Publications by authors named "Timothy R Leahy"

The effective transition from pediatric to adult care for individuals with chronic medical conditions should address the medical, psychosocial and educational needs of the cohort. The views and experiences of service users and their families are an integral component of service development. This study sought to evaluate the current provision of transition services from pediatric immunology services to adult immunology services for patients with a diagnosis of an inborn error of immunity at St.

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Ataxia telangiectasia (A-T) (OMIM 208900) is an autosomal recessive multisystem disorder characterised by progressive cerebellar ataxia, telangiectasias, immunodeficiency and a predisposition to malignancy. 'Variant' A-T has later onset of neurological symptoms and slower progression compared with the 'classic' form. A woman presented with short stature in late childhood.

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Article Synopsis
  • The study investigates autoimmune lymphoproliferative syndrome (ALPS) and similar severe conditions characterized by lymphoproliferation and autoimmune cytopenias, aiming to better classify these disorders based on genetic and clinical features.
  • Conducted in Germany with 431 children referred for ALPS evaluation, the study categorized patients based on specific criteria related to lymphoproliferation and associated immune deficiencies, with a median diagnostic age of about 9.8 years.
  • Findings revealed that 55% of enrolled children were diagnosed with ALPS, and genetic assessments helped differentiate ALPS from autoimmune lymphoproliferative syndrome-like diseases, enhancing understanding and classification of these immune disorders.
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Background: Elevated TCRαβCD4CD8 double-negative T cells (DNT) and serum biomarkers help identify FAS mutant patients with autoimmune lymphoproliferative syndrome (ALPS). However, in some patients with clinical features and biomarkers consistent with ALPS, germline or somatic FAS mutations cannot be identified on standard exon sequencing (ALPS-undetermined: ALPS-U).

Objective: We sought to explore whether complex genetic alterations in the FAS gene escaping standard sequencing or mutations in other FAS pathway-related genes could explain these cases.

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Article Synopsis
  • Inborn errors of immunity (IEI) with dysregulated JAK/STAT signaling can lead to immune dysfunction and infections, and while hematopoietic stem cell transplantation (HSCT) is a potential cure, initial outcomes were not promising.
  • This study evaluated the effectiveness of off-label JAK inhibitors (JAKi) as a treatment option for patients with hyperactive JAK/STAT signaling disorders at various European medical centers.
  • Results showed that 87% of patients with STAT1 gain of function and 90% with STAT3 gain of function saw symptom improvement, with mild adverse events reported; a significant portion of patients continued JAKi treatment successfully, and some proceeded to HSCT, achieving a 91%
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MIS-C is a systemic inflammation disorder with poorly characterised immunopathological mechanisms. We compared changes in the systemic immune response in children with MIS-C (n = 12, 5-13 years) to healthy controls (n = 14, 5-15 years). Analysis was done in whole blood treated with LPS.

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Background: Despite widespread use of the mumps vaccine resulting in significant reduction in the incidence of symptomatic mumps infection, large outbreaks continue to occur in highly vaccinated populations.

Objectives: We examined the mumps-specific IgG, IgG subclasses and neutralization titres to the outbreak Genotype G5 and Jeryl Lynn vaccine (Genotype A) mumps strains.

Study Design: Sera from 207 individuals were classified into five distinct cohorts: healthy controls and mumps cases of 5-17 years and 18-25 years, and naturally infected individuals of 50+ years.

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Aim: Our aim was to describe the epidemiology of multisystem inflammatory syndrome in children (MIS-C) in the Republic of Ireland, in the context of all cases of COVID-19 in children, during the first year of the SARS-CoV-2 pandemic.

Methods: Cases of MIS-C were identified by prospective surveillance in Irish hospitals from April 2020 to April 2021. Paediatric COVID-19 cases and outbreaks in schools or childcare facilities were notified to and routinely investigated by Public Health.

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Roifman syndrome is a rare autosomal recessive inherited syndromic immunodeficiency. We wish to add to the available literature by reporting two brothers with clinical, radiological and immunological features of Roifman syndrome, confirmed on whole exome sequencing. We report an excellent response to subcutaneous immunoglobulin therapy in both brothers, reducing infection burden and hospital admissions.

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Current treatment for adenosine deaminase (ADA)-deficient severe combined immunodeficiency (SCID) includes enzyme replacement therapy (ERT), allogeneic hematopoietic stem cell transplant (HSCT), or ex vivo corrected autologous hematopoietic stem cell gene therapy. Historic data show HSCT survival is superior using unconditioned matched sibling and family compared to matched unrelated and haploidentical donors. Recent improvement in HSCT outcomes prompted us to retrospectively examine HSCT survival and long-term graft function in ADA-SCID transplanted at our center.

