State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China.
PLoS One. 2011;6(5):e19458. doi: 10.1371/journal.pone.0019458. Epub 2011 May 13.
Leber congenital amaurosis (LCA) is the earliest onset and most severe form of hereditary retinal dystrophy. So far, full spectrum of variations in the 15 genes known to cause LCA has not been systemically evaluated in East Asians. Therefore, we performed comprehensive detection of variants in these 15 genes in 87 unrelated Han Chinese patients with LCA.
METHODOLOGY/PRINCIPAL FINDINGS: The 51 most frequently mutated exons and introns in the 15 genes were selected for an initial scan using cycle sequencing. All the remaining exons in 11 of the 15 genes were subsequently sequenced. Fifty-three different variants were identified in 44 of the 87 patients (50.6%), involving 78 of the 88 alleles (11 homozygous and 56 heterozygous variants). Of the 53 variants, 35 (66%) were novel pathogenic mutations. In these Chinese patients, variants in GUCY2D are the most common cause of LCA (16.1% cases), followed by CRB1 (11.5%), RPGRIP1 (8%), RPE65 (5.7%), SPATA7 (4.6%), CEP290 (4.6%), CRX (3.4%), LCA5 (2.3%), MERTK (2.3%), AIPL1 (1.1%), and RDH12 (1.1%). This differs from the variation spectrum described in other populations. An initial scan of 55 of 215 PCR amplicons, including 214 exons and 1 intron, detected 83.3% (65/78) of the mutant alleles ultimately found in these 87 patients. In addition, sequencing only 9 exons would detect over 50% of the identified variants and require less than 5% of the labor and cost of comprehensive sequencing for all exons.
CONCLUSIONS/SIGNIFICANCE: Our results suggest that specific difference in the variation spectrum found in LCA patients from the Han Chinese and other populations are related by ethnicity. Sequencing exons in order of decreasing risk is a cost-effective way to identify causative mutations responsible for LCA, especially in the context of genetic counseling for individual patients in a clinical setting.
Leber 先天性黑矇（LCA）是遗传性视网膜营养不良中最早发生且最严重的形式。到目前为止，尚未在东亚人群中系统评估已知导致 LCA 的 15 个基因的全部变异谱。因此，我们对 87 名无亲缘关系的汉族 LCA 患者的这 15 个基因中的变异进行了全面检测。
方法/主要发现：选择这 15 个基因中最常突变的 51 个外显子和内含子进行初步测序。随后对 11 个基因中的所有剩余外显子进行测序。在 87 名患者中的 44 名（50.6%）中发现了 53 种不同的变异，涉及 88 个等位基因中的 78 个（11 个纯合子和 56 个杂合子变异）。在这 53 个变异中，35 个（66%）是新的致病性突变。在中国患者中，GUCY2D 变异是导致 LCA 的最常见原因（16.1%的病例），其次是 CRB1（11.5%）、RPGRIP1（8%）、RPE65（5.7%）、SPATA7（4.6%）、CEP290（4.6%）、CRX（3.4%）、LCA5（2.3%）、MERTK（2.3%）、AIPL1（1.1%）和 RDH12（1.1%）。这与其他人群描述的变异谱不同。对包括 214 个外显子和 1 个内含子在内的 215 个 PCR 扩增子的 55 个进行初步扫描，检测到这 87 名患者最终发现的突变等位基因的 83.3%（65/78）。此外，仅对 9 个外显子进行测序，即可检测到超过 50%的鉴定变异，且所需的劳动力和成本不到对所有外显子进行全面测序的 5%。
结论/意义：我们的结果表明，汉族 LCA 患者与其他人群之间变异谱的具体差异与种族有关。按风险递减的顺序对外显子进行测序是一种经济有效的方法，可以识别导致 LCA 的致病突变，尤其是在临床环境中为个别患者进行遗传咨询时。
