{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T05:01:33Z","timestamp":1781154093907,"version":"3.54.1"},"reference-count":27,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T00:00:00Z","timestamp":1781136000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:p>\n                    Activated phosphoinositide 3-kinase \u03b4 syndrome (APDS) is a newly described inborn error of immunity. Heterozygous mutations in the PI3K\u03b4 catalytic subunit p110\u03b4\n                    <jats:italic>(PIK3CD<\/jats:italic>\n                    ) or regulatory subunit p85\u03b1 (\n                    <jats:italic>PIK3R1<\/jats:italic>\n                    ) lead to APDS1 and APDS2, respectively. Clinical manifestations include lymphoproliferation, recurrent respiratory tract infections, herpesvirus infections, enteropathy, elevated IgM, autoimmunity, and increased susceptibility to tumors, particularly lymphoma. Smoldering multiple myeloma (SMM), an asymptomatic clonal plasma cell disorder considered a pre-malignant entity, may progress to symptomatic multiple myeloma (MM) over time. This report describes a young patient with recurrent respiratory tract infections (pneumonia, bronchiectasis, and otitis media), lymphoproliferation, genital herpes, autoimmunity, and elevated serum IgM and IgG levels. Whole-exome sequencing identified a heterozygous\n                    <jats:italic>PIK3CD<\/jats:italic>\n                    gene mutation (c.1002C&amp;gt;G, p.Asn334Lys), and Sanger sequencing confirmed the same mutation in the patient\u2019s son. Bone marrow aspiration and serum immunofixation electrophoresis confirmed monoclonal plasma cell proliferation, supporting a diagnosis of SMM. The patient did not receive targeted therapy. Early genetic sequencing can facilitate timely diagnosis of APDS and improve prognosis. To the best of our knowledge, this is the first reported case of APDS coexisting with SMM.\n                  <\/jats:p>","DOI":"10.3389\/fonc.2026.1859289","type":"journal-article","created":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T04:38:24Z","timestamp":1781152704000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: First occurrence of smoldering multiple myeloma in activated phosphoinositide 3-Kinase \u03b4 syndrome"],"prefix":"10.3389","volume":"16","author":[{"given":"Yanqiu","family":"Li","sequence":"first","affiliation":[{"name":"Department of Hematology, Suining Central Hospital","place":["Suining, Sichuan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Linlin","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Hematopathology, Sichuan Kingmed Center for Clinical Laboratory","place":["Chengdu, Sichuan, 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China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xingli","family":"Jia","sequence":"additional","affiliation":[{"name":"Department of Hematopathology, Sichuan Kingmed Center for Clinical Laboratory","place":["Chengdu, Sichuan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chao","family":"Ding","sequence":"additional","affiliation":[{"name":"Department of Hematology, Suining Central Hospital","place":["Suining, Sichuan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,11]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1126\/science.1243292","article-title":"Phosphoinositide 3-kinase \u03b4 gene mutation predisposes to respiratory infection and airway 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