of type 1 diabetes. Knockout of TRPC6 inhibited albuminuria in Akita mice at 12 and 16 weeks of age, but this difference disappeared by 20 weeks. Knockout of TRPC6 also reduced tubular injury in Akita mice; however, mesangial expansion was significantly increased. Hyperglycemia and blood pressure were similar between TRPC6 knockout and wild-type Akita mice, but knockout mice were more insulin resistant. In cultured podocytes, knockout of TRPC6 inhibited expression of the calcium/calcineurin responsive gene insulin receptor substrate 2 and decreased insulin responsiveness. Insulin resistance is reported to promote diabetic kidney disease independent of blood glucose levels. While the mechanisms are not fully understood, insulin activates both Akt2 and ERK, which inhibits apoptosis signal regulated kinase 1 (ASK1)-p38-induced apoptosis. In cultured podocytes, hyperglycemia stimulated p38 signaling and induced apoptosis, which was reduced by insulin and ASK1 inhibition and enhanced by Akt or ERK inhibition. Glomerular p38 signaling was increased in TRPC6 knockout Akita mice and was associated with enhanced expression of the p38 gene target cyclooxygenase 2. These data suggest that knockout of TRPC6 in Akita mice promotes insulin resistance and exacerbates glomerular disease independent of hyperglycemia.

MULTIPLE PITUITARY ADENOMAS WITH FUNCTIONAL FOLLICLE-STIMULATING HORMONE SECRETION LEADING TO OVARIAN HYPERSTIMULATION SYNDROME.

OBJECTIVE: To present a rare case of multiple pituitary adenomas with a functional follicle-stimulating hormone component leading to ovarian hyperstimulation syndrome. METHODS: We present the clinical, laboratory, imaging, and pathologic findings along with a review of the literature. RESULTS: A 28-year-old female presented with 5 months of amenorrhea and abdominal pain. Physical exam was unremarkable. Labs revealed elevated prolactin (94 ng/mL), elevated estradiol (608 pg/mL), inappropriately normal follicle-stimulating hormone (10.2 mIU/mL), and suppressed luteinizing hormone (0.36 mIU/mL). Transvaginal ultrasound showed numerous large ovarian cysts bilaterally. Brain magnetic resonance imaging showed a 1.2-cm sellar mass. Various medical therapies were not tolerated due to side effects and the patient underwent gross total resection of the sellar mass with marked improvement in her symptoms and blood hormone levels, resumption of menstruation, and shrinkage of the ovarian cysts. Histologic examination revealed 3 separate staining patterns consistent with multiple pituitary adenomas. CONCLUSION: Functioning gonadotroph adenomas are rare and often difficult to diagnose, though in premenopausal women they can lead to the distinct clinical presentation of spontaneous ovarian hyperstimulation syndrome. The favored treatment approach is surgical as it has the highest reported success rate. Recurrence is not uncommon and long-term surveillance is recommended. Given limited data on long-term follow-up, the role of available therapies is not well defined, and further research is needed. To our knowledge, this is the first reported case of multiple pituitary adenomas that included a functional gonadotroph component.

Regulation of cofilin phosphorylation in glomerular podocytes by testis specific kinase 1 (TESK1).

Expression of a constitutively active Rho A (V14Rho) in podocytes in vivo induces albuminuria and foot process (FP) effacement. These effects may be mediated by the Rho A effector Rho kinase (ROK); but inhibition of ROK with Y27632 failed to attenuate albuminuria or FP effacement in V14Rho mice. ROK activates LIM kinases (LIMKs), which phosphorylate and inhibit the actin depolymerizing factor cofilin 1 (CFL1). Sustained phosphorylation of CFL1 is implicated in human nephrotic diseases, but Y27632 did not inhibit phosphorylation of CFL1 in vivo, despite effective ROK inhibition. CFL1 is also phosphorylated by testis-specific kinase 1 (TESK1) on the same serine residue. TESK1 was expressed in podocytes, and, similar to the in vivo situation, Y27632 had little effect on phospho-CFL1 (pCFL1) levels in cultured podocytes. In contrast, Y27632 reduced pCFL1 levels in TESK1 knockout (KO) cells. ROK inhibition enhanced podocyte motility but, the motility promoting effect of Y27632 was absent in TESK1 KO podocytes. Thus, TESK1 regulates podocyte cytoskeletal dynamics in glomerular podocytes and may play an important role in regulating glomerular filtration barrier integrity in glomerular disease processes.

A Diffuse Leptomeningeal Glioneuronal Tumor Without Diffuse Leptomeningeal Involvement: Detailed Molecular and Clinical Characterization.

Prior to their provisional WHO classification as a distinct entity in 2016, diffuse leptomeningeal glioneuronal tumors (DLGNT) were often regarded as diffuse leptomeningeal presentations of oligodendrogliomas or extraventricular neurocytomas. Their classification as a distinct entity partly relies on their pattern of growth, but DLGNTs without radiological leptomeningeal involvement have been described. In a patient with a DLGNT of the spinal cord without evidence of leptomeningeal involvement, we review in depth the clinical course and the histologic and molecular features of the neoplasm, in the context of other reported cases without diffuse leptomeningeal involvement. Our findings highlight the advantages of molecular analysis in making accurate diagnoses on small spinal tissue samples and underline the need for more long-term clinical follow-up of these rare neoplasms to inform treatment decisions.