{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T18:55:00Z","timestamp":1781117700554,"version":"3.54.1"},"reference-count":29,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T00:00:00Z","timestamp":1767830400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Background: Iron-refractory iron deficiency anemia (IRIDA) is a rare hereditary disorder caused by pathogenic variants in TMPRSS6, characterized by microcytic anemia, low circulating iron levels, and inappropriately high hepcidin levels. Although IRIDA is typically an autosomal recessive disorder, some individuals with a monoallelic pathogenic exonic TMPRSS6 variant exhibit the phenotype, suggesting additional contributing factors. The mechanisms underlying monoallelic IRIDA remain unclear, complicating diagnosis. This study aimed to investigate the potential role of non-coding TMPRSS6 variants and polygenic inheritance in monoallelic IRIDA. Methods: We performed full-gene sequencing of TMPRSS6 in a cohort of 27 subjects, including 6 families (7 symptomatic monoallelic, 7 asymptomatic monoallelic, and 4 wild-type subjects) and 9 isolated symptomatic monoallelic subjects. Whole-exome sequencing of other iron-regulating genes was conducted to evaluate polygenic inheritance. Non-coding variants were assessed for inheritance patterns using family segregation analysis, when available, and for pathogenic potential using in silico prediction tools. Results: Sequencing identified 219 non-coding variants, of which 31 (14 trans-inherited and 17 with unknown inheritance) were exclusive to symptomatic subjects. Two trans-inherited variants (rs80140288 (c.229+945C&gt;T) and rs146953827 (c.230-938_230-937del)) were predicted to affect splicing, while two additional variants (rs78987624 (c.-7001G&gt;A) and rs117575523 (c.*503C&gt;G)) were located in regulatory regions (with unknown inheritance). Whole-exome sequencing did not support polygenic involving other iron-regulating genes. Conclusions: This study highlights four candidate non-coding variants that may contribute to IRIDA expression in monoallelic subjects, offering new insights into its genetic basis. Functional validation is required to confirm their role in disease pathogenesis, refine genotype-phenotype correlations, and improve diagnostic accuracy in monoallelic IRIDA.<\/jats:p>","DOI":"10.3390\/genes17010074","type":"journal-article","created":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T12:56:55Z","timestamp":1767877015000},"page":"74","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["TMPRSS6 Non-Coding Variants in the Expression of Iron Refractory Iron Deficiency Anemia in Monoallelic Subjects"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5036-8554","authenticated-orcid":false,"given":"Vera","family":"Hoving","sequence":"first","affiliation":[{"name":"Department of Hematology, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"},{"name":"Radboud Iron Expertise Center, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Albertine E.","family":"Donker","sequence":"additional","affiliation":[{"name":"Radboud Iron Expertise Center, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"},{"name":"Department of Pediatrics, M\u00e1xima Medical Center, De Run 4600, 5504 DB Veldhoven, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roel J. P.","family":"Smeets","sequence":"additional","affiliation":[{"name":"Translational Metabolic Laboratory, Department of Human Genetics, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bert P. W. J.","family":"van den Heuvel","sequence":"additional","affiliation":[{"name":"Translational Metabolic Laboratory, Department of Human Genetics, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2423-2829","authenticated-orcid":false,"given":"Saskia E. M.","family":"Schols","sequence":"additional","affiliation":[{"name":"Department of Hematology, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"},{"name":"Radboud Iron Expertise Center, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1040-9446","authenticated-orcid":false,"given":"Dorine W.","family":"Swinkels","sequence":"additional","affiliation":[{"name":"Radboud Iron Expertise Center, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"},{"name":"Radboud Laboratory for Diagnostics, Department of Laboratory Medicine, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands"},{"name":"Sanquin Blood Bank, Sanquin Diagnostics BV, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1053\/j.seminhematol.2009.06.006","article-title":"Iron-Refractory Iron Deficiency Anemia","volume":"46","author":"Finberg","year":"2009","journal-title":"Semin. Hematol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/bs.vh.2019.01.004","article-title":"Hepcidin and the BMP-SMAD pathway: An unexpected liaison","volume":"110","author":"Silvestri","year":"2019","journal-title":"Vitam. Horm."