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Cerebral Palsy (CP) describes a heterogenous group of non-progressive disorders of posture or movement, causing activity limitation, due to a lesion in the developing brain. CP is an umbrella term for a heterogenous condition and is, therefore, descriptive rather than a diagnosis. Each case requires detailed consideration of etiology.

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Infection and persistent inflammation have a prominent role in the pathogenesis of brain injury and cerebral palsy, as well as other conditions associated with prematurity such as bronchopulmonary dysplasia. The NLRP3 inflammasome-interleukin (IL)-1β pathway has been extensively studied in adults and pre-clinical models, improving our understanding of innate immunity and offering an attractive therapeutic target that is already contributing to clinical management in many auto-inflammatory disorders. IL-1 blockade has transformed the course and outcome of conditions such as chronic infantile neurological, cutaneous, articular (CINCA/NOMID) syndrome.

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Jacobsen syndrome is caused by a terminal deletion on the long arm of chromosome 11 and can be associated with immunodeficiency. Patients with Jacobsen syndrome can be predisposed to cutaneous viral infections that are difficult to treat. We report successful use of topical 1% cidofovir as treatment of recalcitrant verruca vulgaris in one patient and molluscum contagiosum in another patient with Jacobsen syndrome.

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A 15-year-old girl presented with gradual-onset dysphonia and dysphagia. Laryngoscopy revealed significant supraglottic airway obstruction with swelling of both the epiglottis and arytenoids. After emergency tracheostomy, biopsy of the epiglottis revealed lymphoid hyperplasia with focal non-necrotising granulomata, leading to a presumed diagnosis of laryngeal sarcoidosis.

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Aim: To review multiorgan involvement and management in children with Down syndrome (DS).

Methods: A literature review of articles from 1980 to 2019 using the MEDLINE interface of PubMed was performed using the following search terms- [Down syndrome] or [Trisomy 21] AND [Cardiology] or [Respiratory] or [neurodevelopment] or [epilepsy] or [musculoskeletal] or [immune system] or [haematological] or [endocrine] or [gastrointestinal] or [ophthalmological] or [Ear Nose Throat] or [dermatology] or [renal].

Results: Congenital heart disease particularly septal defects occur in over 60% of infants with DS and 5%-34% of infants develop persistent pulmonary hypertension of the newborn irrespective of a diagnosis of congenital heart disease.

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Mutations in the coiled-coil and DNA-binding domains of STAT1 lead to delayed STAT1 dephosphorylation and subsequently gain-of-function. The associated clinical phenotype is broad and can include chronic mucocutaneous candidiasis (CMC) and/or combined immunodeficiency (CID). We report a case of CMC/CID in a 10-year-old boy due to a novel mutation in the small ubiquitin molecule (SUMO) consensus site at the C-terminal region of STAT1 leading to gain-of-function by impaired sumoylation.

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STAT1 gain-of-function (GOF) variants lead to defective Th17 cell development and chronic mucocutaneous candidiasis (CMC), but frequently also to autoimmunity. Stimulation of cells with STAT1 inducing cytokines like interferons (IFN) result in hyperphosphorylation and delayed dephosphorylation of GOF STAT1. However, the mechanism how the delayed dephosphorylation exactly causes the increased expression of STAT1-dependent genes, and how the intracellular signal transduction from cytokine receptors is affected, remains unknown.

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Background: Down syndrome (DS) is the most common syndromic immunodeficiency with an increased risk of infection, mortality from sepsis, and autoinflammation. Innate immune function is altered in DS and therefore we examined responses in CD11b and Toll like receptor 4 (TLR-4), which are important immune cell surface markers upregulated in response to Lipopolysaccharide (LPS) endotoxin, and the immunomodulator melatonin. Neutrophil and monocyte responses to LPS and melatonin in children with Down syndrome (DS) who were clinically stable were compared to age-matched controls.

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Premature T-cell immunosenescence with CD57 CD8 T-cell accumulation has been linked to immunodeficiency and autoimmunity in primary immunodeficiencies including activated PI3 kinase delta syndrome (APDS). To address whether CD57 marks the typical senescent T-cell population seen in adult individuals or identifies a distinct population in APDS, we compared CD57 CD8 T cells from mostly pediatric APDS patients to those of healthy adults with similarly prominent senescent T cells. CD57 CD8 T cells from APDS patients were less differentiated with more CD27 CD28 effector memory T cells showing increased PD1 and Eomesodermin expression.

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