Navon R, Adam A
Department of Human Genetics, Sackler School of Medicine, Tel Aviv University, Israel.
Hum Hered. 1990;40(2):99-104. doi: 10.1159/000153913.
Twenty unrelated people with thermolabile beta-hexosaminidase (Hex) B were identified in random samples of 41,561 adult Israeli Jews whose sera were screened for Hex A levels. Eighteen of them originated from contiguous Middle Eastern countries (n = 1,337) and only 2 were Ashkenazi Jews (n = 38,388). None was found among the screened Moroccan Jews (n = 1,524). The commonly used screening test for detection of Tay-Sachs disease (TSD) carriers is the serum Hex heat inactivation method (HIM), which is based on the assumption that Hex A is the only thermolabile component of Hex; However, in the presence of thermolabile Hex B, HIM could lead to false-negative results. Since TSD is very rare among Mideastern Jews while thermolabile Hex B is very rare among Ashkenazi and Moroccan Jews, it is concluded that at present there is almost no risk of such false-negative results. In order to further reduce this risk it is recommended that screening of people of Mideastern or mixed ancestry be done with HIM in leukocytes rather than in serum or with the specific substrate for Hex A in serum.
在对41561名成年以色列犹太人的血清进行β-己糖胺酶（Hex）A水平筛查的随机样本中，鉴定出20名患有热不稳定β-己糖胺酶（Hex）B的非亲属个体。其中18人来自中东毗邻国家（n = 1337），只有2人是阿什肯纳兹犹太人（n = 38388）。在接受筛查的摩洛哥犹太人（n = 1524）中未发现病例。检测泰-萨克斯病（TSD）携带者常用的筛查试验是血清Hex热灭活法（HIM），该方法基于Hex A是Hex唯一热不稳定成分的假设；然而，在存在热不稳定Hex B的情况下，HIM可能导致假阴性结果。由于TSD在中东犹太人中非常罕见，而热不稳定Hex B在阿什肯纳兹和摩洛哥犹太人中非常罕见，因此得出结论，目前几乎不存在此类假阴性结果的风险。为了进一步降低这种风险，建议对中东或混合血统的人进行筛查时，采用白细胞中的HIM而非血清中的HIM，或者采用血清中Hex A的特异性底物。
