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SLC34A2 gene

solute carrier family 34 member 2

Normal Function

The SLC34A2 gene provides instructions for making a protein called the type IIb sodium-phosphate cotransporter, which plays a role in the regulation of phosphate levels (phosphate homeostasis). Although this protein can be found in several organs and tissues in the body, it is located mainly in the millions of small air sacs (alveoli) in the lungs, specifically in cells called alveolar type II cells. These cells produce and recycle surfactant, which is a mixture of certain phosphate-containing fats (called phospholipids) and proteins that lines the lung tissue and makes breathing easy. The recycling of surfactant releases phosphate into the alveoli. Research suggests that the type IIb sodium-phosphate cotransporter normally helps clear this phosphate.

Health Conditions Related to Genetic Changes

Pulmonary alveolar microlithiasis

At least 18 SLC34A2 gene mutations have been identified in people with pulmonary alveolar microlithiasis, a disorder in which many tiny fragments (microliths) of a compound called calcium phosphate gradually accumulate in the alveoli. These deposits eventually cause widespread lung damage (interstitial lung disease) that leads to breathing problems.

SLC34A2 gene mutations are thought to impair the activity of the type IIb sodium-phosphate cotransporter, resulting in the accumulation of phosphate in the alveoli. The accumulated phosphate forms the microliths that cause the signs and symptoms of pulmonary alveolar microlithiasis.

More About This Health Condition

Other Names for This Gene

  • NAPI-3B
  • NAPI-IIb
  • NPTIIb
  • sodium-dependent phosphate transport protein 2B
  • sodium/phosphate cotransporter 2B
  • solute carrier family 34 (sodium phosphate), member 2
  • solute carrier family 34 (type II sodium/phosphate contransporter), member 2
  • solute carrier family 34 (type II sodium/phosphate cotransporter), member 2
  • type II sodium-dependent phosphate transporter 3b

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Gene and Variant Databases


  • Castellana G, Castellana G, Gentile M, Castellana R, Resta O. Pulmonary alveolar microlithiasis: review of the 1022 cases reported worldwide. Eur Respir Rev. 2015 Dec;24(138):607-20. doi: 10.1183/16000617.0036-2015. Citation on PubMed
  • Corut A, Senyigit A, Ugur SA, Altin S, Ozcelik U, Calisir H, Yildirim Z, Gocmen A, Tolun A. Mutations in SLC34A2 cause pulmonary alveolar microlithiasis and are possibly associated with testicular microlithiasis. Am J Hum Genet. 2006 Oct;79(4):650-6. doi: 10.1086/508263. Epub 2006 Aug 29. Citation on PubMed or Free article on PubMed Central
  • Ferreira Francisco FA, Pereira e Silva JL, Hochhegger B, Zanetti G, Marchiori E. Pulmonary alveolar microlithiasis. State-of-the-art review. Respir Med. 2013 Jan;107(1):1-9. doi: 10.1016/j.rmed.2012.10.014. Epub 2012 Nov 23. Citation on PubMed
  • Forster IC, Hernando N, Biber J, Murer H. Phosphate transporters of the SLC20 and SLC34 families. Mol Aspects Med. 2013 Apr-Jun;34(2-3):386-95. doi: 10.1016/j.mam.2012.07.007. Citation on PubMed
  • Huqun, Izumi S, Miyazawa H, Ishii K, Uchiyama B, Ishida T, Tanaka S, Tazawa R, Fukuyama S, Tanaka T, Nagai Y, Yokote A, Takahashi H, Fukushima T, Kobayashi K, Chiba H, Nagata M, Sakamoto S, Nakata K, Takebayashi Y, Shimizu Y, Kaneko K, Shimizu M, Kanazawa M, Abe S, Inoue Y, Takenoshita S, Yoshimura K, Kudo K, Tachibana T, Nukiwa T, Hagiwara K. Mutations in the SLC34A2 gene are associated with pulmonary alveolar microlithiasis. Am J Respir Crit Care Med. 2007 Feb 1;175(3):263-8. doi: 10.1164/rccm.200609-1274OC. Epub 2006 Nov 9. Citation on PubMed
  • Jonsson AL, Hilberg O, Bendstrup EM, Mogensen S, Simonsen U. SLC34A2 gene mutation may explain comorbidity of pulmonary alveolar microlithiasis and aortic valve sclerosis. Am J Respir Crit Care Med. 2012 Feb 15;185(4):464. doi: 10.1164/ajrccm.185.4.464. No abstract available. Citation on PubMed
  • Mehta K, Dell S, Birken C, Al-Saleh S. Pulmonary Alveolar Microlithiasis. Can Respir J. 2016;2016:4938632. doi: 10.1155/2016/4938632. Epub 2016 Mar 31. Citation on PubMed or Free article on PubMed Central
  • Saito A, McCormack FX. Pulmonary Alveolar Microlithiasis. Clin Chest Med. 2016 Sep;37(3):441-8. doi: 10.1016/j.ccm.2016.04.007. Epub 2016 Jun 24. Citation on PubMed or Free article on PubMed Central
  • Segawa H, Shiozaki Y, Kaneko I, Miyamoto K. The Role of Sodium-Dependent Phosphate Transporter in Phosphate Homeostasis. J Nutr Sci Vitaminol (Tokyo). 2015;61 Suppl:S119-21. doi: 10.3177/jnsv.61.S119. Citation on PubMed
  • Yin X, Wang H, Wu D, Zhao G, Shao J, Dai Y. SLC34A2 Gene mutation of pulmonary alveolar microlithiasis: report of four cases and review of literatures. Respir Med. 2013 Feb;107(2):217-22. doi: 10.1016/j.rmed.2012.10.016. Epub 2012 Nov 17. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.