Dandy-Walker malformation associated with heterozygous ZIC1 and ZIC4 deletion: Report of a new patient

We report on a female patient with Dandy-Walker malformation possibly caused by heterozygous loss of ZIC1 and ZIC4. The patient presented with mental retardation, epilepsy, and multiple congenital malformations including spina bifida, mild dysmorphic facial features including, thick eyebrows, broad nose, full lips, macroglossia, and hypoplasia of the cerebellar vermis with enlargement of the fourth ventricle on brain magnetic resonance imaging, which is consistent with Dandy-Walker malformation. A chromosome analysis showed interstitial deletion of chromosome 3q23-q25.1. Fluorescence in situ hybridization (FISH) and microarray-based genomic analysis revealed the heterozygous deletion of ZIC1 and ZIC4 loci on 3q24. Her facial features were not consistent with those observed in blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) involving FOXL2 abnormality. Other deleted genes at 3q23-25.1 might contribute to the dysmorphic facial appearance. A milder phenotype as the Dandy-Walker malformation in our patient supports the idea that modifying loci/genes can influence the development of cerebellar malformation.     

GLI3基因与单纯性马蹄内翻足的关联分析及其突变筛查

目的对GLU基因与单纯性马蹄内翻足进行关联分析和突变筛查，探讨GLU基因与单纯性马蹄内翻足的相关性。方法应用限制性片段长度多态性分析技术，分析84个单纯性马蹄内翻足核心家系中GLI3基因内两个单核苷酸多态（single nucleotide polymorphisms, SNP）位点的基因型，并应用ETDT软伯统计分析各SNP位点基因型与单纯性马蹄内翻足的关联；应用变性梯度凝胶电泳技术对103例单纯性马蹄内翻足患者GLI3基因的第9至12外显子进行突变筛查。结果经ETDT分析，位于GLI3基因第4外显子的cSNP rs846266差异无统计学意义（χ^2=3．3582，P〉0．05）；第14外显子的cSNP rs929387差异有统计学意义（χ^2=7．2466，P〈0．05），在单纯性马蹄内翻足核心家系中存在传递不平衡；发现1例患者及其母亲的第9外显子有108（G→A）的同义点突变。结论GLI3基因与单纯性马蹄内翻足相关，其第9至12外显子可能并非该病的突变热点。     

鋅指转录因子ZIC3在内脏异位中的研究现状及进展

内脏异位是由于左右非对称性发育异常所致,常与胸腹腔器官的异常偏侧化有关。心脏经常受累,且心脏受累的严重程度通常决定其预后效果。内脏异位患者有特征性的心血管畸形、内脏器官的异常排列以及中线结构发育畸形。在内脏异位患者中第一个被发现有突变的基因是编码锌指转录因子的ZIC3。很多研究证实,ZIC3突变可导致X连锁内脏异位,而且在孤立性先心病中也发现了ZIC3的突变。至今,在内脏异位患者中发现有13个ZIC3突变,其中包括无义突变、错义突变、沉默突变、移码突变以及易位突变等。然而,ZIC3基因在内脏异位,特别是伴复杂先心病中的致病机理仍不是很清楚。本文就ZIC3结构、作用、突变以及其在内脏异位伴先心病中的研究现状及存在的问题做一综述。     

神经管畸形患者锌指蛋白ZIC2基因编码区罕见突变的分子遗传分析

目的筛选ZIC2外显子区域基因突变,分析突变对神经管畸形（NTDs）的影响。方法采用病例对照研究方法,收集来自山西省和江苏省苏州市经孕期B超或病理学解剖证实为NTDs的胎儿为NTDs组,以常规体检排除出生缺陷和重大疾病的胎儿和健康成年人为对照组。采用酚-氯仿法抽提基因组DNA,通过PCR扩增ZIC2的3个外显子及邻近的部分内含子序列,扩增产物采用ABI Prism Bigdye system进行测序,对于测序发现的基因突变进行反向测序验证。结果NTDs组163例,对照组576例。在NTDs组中发现一个同义突变c．1140G〉A,未发现错义突变或重复缺失。同义突变c．1140G〉A位于第2外显子,为1例妊娠期37周诊断为枕部脑膜脑膨出的女性胎儿。KEGG数据库分析ZIC2结构发现该同义突变位于ZIC2的一个C2H2锌指结构中。在对照组中未检测到相同突变。结论ZIC2是一个高度保守基因,其编码区不含有与NTDs相关的SNP和罕见突变。     

