对α-地中海贫血的筛查主要针对产前咨询和新生儿筛查诊断。
遗传咨询和妊娠试验
对于有相关种族背景(如:中国人、中国台湾人、东南亚人、地中海沿岸国家的居民)[44]Ryan K, Bain BJ, Worthington D, et al; British Committee for Standards in Haematology. Significant haemoglobinopathies: guidelines for screening and diagnosis. Br J Haematol. 2010;149:35-49.http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2009.08054.x/fullhttp://www.ncbi.nlm.nih.gov/pubmed/20067565?tool=bestpractice.com或无铁缺乏的小红细胞症(如:MCV<80 fL;有的权威机构推荐应用 MCV<82 fL 以防漏诊)或低 MCH 值 (<27 pg/细胞) 的[45]Leung TN, Lau TK, Chung T. Thalassaemia screening in pregnancy. Curr Opin Obstet Gynecol. 2005;17:129-134.http://www.ncbi.nlm.nih.gov/pubmed/15758603?tool=bestpractice.com以及有生育打算的患者,都应接受额外的评估和咨询。其父母双亲都应至少接受 FBC 和红细胞指数(RBC、MCV、MCH)检查。对于 MCH 水平<25 pg/细胞的患者,应高度怀疑其有α(0) 变异体。[44]Ryan K, Bain BJ, Worthington D, et al; British Committee for Standards in Haematology. Significant haemoglobinopathies: guidelines for screening and diagnosis. Br J Haematol. 2010;149:35-49.http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2009.08054.x/fullhttp://www.ncbi.nlm.nih.gov/pubmed/20067565?tool=bestpractice.com如果额外的测试显示配偶中的一位携带有α(0) 变异体,则另一位也应该接受基于 DNA 的α-珠蛋白基因测试,以评估其后代患 Hb H、Hb H/康斯坦特斯普瑞或 Hb Bart 胎儿水肿的风险。[11]Lorey F, Cunningham G, Vichinsky EP, et al. Universal newborn screening for Hb H disease in California. Genet Test. 2001;5:93-100.http://www.ncbi.nlm.nih.gov/pubmed/11551109?tool=bestpractice.com筛查时也应检查其他有临床相关性的血红蛋白变异体。[44]Ryan K, Bain BJ, Worthington D, et al; British Committee for Standards in Haematology. Significant haemoglobinopathies: guidelines for screening and diagnosis. Br J Haematol. 2010;149:35-49.http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2009.08054.x/fullhttp://www.ncbi.nlm.nih.gov/pubmed/20067565?tool=bestpractice.com根据已完成的测试,应确保进行关于疾病、特别是新生儿水肿风险、以及母体发病率的讨论。
筛查若可在患者妊娠之前进行则最为理想。如果患者已有身孕,那么应在其妊娠 12 周之前,完成所有的检查程序,[44]Ryan K, Bain BJ, Worthington D, et al; British Committee for Standards in Haematology. Significant haemoglobinopathies: guidelines for screening and diagnosis. Br J Haematol. 2010;149:35-49.http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2009.08054.x/fullhttp://www.ncbi.nlm.nih.gov/pubmed/20067565?tool=bestpractice.com但在有些群体中,尤其是在地中海贫血症患病率较低的地区,这比较困难。在加拿大进行的群组随机试验中,评价了对镰状细胞疾病和地中海贫血产前筛查的效果,仅有少部分女性在妊娠 10 周之前进行了筛查。然而,随后进行了干预,即在妊娠确认咨询时提供检测,筛查率有所提高。[46]Dormandy E, Bryan S, Gulliford MC, et al. Antenatal screening for haemoglobinopathies in primary care: a cohort study and cluster randomised trial to inform a simulation model. The Screening for Haemoglobinopathies in First Trimester (SHIFT) trial. Health Technol Assess. 