Knight G J, Palomaki G E, Neveux L M, Fodor K K, Haddow J E
Foundation for Blood Research, Scarborough, Maine 04070-0190, USA.
Prenat Diagn. 1998 Mar;18(3):235-45.
Published studies have reached varying conclusions as to the benefit of replacing human chorionic gonadotropin (hCG) measurements with the free beta-subunit of hCG (the free beta-subunit) for Down syndrome screening. One study reports 14 per cent higher detection for the free beta-subunit, while another finds an actual loss in detection. To explore this issue further, we directly compared the screening performance of hCG and the free beta-subunit, alone and in combination with other serum markers, using banked sera obtained prior to amniocentesis and karyotyping. Altogether, 52 Down syndrome and 5065 unaffected pregnancies were studied. Sera were thawed and assayed for hCG and the free beta-subunit over 1 year. At a 5 per cent false-positive rate, the detection rate for hCG in combination with maternal age and alpha-fetoprotein was higher than when the free beta-subunit was substituted (62 versus 57 per cent). Ultrasound dating and adding unconjugated oestriol both increased detection. The present findings, along with those from six case control studies (our re-analysis), indicate that the screening performances of hCG and the free beta-subunit are similar (median change in detection 0, range -8 to +3 per cent). Under optimal sample collection and transportation conditions, laboratories can expect to achieve similar screening performance using either hCG or the free beta-subunit measurements.
关于用游离β-亚基人绒毛膜促性腺激素（游离β-亚基）替代人绒毛膜促性腺激素（hCG）检测用于唐氏综合征筛查的益处，已发表的研究得出了不同结论。一项研究报告称游离β-亚基的检测率高14%，而另一项研究发现检测率实际上有所下降。为了进一步探讨这个问题，我们使用羊膜穿刺术和核型分析前采集的储存血清，直接比较了hCG和游离β-亚基单独及与其他血清标志物联合使用时的筛查性能。总共研究了52例唐氏综合征妊娠和5065例未受影响的妊娠。血清解冻后在1年多的时间里检测hCG和游离β-亚基。在5%的假阳性率下，hCG与母亲年龄和甲胎蛋白联合使用时的检测率高于用游离β-亚基替代时（分别为62%和57%）。超声确定孕周和添加未结合雌三醇均提高了检测率。目前的研究结果，连同六项病例对照研究（我们的重新分析）的结果表明，hCG和游离β-亚基的筛查性能相似（检测率的中位数变化为0，范围为-8%至+3%）。在最佳样本采集和运输条件下，实验室使用hCG或游离β-亚基检测有望获得相似的筛查性能。