GLI基因与肢体发育相关性的研究进展

在肢体发育中,Sonic hedgehog(SHH)蛋白作为极化区(the zone of polarizing actiVity,ZPA)的调节因子,发挥着十分重要的作用。然而SHH是如何沿着肢体的前后轴发挥调控作用的还不是很清楚。最近的报道表明SHH主要是通过阻止转录因子GLI3裂解成抑制形式发挥作用,而后者也能够关闭SHH靶基因的表达。GLI基因家族的成员编码含有锌指结构的转录因子,主要对SHH的靶基因发挥调节作用。现就GLI基因在肢体发育中的表达特点及其临床意义进行综述。     

Genetic and Functional Analyses of ZIC3 Variants in Congenital Heart Disease

Mutations in zinc‐finger in cerebellum 3 (ZIC3) result in heterotaxy or isolated congenital heart disease (CHD). The majority of reported mutations cluster in zinc‐finger domains. We previously demonstrated that many of these lead to aberrant ZIC3 subcellular trafficking. A relative paucity of N‐ and C‐terminal mutations has, however, prevented similar analyses in these regions. Notably, an N‐terminal polyalanine expansion was recently identified in a patient with VACTERL, suggesting a potentially distinct function for this domain. Here we report ZIC3 sequencing results from 440 unrelated patients with heterotaxy and CHD, the largest cohort yet examined. Variants were identified in 5.2% of sporadic male cases. This rate exceeds previous estimates of 1% and has important clinical implications for genetic testing and risk‐based counseling. Eight of 11 were novel, including 5 N‐terminal variants. Subsequent functional analyses included four additional reported but untested variants. Aberrant cytoplasmic localization and decreased luciferase transactivation were observed for all zinc‐finger variants, but not for downstream or in‐frame upstream variants, including both analyzed polyalanine expansions. Collectively, these results expand the ZIC3 mutational spectrum, support a higher than expected prevalence in sporadic cases, and suggest alternative functions for terminal mutations, highlighting a need for further study of these domains.     

GLI3基因在单纯性马蹄内翻足发病机制中的作用

目的 探讨GLI3基因与单纯性马蹄内翻足(idiopathic congenital talipes equinovarus,ICTEV)的相关性.方法 应用变性梯度凝胶电泳技术检测GLI3基因编码区的突变.用逆转录-PCR方法研究GLI3基因在1CTEV患者下肢的表达情况.构建ICTEV大鼠模型,应用实时定量PCR、免疫组织化学染色和蛋白质免疫印迹(Western blotting)方法研究Gli3基因在ICTEV模型鼠下肢肌肉组织中的表达.结果 在84例ICTEV患者外周静脉血中未发现GLI3基因第1～8外显子以及第13外显子存在突变.在ICTEV患者及正常人下肢拇长屈肌中均未检测到GLI3基因的表达.不论在mRNA水平还是在蛋白质水平,Gli3基因在ICTEV模型胎鼠下肢组织中的表达均明显高于正常对照胎鼠.结论 GLI3基因的编码区突变可能不是ICTEV发病的主要原因,但GLI3基因的表达异常与马蹄内翻足的发病可能有关.     