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"E482","DOI":"10.1002\/ajh.24561","article-title":"Iron refractory iron deficiency anemia: A heterogeneous disease that is not always iron refractory","volume":"91","author":"Donker","year":"2016","journal-title":"Am. J. Hematol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1146\/annurev-med-043021-032816","article-title":"Hepcidin and Iron in Health and Disease","volume":"74","author":"Nemeth","year":"2023","journal-title":"Annu. Rev. Med."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"van der Staaij, H., Donker, A.E., Bakkeren, D.L., Salemans, J., Mignot-Evers, L.A.A., Bongers, M.Y., Dieleman, J.P., Galesloot, T.E., Laarakkers, C.M., and Klaver, S.M. (2022). Transferrin Saturation\/Hepcidin Ratio Discriminates TMPRSS6-Related Iron Refractory Iron Deficiency Anemia from Patients with Multi-Causal Iron Deficiency Anemia. Int. J. Mol. Sci., 23.","DOI":"10.3390\/ijms23031917"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Hoving, V., Korman, S.E., Antonopoulos, P., Donker, A.E., Schols, S.E.M., and Swinkels, D.W. (2022). IRIDA Phenotype in TMPRSS6 Monoallelic-Affected Patients: Toward a Better Understanding of the Pathophysiology. Genes, 13.","DOI":"10.3390\/genes13081309"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1038\/ng.130","article-title":"Mutations in TMPRSS6 cause iron-refractory iron deficiency anemia (IRIDA)","volume":"40","author":"Finberg","year":"2008","journal-title":"Nat. Genet."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1111\/bjh.12147","article-title":"A novel mutation in the CUB sequence of matriptase-2 (TMPRSS6) is implicated in iron-resistant iron deficiency anaemia (IRIDA)","volume":"160","author":"Jaspers","year":"2012","journal-title":"Br. J. Haematol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"668","DOI":"10.1111\/j.1365-2141.2012.09198.x","article-title":"Two novel mutations in the tmprss6 gene associated with iron-refractory iron-deficiency anaemia (irida) and partial expression in the heterozygous form","volume":"158","author":"Pellegrino","year":"2012","journal-title":"Br. J. Haematol."},{"key":"ref_10","unstructured":"Radboudumc (2025, August 22). Reference Values WCX-TOF MS for Serum Hepcidin-25. Available online: https:\/\/www.hepcidinanalysis.com\/provided-service\/reference-values\/."},{"key":"ref_11","unstructured":"Wallis, Y.L., Payne, S.J., Mcanulty, C., Bodmer, D., Sister-mans, E., Robertson, K., Moore, D., Abbs, S.J., Deans, Z.C., and Devereau, A. (2013). Practice Guidelines for the Evaluation of Pathogenicity and the Reporting of Sequence Variants in Clinical Molecular Genetics, The Association for Clinical Genomic Science."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1038\/gim.2015.30","article-title":"Standards and guidelines for the interpretation of sequence variants: A joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology","volume":"17","author":"Richards","year":"2015","journal-title":"Genet. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1186\/s13073-022-01073-3","article-title":"Recommendations for clinical interpretation of variants found in non-coding regions of the genome","volume":"14","author":"Ellingford","year":"2022","journal-title":"Genome Med."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3018","DOI":"10.1182\/blood.2021011338","article-title":"Hemochromatosis classification: Update and recommendations by the BIOIRON Society","volume":"139","author":"Girelli","year":"2022","journal-title":"Blood"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3873","DOI":"10.1182\/blood-2014-01-548776","article-title":"Practice guidelines for the diagnosis and management of microcytic anemias due to genetic disorders of iron metabolism or heme synthesis","volume":"123","author":"Donker","year":"2014","journal-title":"Blood"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1182\/blood-2005-01-0421","article-title":"Congenital dyserythropoietic anemia type I (CDA I): Molecular genetics, clinical appearance, and prognosis based on long-term observation","volume":"107","author":"Heimpel","year":"2006","journal-title":"Blood"},{"key":"ref_17","unstructured":"Adam, M.P., Feldman, J., Mirzaa, G.M., Pagon, R.A., Wallace, S.E., Bean, L.J.H., Gripp, K.W., and Amemiya, A. (2025, August 22). Congenital Dyserythropoietic Anemia Type I, GeneReviews\u00ae, Available online: https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK5313\/."