不明原因智力低下／脑发育迟滞患儿的拷贝数变异研究

Study of copy number variations in children with unexplained mental retardation/brain development delay

目的运用单核苷酸多态性比较基因组杂交芯片（SNP-aCGH）对智力低下／脑发育迟滞（MR／BD）病例进行全染色体扫描，分析拷贝数异常变化，为明确诊断和遗传咨询提供帮助。探讨SNP-aCGH技术在不明原因MR／BD遗传分子诊断中的应用。方法收纳不明原因MR／BD患儿92例。予SNP-aCGH全染色体扫描，将异常拷贝数结合临床表型关联分析，找到致病区域及致病候选基因。将阳性病例（携带异常拷贝数的病例）与阴性病例在一般临床表型方面予统计学比对分析。结果1．携带拷贝数异常者10例，检出率10．86％。携带亚端粒区异常拷贝者8例，检出率8．70％；携带非亚端粒异常者5例，检出率5．40％。MR／BD相关异常拷贝数累及不同亚端粒区共10个（9p、21q、3p、2p、15q、4p、12p、22q、16p、17p），累及非亚端粒区7个（1p、4q、2p、14q、15q、12q、22q）。其中，不同缺失位点共11个，长度1．05-8．80Mb；不同重复位点8个，长度1．33-31．25Mb。2．诊断9p重复综合征1例，候选基因DOCK8、VLDLR。CRBN基因断裂1例。诊断第5指综合征并15q26．3-qter缺失1例，候选基因SOX11、LINS1。诊断12p13．3微缺失综合征1例，候选基因ELKS、ERC1。诊断22q13．2-qter微缺失1例，候选基因SHANK3。诊断ATR-16综合征合并17p13．3微重复综合征2例，前者主要候选基因HBA1、HBA2、SOX8，后者YWHAE、LIS1。3．阳性病例与阴性病例在生长迟缓、内脏畸形、低出生体质量儿、早产儿方面差异有统计学意义（P均〈0．05）。结论1．本组阳性病例除不同程度的MR／BD外，几乎均伴发育落后，部分伴内脏畸形、低出生体质量儿、早产儿。2．亚端粒区域与MR／BD密切相关，但非亚端粒区域突变可疑致病，有待深入研究。3．SNP-aCGH技术能高分辨地检出拷贝数变异的起始位点，为寻找MR／BD的致病基因有效缩小范围，同时为研究表型与基因型的关联分析、发病机制等提供一个良好的技术。

Objective By using array -based single nneleotide polymorphisms comparative genomic hybri- dization （SNP -aCGH） to detect and fine mapping copy number variations （CNVs） in children with unexplained men- tal retardation/brain development delay（ MR/BD）, then the CNVs were analyzed to determine diagnosis and offer ge- netic counseling, finally to discuss the application of SNP - aCGH in genetic diagnosis of MR/BD with unknown cau- ses. Methods Ninety - two children with unexplained MR/BD were recruited. SNP - aCGH was used to get CNVs from the whole genome - wide, and the correlation of CNVs and phenotype was analyzed to definit disease genes or pat- hogenic fragment. Statistics was performed to analyze the common phenotype between positive cases （case with CNVs） and negative cases. Results （ 1 ） The CNVs were detected in 10 cases with a detection rate of 10.86% ,from which 8 cases showed subtelomeric aberration,5 cases without subtelomeric aberration, and the rate was 8.70% ,5.40% , re- spectively. The CNVs related to MR/BD involved 10 different subtelomerie regions （9p ,21 q ,3p ,2p, 15q ,4p, 12p ,22q, 16p, 17p） ,and 7 different regions without subtelomeric （ 1p, 4q, 2p, 14q, 15q, 12q, 22q）. The deletions involved 11 zones （ size ： 1.05 - 8.80 Mb）, and duplications referred to 8 zones （ size ： 1.33 - 31.25 Mb）. （2） One case was diag- nosed as 9p duplication syndrome, for candidate genes ： DOCK8, VLDLR. A case was detected with a gene fracture （CRBN）. One case was diagnosed as Coffin - Siris syndrome combined with a deletion of 15q26.3 - qter,for candidate genes：SOX11 and LINS1, respectively. One case referred to 12p13.3 deletion syndrome, for candidate genes：ELKS, ERC1. One case referred to 22q13.2 -qter deletion, for candidate genes： SHANK3. Two cases were diagnosed as ATR-16 syndrome with 17p13.3 deletion syndrome, their candidate genes： HBA1, HBA2, SOX8 for the former, Y1VHAE,LIS1 for the latter. （ 3 ） There were statistically significant differences in comparison of positive cases to thenegative ones for growth delay,internal organs deformity,low birth weight infant（LBW） and premature infant（ all P 〈 0.05）. Conclusions （ 1 ） Besides MR/BD in different degrees in all the positive cases, they also showed growth delay, a portion of them with internal organs deformity,low birth weight infant and premature infant. （2） Subtelomeric aberra- tions are related to MR/BD, while the submicroscopic rearrangement in regions without subtelomeric is suspiciously pathogenic, and need to be further studied. （3） SNP - aCGH can fine mapping the region of CNVs by high resolution from the whole genome - wide, which does contribute to limit the zones for finding pathogenic region and candidate genes, as well as to offer a technology platform for investigating about the correlation of phenotype and genes or CNVs.