GLI3‐related polydactyly: a review

GLI3 mutations are known to be associated with nine syndromes/conditions in which polydactyly is a feature. In this review, the embryology, pathogenesis, and animal models of GLI3‐related polydactyly are discussed first. This is followed by a detailed review of the genotype–phenotype correlations. Based on our review of the literature and our clinical experiences, we recommend viewing GLI3‐related syndromes/conditions as four separate entities; each characterized by a specific pattern of polydactyly. These four entities are: the preaxial polydactyly type IV‐Greig‐acrocallosal spectrum, postaxial polydactyly types A/B, Pallister–Hall syndrome (PHS), and oral‐facial‐digital overlap syndrome. We also provide illustrative clinical examples from our practice including a family with a novel GLI3 mutation causing PHS. The review also introduces the term ‘Forme Fruste’ preaxial polydactyly and gives several conclusions/recommendations including the recommendation to revise the current criteria for the clinical diagnosis of PHS.     

Molecular screening of SHH, ZIC2, SIX3, and TGIF genes in patients with features of holoprosencephaly spectrum: Mutation review and genotype-phenotype correlations

Holoprosencephaly (HPE; 1 out of 16,000 live births; 1 out of 250 conceptuses) is a complex brain malformation resulting from incomplete cleavage of the prosencephalon, affecting both the forebrain and the face. Clinical expressivity is variable, ranging from a single cerebral ventricle and cyclopia to clinically unaffected carriers in familial dominant autosomic HPE. The disease is genetically heterogeneous, but additional environmental agents also contribute to the etiology of HPE. In our cohort of 200 patients, 34 heterozygous mutations were identified, 24 of them being novel ones: 13 out of 17 in the Sonic hedgehog gene (SHH); 4 out of 7 in ZIC2; and 7 out of 8 in SIX3. The two mutations identified in TGIF have already been reported. Novel phenotypes associated with a mutation have been described, such as abnormalities of the pituitary gland and corpus callosum, colobomatous microphthalmia, choanal aperture stenosis, and isolated cleft lip. This study confirms the great genetic heterogeneity of the disease, the important phenotypic variability in HPE families, and the difficulty to establish genotype-phenotype correlations.     

GLI3基因在单纯性马蹄内翻足发生中的调控机制

目的 探讨在单纯性马蹄内翻足发生过程中GLI3基因的凋控机制.方法 构建荧光素酶报告基因表达载体,分析大鼠Gli3基因5′侧翼启动子区域的活性.用P-Match软件预测Gli3基因上游序列中转录因子的结合位点,并通过染色质免疫沉淀实验、凝胶迁移实验验证.用RNA干扰实验以及构建Hoxd13表达载体,观察其在L6细胞中对Gli3基因表达的影响.结果 在大鼠Gli3基因序列的启动子区域发现2个Hoxd13的结合位点,染色质免疫沉淀和凝胶迁移实验证实Hoxd13结合于结合位点2上.Hoxd13表达下调时,Gli3基因表达明显上调.Hoxd13基因表达上调时,Gli3基因则表达下调.结论 在大鼠胚胎肢体发育中,Hoxd13蛋白可能与Gli3基因启动子区的Hoxd13结合位点2结合,调控Gli3的表达.     

Targeted Resequencing of 29 Candidate Genes and Mouse Expression Studies Implicate ZIC3 and FOXF1 in Human VATER/VACTERL Association

The VATER/VACTERL association describes the combination of congenital anomalies including vertebral defects, anorectal malformations, cardiac defects, tracheoesophageal fistula with or without esophageal atresia, renal malformations, and limb defects. As mutations in ciliary genes were observed in diseases related to VATER/VACTERL, we performed targeted resequencing of 25 ciliary candidate genes as well as disease‐associated genes (FOXF1, HOXD13, PTEN, ZIC3) in 123 patients with VATER/VACTERL or VATER/VACTERL‐like phenotype. We detected no biallelic mutation in any of the 25 ciliary candidate genes; however, identified an identical, probably disease‐causing ZIC3 missense mutation (p.Gly17Cys) in four patients and a FOXF1 de novo mutation (p.Gly220Cys) in a further patient. In situ hybridization analyses in mouse embryos between E9.5 and E14.5 revealed Zic3 expression in limb and prevertebral structures, and Foxf1 expression in esophageal, tracheal, vertebral, anal, and genital tubercle tissues, hence VATER/VACTERL organ systems. These data provide strong evidence that mutations in ZIC3 or FOXF1 contribute to VATER/VACTERL.