We report on the molecular etiology of an unusual clinical phenotype associating congenital neutropenia, thrombocytopenia, developmental delay, and hypopigmentation. Using genetic linkage analysis and targeted gene sequencing, we defined a homozygous genomic deletion in AP3B1, the gene encoding the β chain of the adaptor protein-3 (AP-3) complex. The mutation leads to in-frame skipping of exon 15 and thus perturbs proper assembly of the heterotetrameric AP-3 complex. Consequently, trafficking of transmembrane lysosomal proteins is aberrant, as shown for CD63. In basal keratinocytes, the incorporated immature melanosomes were rapidly degraded in large phagolysosomes. Despite distinct ultramorphologic changes suggestive of aberrant vesicular maturation, no functional aberrations were detected in neutrophil granulocytes. However, a comprehensive immunologic assessment revealed that natural killer (NK) and NKT-cell numbers were reduced in AP-3-deficient patients. Our findings extend the clinical and molecular phenotype of human AP-3 deficiency (also known as Hermansky-Pudlak syndrome, type 2) and provide further insights into the role of the AP-3 complex for the innate immune system. (Blood. 2006;108:362-369)

PURPOSE: Rapidly expanding medical literature challenges oncologists seeking targeted cancer therapies. General-purpose large language models (LLMs) lack domain-specific knowledge, limiting their clinical utility. This study introduces the LLM system Medical Evidence Retrieval and Data Integration for Tailored Healthcare (MEREDITH), designed to support treatment recommendations in precision oncology. Built on Google's Gemini Pro LLM, MEREDITH uses retrieval-augmented generation and chain of thought . METHODS: We evaluated MEREDITH on 10 publicly available fictional oncology cases with iterative feedback from a molecular tumor board (MTB) at a major German cancer center. Initially limited to PubMed -indexed literature (draft system), MEREDITH was enhanced to incorporate clinical studies on drug response within the specific tumor type, trial databases, drug approval status, and oncologic guidelines. The MTB provided a benchmark with manually curated treatment recommendations and assessed the clinical relevance of LLM-generated options (qualitative assessment). We measured semantic cosine similarity between LLM suggestions and clinician responses (quantitative assessment). RESULTS: MEREDITH identified a broader range of treatment options (median 4) compared with MTB experts (median 2). These options included therapies on the basis of preclinical data and combination treatments, expanding the treatment possibilities for consideration by the MTB. This broader approach was achieved by incorporating a curated medical data set that contextualized molecular targetability. Mirroring the approach MTB experts use to evaluate MTB cases improved the LLM's ability to generate relevant suggestions. This is supported by high concordance between LLM suggestions and expert recommendations (94.7% for the enhanced system) and a significant increase in semantic similarity from the draft to the enhanced system (from 0.71 to 0.76, P = .01). CONCLUSION: Expert feedback and domain-specific data augment LLM performance. Future research should investigate responsible LLM integration into real-world clinical workflows.

Background: Common variable immunodeficiency (CVID) comprises a heterogeneous group of primary antibody deficiencies with complex clinical and immunological phenotypes. The recent discovery that some CVID patients show monogenic defects in the genes encoding ICOS, TACI or CD19 prompted us to investigate several functional candidate genes in individuals with CVID. Results: The exonic, protein coding regions of the genes encoding: APRIL, BCMA, IL10, IL10Rα, IL10Rβ, IL21, IL21R, and CCL18, were analyzed primarily in familial CVID cases, who showed evidence of genetic linkage to the respective candidate gene loci and CVID families with a recessive pattern of inheritance. Two novel SNPs were identified in exon 5 and exon 8 of the IL21R gene, which segregated with the disease phenotype in one CVID family. Eleven additional SNPs in the genes encoding BCMA, APRIL, IL10, IL10Rα, IL21 and IL21R were observed at similar frequencies as in healthy donors. Conclusion: We were unable to identify obvious disease causing mutations in the protein coding regions of the analyzed genes in the studied cohort.

Intestinal glucocorticoid-refractory (SR) acute (a) graft-versus-host disease (GVHD) causes high non-relapse mortality (NRM) in patients after allogeneic hematopoietic cell transplantation (allo-HCT). Recent preclinical data indicate that acute GVHD causes a loss of intestinal neuroendocrine L-cells leading to reduced levels of glucagon-like peptide-2 (GLP-2). GLP-2 substitution improved GVHD severity and increased Paneth cells and intestinal stem cells in mice. This motivated us to treat patients with refractory intestinal aGHVD using the GLP-2-analogon teduglutide. In this retrospective multicenter survey, 17 patients received teduglutide as salvage-therapy for SR-intestinal aGVHD. The best response (CR or PR) at any time point during and after treatment was 64.7% (11/17) including 41.2% (7/17) CR and 23.5% (4/17) PR. At a median follow-up of 28 weeks after teduglutide 10/17 patients are alive. Most patients experienced an increase of the albumin serum level within 2 months after the first teduglutide dose, including patients who clinically did not respond to teduglutide treatment. No specific teduglutide-related toxicity was observed. Our retrospective analysis suggests that teduglutide is safe and has activity in a fraction of patients with intestinal SR-aGVHD, which needs validation in a prospective trial.