PDF(Pubmed)
Abstract：
BACKGROUND: Recently, an exonic GGC repeat expansion (RE) was identified by long-read genome sequencing in the ZFHX3 gen, causing spinocerebellar ataxia type 4 (SCA4), a dominant form of ataxia with sensory neuropathy. However, the analysis of larger cohorts of patients remained demanding, resulting in a challenge to diagnose patients and leaving the question of anticipation in SCA4 unanswered.
OBJECTIVE: We aimed to develop a GGC repeat test for clinical SCA4 screening and to apply this test to screen two large German SCA pedigrees and samples of unrelated patients collected over the last 25 years.
METHODS: We modulated a commercial GGC-RE kit (Bio-Techne AmplideX® Asuragen® PCR/CE FMR1 Reagents) with ZFHX3-specific primers and adapted PCR conditions. The test was applied to patients and 50 healthy controls to determine the exact repeat number. Clinical data were revised and correlated with the expanded allele sizes and an exploratory analysis of structural MRI was performed.
RESULTS: Repeat size, determined by our protocol for (GGC)n RE analysis shows a strong inverse correlation between repeat length and age at onset and anticipation in subsequent generations. The phenotype also appears to be more strongly expressed in carriers of longer RE. Clinical red flags were slowed saccades, sensory neuropathy and autonomic dysfunction.
CONCLUSIONS: Our protocol enables cost-effective and robust screening for the causative SCA4 RE within ZFHX3. Furthermore, detailed clinical data of our patients gives a more precise view on SCA4, which seems to be more common among patients with ataxia than expected.
OBJECTIVE: We aimed to develop a GGC repeat test for clinical SCA4 screening and to apply this test to screen two large German SCA pedigrees and samples of unrelated patients collected over the last 25 years.
METHODS: We modulated a commercial GGC-RE kit (Bio-Techne AmplideX® Asuragen® PCR/CE FMR1 Reagents) with ZFHX3-specific primers and adapted PCR conditions. The test was applied to patients and 50 healthy controls to determine the exact repeat number. Clinical data were revised and correlated with the expanded allele sizes and an exploratory analysis of structural MRI was performed.
RESULTS: Repeat size, determined by our protocol for (GGC)n RE analysis shows a strong inverse correlation between repeat length and age at onset and anticipation in subsequent generations. The phenotype also appears to be more strongly expressed in carriers of longer RE. Clinical red flags were slowed saccades, sensory neuropathy and autonomic dysfunction.
CONCLUSIONS: Our protocol enables cost-effective and robust screening for the causative SCA4 RE within ZFHX3. Furthermore, detailed clinical data of our patients gives a more precise view on SCA4, which seems to be more common among patients with ataxia than expected.
摘要：
背景：最近，通过ZFHX3基因中的长读基因组测序鉴定了外显子GGC重复扩增（RE），导致脊髓小脑共济失调4型（SCA4），共济失调的一种主要形式，伴有感觉神经病变。然而,对更大的患者队列的分析仍然很苛刻，导致诊断患者面临挑战，并且SCA4中的预期问题未得到回答。
目的：我们旨在开发一种用于临床SCA4筛查的GGC重复测试，并将该测试应用于筛查两个大型德国SCA家系和过去25年收集的无关患者样本。
方法：我们用ZFHX3特异性引物和适应的PCR条件调节了商业GGC-RE试剂盒（Bio-TechneAmplideX®Asuragen®PCR/CEFMR1试剂）。将该测试应用于患者和50名健康对照以确定确切的重复次数。对临床数据进行了修订，并与扩展的等位基因大小相关联，并对结构MRI进行了探索性分析。
结果：重复大小，通过我们的（GGC）nRE分析方案确定，重复长度与发病年龄和后续世代的预期之间存在很强的负相关。表型也似乎在更长RE的携带者中更强烈地表达。临床危险信号是缓慢的扫视，感觉神经病变和自主神经功能障碍。
结论：我们的方案能够对ZFHX3中的致病SCA4RE进行经济有效和可靠的筛查。此外，我们患者的详细临床数据为SCA4提供了更精确的观点,SCA4在共济失调患者中似乎比预期更常见.
目的：我们旨在开发一种用于临床SCA4筛查的GGC重复测试，并将该测试应用于筛查两个大型德国SCA家系和过去25年收集的无关患者样本。
方法：我们用ZFHX3特异性引物和适应的PCR条件调节了商业GGC-RE试剂盒（Bio-TechneAmplideX®Asuragen®PCR/CEFMR1试剂）。将该测试应用于患者和50名健康对照以确定确切的重复次数。对临床数据进行了修订，并与扩展的等位基因大小相关联，并对结构MRI进行了探索性分析。
结果：重复大小，通过我们的（GGC）nRE分析方案确定，重复长度与发病年龄和后续世代的预期之间存在很强的负相关。表型也似乎在更长RE的携带者中更强烈地表达。临床危险信号是缓慢的扫视，感觉神经病变和自主神经功能障碍。
结论：我们的方案能够对ZFHX3中的致病SCA4RE进行经济有效和可靠的筛查。此外，我们患者的详细临床数据为SCA4提供了更精确的观点,SCA4在共济失调患者中似乎比预期更常见.
