Α-胎兒蛋白

α-胎兒蛋白（英語：Alpha-Fetoprotein，縮寫AFP；又譯甲種胎儿球蛋白或甲胎蛋白）是一種α-1球蛋白，由胎兒腸胃道、卵黃囊及肝臟分泌，但可經由腎臟排入尿液、羊水，並通過胎盤進入母體血流中。在正常妊娠時，胎兒血清中之胎兒蛋白濃度於12至14週間達到最高，而母體血清中之濃度則於28至32週間達到最高。如果羊水或母體血清中的α-胎兒蛋白超出正常範圍，需考慮胎兒發育異常，例如：神經管缺損、先天性腎病變、腸道閉鎖、死胎、胎兒窘迫等。也就是說，α-胎兒蛋白雖是一項非特異指標，但對於產前評估胎兒健康狀態甚具臨床價值，也是幫助檢查胎兒異常的一項篩檢工具。 許多肝病皆可能伴隨α-胎兒蛋白之升高，因此可作為臨床參考。例如80%-90%的肝細胞癌病人，其血液中的α-胎兒蛋白有升高之現象，故在肝病甚為流行的區域（如臺灣），利用α-胎兒蛋白及超聲波作為高危險群病人篩檢方式，成效良好。再如肝硬化病人當中有些合併有α-胎兒蛋白之升高，這可能代表肝細胞再生的持續進行；但若持續上升則須積極追蹤，找出可能的惡性變化。此外，急慢性肝炎患者血中的α-胎兒蛋白常隨著肝細胞壞死後之再生而升高。其高峰往往在轉氨基的高峰之後；其升高程度間接地反映肝細胞壞死後的再生能力，也因此常被利用作為病理變化及病程預後之參考。 GRCh38: Ensembl release 89: ENSG00000081051 - Ensembl, May 2017 GRCm38: Ensembl release 89: ENSMUSG00000054932 - Ensembl, May 2017 Human PubMed Reference:. National Center for Biotechnology Information, U.S. National Library of Medicine.  Mouse PubMed Reference:. National Center for Biotechnology Information, U.S. National Library of Medicine.  Nahon JL. The regulation of albumin and alpha-fetoprotein gene expression in mammals. Biochimie. 1987, 69 (5): 445–59. PMID 2445387. doi:10.1016/0300-9084(87)90082-4.  Tilghman SM. The structure and regulation of the alpha-fetoprotein and albumin genes. Oxf. Surv. Eukaryot. Genes. 1989, 2: 160–206. PMID 2474300.  Mizejewski GJ. Biological role of alpha-fetoprotein in cancer: prospects for anticancer therapy. Expert Rev Anticancer Ther. 2003, 2 (6): 709–35. PMID 12503217. doi:10.1586/14737140.2.6.709.  Yachnin S, Hsu R, Heinrikson RL, Miller JB. Studies on human alpha-fetoprotein. Isolation and characterization of monomeric and polymeric forms and amino-terminal sequence analysis. Biochim. Biophys. Acta. 1977, 493 (2): 418–28. PMID 70228. doi:10.1016/0005-2795(77)90198-2.  Aoyagi Y, Ikenaka T, Ichida F. Comparative chemical structures of human alpha-fetoproteins from fetal serum and from ascites fluid of a patient with hepatoma. Cancer Res. 1977, 37 (10): 3663–7. PMID 71198.  Aoyagi Y, Ikenaka T, Ichida F. Copper(II)-binding ability of human alpha-fetoprotein. Cancer Res. 1978, 38 (10): 3483–6. PMID 80265.  Aoyagi Y, Ikenaka T, Ichida F. alpha-Fetoprotein as a carrier protein in plasma and its bilirubin-binding ability. Cancer Res. 1979, 39 (9): 3571–4. PMID 89900.  Torres JM, Anel A, Uriel J. Alpha-fetoprotein-mediated uptake of fatty acids by human T lymphocytes. J. Cell. Physiol. 1992, 150 (3): 456–62. PMID 1371512. doi:10.1002/jcp.1041500305.  Greenberg F, Faucett A, Rose E, et al. Congenital deficiency of alpha-fetoprotein. Am. J. Obstet. Gynecol. 1992, 167 (2): 509–11. PMID 1379776.  Bansal V, Kumari K, Dixit A, Sahib MK. Interaction of human alpha fetoprotein with bilirubin. Indian J. Exp. Biol. 1991, 28 (7): 697–8. PMID 1703124.  Pucci P, Siciliano R, Malorni A, et al. Human alpha-fetoprotein primary structure: a mass spectrometric study. Biochemistry. 1991, 30 (20): 5061–6. PMID 1709810. doi:10.1021/bi00234a032.  Liu MC, Yu S, Sy J, et al. Tyrosine sulfation of proteins from the human hepatoma cell line HepG2. Proceedings of the National Academy of Sciences of the United States of America. 1985, 82 (21): 7160–4. PMC 390808 . PMID 2414772. doi:10.1073/pnas.82.21.7160.  Gibbs PE, Zielinski R, Boyd C, Dugaiczyk A. Structure, polymorphism, and novel repeated DNA elements revealed by a complete sequence of the human alpha-fetoprotein gene. Biochemistry. 1987, 26 (5): 1332–43. PMID 2436661. doi:10.1021/bi00379a020.  Sakai M, Morinaga T, Urano Y, et al. The human alpha-fetoprotein gene. Sequence organization and the 5' flanking region. J. Biol. Chem. 1985, 260 (8): 5055–60. PMID 2580830.  Ruoslahti E, Pihko H, Vaheri A, et al. Alpha fetoprotein: structure and expression in man and inbred mouse strains under normal conditions and liver injury. Johns Hopkins Med. J. Suppl. 1975, 3: 249–55. PMID 4138095.  Urano Y, Sakai M, Watanabe K, Tamaoki T. Tandem arrangement of the albumin and alpha-fetoprotein genes in the human genome. Gene. 1985, 32 (3): 255–61. PMID 6085063. doi:10.1016/0378-1119(84)90001-5.  Beattie WG, Dugaiczyk A. Structure and evolution of human alpha-fetoprotein deduced from partial sequence of cloned cDNA. Gene. 1983, 20 (3): 415–22. PMID 6187626. doi:10.1016/0378-1119(82)90210-4.  Morinaga T, Sakai M, Wegmann TG, Tamaoki T. Primary structures of human alpha-fetoprotein and its mRNA. Proceedings of the National Academy of Sciences of the United States of America. 1983, 80 (15): 4604–8. PMC 384092 . PMID 6192439. doi:10.1073/pnas.80.15.4604.