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"706","DOI":"10.1016\/S0140-6736(15)01315-X","article-title":"Haemochromatosis","volume":"388","author":"Powell","year":"2016","journal-title":"Lancet"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1173","DOI":"10.1038\/ng.456","article-title":"Common variants in TMPRSS6 are associated with iron status and erythrocyte volume","volume":"41","author":"Benyamin","year":"2009","journal-title":"Nat. Genet."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.bcmd.2009.09.001","article-title":"Polymorphisms and mutations of human TMPRSS6 in iron deficiency anemia","volume":"44","author":"Beutler","year":"2010","journal-title":"Blood Cells Mol. Dis."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Serre, D., Gurd, S., Ge, B., Sladek, R., Sinnett, D., Harmsen, E., Bibikova, M., Chudin, E., Barker, D.L., and Dickinson, T. (2008). Differential Allelic Expression in the Human Genome: A Robust Approach To Identify Genetic and Epigenetic Cis-Acting Mechanisms Regulating Gene Expression. PLoS Genet., 4.","DOI":"10.1371\/journal.pgen.1000006"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"419","DOI":"10.1111\/cge.13107","article-title":"Mechanisms of Mendelian dominance","volume":"93","author":"Veitia","year":"2018","journal-title":"Clin. Genet."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3895","DOI":"10.1038\/s41467-022-31686-6","article-title":"Loss-of-function, gain-of-function and dominant-negative mutations have profoundly different effects on protein structure","volume":"13","author":"Gerasimavicius","year":"2022","journal-title":"Nat. Commun."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"E1390","DOI":"10.1002\/humu.21243","article-title":"Novel TMPRSS6 mutations associated with iron-refractory iron deficiency anemia (IRIDA)","volume":"31","author":"Totaro","year":"2010","journal-title":"Hum. Mutat."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"3392","DOI":"10.1182\/blood-2017-03-773481","article-title":"A new form of IRIDA due to combined heterozygous mutations of TMPRSS6 and ACVR1A encoding the BMP receptor ALK2","volume":"129","author":"Pagani","year":"2017","journal-title":"Blood"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"864","DOI":"10.1515\/cclm-2018-0783","article-title":"Provisional standardization of hepcidin assays: Creating a traceability chain with a primary reference material, candidate reference method and a commutable secondary reference material","volume":"57","author":"Diepeveen","year":"2019","journal-title":"Clin. Chem. Lab. Med."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Qian, X., Wang, J., Wang, M., Igelman, A.D., Jones, K.D., Li, Y., Wang, K., Goetz, K.E., Birch, D.G., and Yang, P. (2021). Identification of Deep-Intronic Splice Mutations in a Large Cohort of Patients With Inherited Retinal Diseases. Front. Genet., 12.","DOI":"10.3389\/fgene.2021.647400"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1007\/s10545-018-0146-7","article-title":"The functional genomics laboratory: Functional validation of genetic variants","volume":"41","author":"Rodenburg","year":"2018","journal-title":"J. Inherit. Metab. Dis."},{"key":"ref_29","first-page":"1321","article-title":"Functional and Clinical Impact of Novel Tmprss6 Variants in Iron-Refractory Iron-Deficiency Anemia Patients and Genotype\u2013Phenotype Studies","volume":"35","author":"Silvestri","year":"2014","journal-title":"Hum. Mutat."}],"container-title":["Genes"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4425\/17\/1\/74\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,9]],"date-time":"2026-01-09T09:30:13Z","timestamp":1767951013000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4425\/17\/1\/74"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,8]]},"references-count":29,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["genes17010074"],"URL":"https:\/\/doi.org\/10.3390\/genes17010074","relation":{},"ISSN":["2073-4425"],"issn-type":[{"value":"2073-4425","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,8]]}}}