Polymorphism in intron 4 of HFE does not compromise haemochromatosis mutation results
Polymorphism in intron 4 of HFE does not compromise haemochromatosis mutation results
复制标题
HFE 内含子 4 的多态性不会影响血色病突变结果
DOI：
10.1038/15452
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发表时间：
1999
期刊：
影响因子：
30.8
通讯作者：
A. Walker
中科院分区：
文献类型：
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作者：
A. Merryweather;J. J. Pointon;J. Shearman;K. Robson;A. Jouanolle;A. Mosser;V. David;J. L. Gall;D. Halsall;T. Elsey;Alison L Kelly;T. Cox;M. Clare;A. Bomford;J. L. Vandwalle;J. Rochette;N. Borot;H. Coppin;M. Roth;E. Ryan;J. Crowe;A. Totaro;P. Gasparini;A. Roetto;C. Camaschella;C. Darke;D. Wallace;K. Saeb;J. Dooley;M. Worwood;A. Walker
在8月份的《自然遗传学》杂志上，Jeffrey等人1描述了HFE中的引物结合位点多态性（G5569 A），在健康筛查组中，该多态性与C282 Y纯合子血色病（HH）的误诊有关。这种多态性在PCR引物2中，通常用于诊断分析，将这种常见的可治疗疾病与其他不太可治疗的综合征区分开来。在一项随机献血者筛选计划（使用多态性引物）中确定的假定C282 Y纯合子中，48%实际上是铁过载风险最小的5569 A/282 Y复合杂合子1。这些假阳性基因型是由目前世界各地广泛使用的试剂产生的，引起了从事血色病临床护理、研究和预防的医生、科学家和政策制定者的关注。为了评估在高风险、铁超载组中的关注需要，我们通过使用替代的非多态性反向引物（5-TACCTCCTCAGGCACTCCT-3）重新扩增，重新评估了来自HH临床转诊中心的221个推定的C282 Y纯合子（使用“多态性”引物2）。这些“纯合子”占我们总血色病诊断转诊的16%。正如铁超载队列的预期，这些转诊患者的转铁蛋白饱和度（58±1.8% sem）和血清铁蛋白（940±150 ng/ml sem）水平升高。此外，假定的C282 Y“纯合子”的转铁蛋白饱和水平显著高于铁超载的非纯合子（79± 4.1%sem对54± 1.8%sem; P< 0.0001）。在221个假定的“纯合子”中，219个是真正的C282 Y纯合子，2个是序列确认的5569 A/282 Y复合杂合子，没有铁过载的临床证据，转铁蛋白饱和度和血清铁蛋白值正常。使用MseI RFLP分析，我们还观察到健康对照组中5569 A等位基因的患病率（33/314，10.5%）显著高于假定的HFE C282 Y纯合子组（2/442，0.45%; P< 0.0001）。这证实了多态性是非常常见的，但它不是在同一个'创始人'染色体上发现的C282 Y突变。相同的对照组含有7%的C282 Y杂合子（一个282 Y/5569 A复合杂合子），没有C282 Y纯合子，与已知的C282 Y突变的高患病率一致。因此，在高风险、铁超载组中，我们发现假阳性HFE基因型测定的频率仅为0.9%，而在低风险、正常献血者组中，假阳性的患病率要高得多（48%）。这种差异可能源于我们的测试组是富含C282 Y的铁超载临床转诊队列（具有较低的5569 A等位基因患病率），而Jeffrey等人的测试组是健康志愿者（具有人群5569 A等位基因患病率）。因此，错误产生C282 Y纯合基因型的主要（但不是唯一）问题是筛选没有铁过载表型证据的低风险受试者。为了消除这一顾虑，过去和未来的临床或研究对象，从低风险（甚至可能是高风险）的群体应基因型与非多态性引物。
In the August issue of Nature Genetics, Jeffrey et al. 1 described a primer binding site polymorphism (G5569A) in HFE which, in a healthy screening group, was associated with a misdiagnosis of C282Y homozygous haemochromatosis (HH). This polymorphism is within the PCR primer2 typically used for the diagnostic assay that distinguishes this common treatable disorder from other, less-treatable syndromes. Of putative C282Y homozygotes identified in a random blood donor screening program (using the polymorphic primers), 48% were actually 5569A/282Y compound heterozygotes at minimal risk for iron overload1. These false-positive genotypes, generated with reagents now widely used throughout the world, are of concern to physicians, scientists and policy-makers engaged in haemochromatosis clinical care, research and prevention. To assess the need for concern in a higher-risk, iron-overloaded group, we have re-evaluated each of the 221 putative C282Y homozygotes (using the ‘polymorphic’primers2) from our HH clinical referral centre by re-amplifying with an alternative, non-polymorphic reverse primer (5–TACCTCCTCAGGCACTCCT–3). These ‘homozygotes’ represent 16% of our total haemochromatosis diagnostic referrals. As expected for an iron-overloaded cohort, these referred patients had elevated levels of transferrin saturation (58±1.8% sem) and serum ferritin (940±150 ng/ml sem). Moreover, the putative C282Y ‘homozygotes’ had significantly higher transferrin saturation levels than the ironoverloaded non-homozygotes (79±4.1% sem versus 54±1.8% sem; P< 0.0001). Of the 221 putative ‘homozygotes’, 219 were true C282Y homozygotes and 2 were sequence-confirmed 5569A/282Y compound heterozygotes without clinical evidence of iron overload and with normal transferrin saturation and serum ferritin values. Using an MseI RFLP assay, we also observed a significantly higher prevalence of the 5569A allele in a group of healthy controls (33/314, 10.5%) compared with that in the putative HFE C282Y homozygous group (2/442, 0.45%; P< 0.0001). This confirms that the polymorphism is very common, but that it is not found on the same ‘founder’chromosome as the C282Y mutation. The same control group contained 7% C282Y heterozygotes (one 282Y/5569A compound heterozygote) and no C282Y homozygotes, consistent with the known high prevalence of the C282Y mutation. In a high-risk, iron-overloaded group, we therefore found only a 0.9% frequency of false-positive HFE genotype determinations, compared with the much higher (48%) prevalence of false positives in a group of low-risk, normal blood donors1. This discrepancy likely stems from our tested group being a C282Y-enriched, iron-overloaded clinical referral cohort (with a lower 5569A allele prevalence) and that of Jeffrey et al. being healthy volunteers (with a population 5569A allele prevalence). The major (but not sole) concern for falsely generating a C282Y homozygous genotype is therefore in screening low-risk subjects without phenotypic evidence of iron overload. To obviate this concern, past and future clinical or research subjects from low-risk (and perhaps even highrisk) groups should be genotyped with non-polymorphic primers.