2010;14:1-160.http://www.journalslibrary.nihr.ac.uk/__data/assets/pdf_file/0004/64642/FullReport-hta14200.pdfhttp://www.ncbi.nlm.nih.gov/pubmed/20416236?tool=bestpractice.com[47]Langlois S, Ford JC, Chitayat D, et al; CCMG Prenatal Diagnosis Committee; SOGC Genetic Committee. Carrier screening for thalassemia and hemoglobinopathies in Canada. J Obstet Gynaecol Can. 2008;30:950-959.http://www.jogc.com/article/S1701-2163(16)32975-9/pdfhttp://www.ncbi.nlm.nih.gov/pubmed/19038079?tool=bestpractice.com[48]Dormandy E, Gulliford M, Bryan S, et al. Effectiveness of earlier antenatal screeningfor sickle cell disease and thalassaemia in primary care: cluster randomised trial. BMJ. 2010;341:c5132.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2950261/?tool=pubmedhttp://www.ncbi.nlm.nih.gov/pubmed/20923841?tool=bestpractice.com
检测妊娠风险的试验包括胚胎植入前的胎儿 DNA 基因检测(此项检查要求行体外受精)、绒毛膜绒毛取样(通常于妊娠第 10 周至 12 周之间实施)、羊膜腔穿刺术(通常于妊娠 15 周之后实施),或者胎儿血采样(于妊娠 18 周后实施)。[49]ACOG Committee on Obstetrics. ACOG practice bulletin no. 78: hemoglobinopathies in pregnancy. Obstet Gynecol. 2007;109:229-237.http://www.ncbi.nlm.nih.gov/pubmed/17197616?tool=bestpractice.com以上试验均为侵入性试验且有胎儿丢失的风险。超声检查是一项新出现的重要无创性检测方法,专门针对有风险妊娠的重型 α 地中海贫血进行检测,可减少有创性检查的需求。[45]Leung TN, Lau TK, Chung T. Thalassaemia screening in pregnancy. Curr Opin Obstet Gynecol. 2005;17:129-134.http://www.ncbi.nlm.nih.gov/pubmed/15758603?tool=bestpractice.com[50]Tongsong T, Wanapirak C, Sirichotiyakul S, et al. Sonographic markers of hemoglobin Bart disease at midpregnancy. J Ultrasound Med. 2004;23:49-55.http://www.ncbi.nlm.nih.gov/pubmed/14756353?tool=bestpractice.com[51]Li X, Zhou Q, Zhang M, et al. Sonographic markers of fetal α-thalassemia major. J Ultrasound Med. 2015;34:197-206.http://www.ncbi.nlm.nih.gov/pubmed/25614392?tool=bestpractice.com[52]Society for Maternal-Fetal Medicine; Norton ME, Chauhan SP, Dashe JS. Society for maternal-fetal medicine (SMFM) clinical guideline #7: nonimmune hydrops fetalis. Am J Obstet Gynecol. 2015;212:127-139.http://www.ajog.org/article/S0002-9378(14)02443-0/fulltexthttp://www.ncbi.nlm.nih.gov/pubmed/25557883?tool=bestpractice.com
新生儿筛查
新生儿筛查有助于对α-地中海贫血进行早期诊断,并且如果需要,对患者进行早期干预治疗。根据在加利福尼亚的对临床典型的α-地中海贫血症的新生儿筛查显示(在后续的确证检查中,新生儿 HPLC 试验发现 Hb Bart>25%),1998 年至 2006 年间的新生儿发病率为 11.1/10 万。[53]Michlitsch J, Azimi M, Hoppe C, et al. Newborn screening for hemoglobinopathies in California. Pediatr Blood Cancer. 2009;52:486-490.http://www.ncbi.nlm.nih.gov/pubmed/19061217?tool=bestpractice.com然而,此项筛查项目并不具有普遍性,例如:在美国,只有少数州对临床典型的α-地中海贫血症进行筛查。[54]Kemper AR, Knapp AA, Metterville DR, et al. Weighing the evidence for newborn
screening for Hemoglobin H disease. J Pediatr. 2011;158:780-783.http://www.ncbi.nlm.nih.gov/pubmed/21167500?tool=bestpractice.com
无症状的有小红细胞症的患者
对于有轻度贫血和小红细胞症的无症状患者,也可进行筛查,从而建立准确的诊断,以避免进行非必要的以及可能给身体带来伤害的铁干预治疗。