Submicroscopic Chromosomal Copy Number Variations Identified in Children With Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS), one of the most severe types of congenital heart disease (CHD), results in significant morbidity and mortality despite surgical palliation. The etiology of HLHS is unknown, but evidence supports genetic contributors. The authors hypothesized that submicroscopic chromosomal abnormalities exist in individuals with HLHS and are more frequent in those with additional birth defects. This study sought to determine the incidence and genomic location of submicroscopic chromosomal abnormalities in HLHS and potentially to identify novel genetic loci that may contribute to the disease. For this study, 43 children with HLHS were recruited and screened together with a control population of 16 subjects using array comparative genomic hybridization, also called chromosomal microarray, for chromosomal copy number variations (CNVs). A statistically greater number of CNVs were found in the HLHS group than in the control group (p < 0.03). The CNVs were predominantly small autosomal deletions and duplications (≤ 60,000 bp). The frequency of unique CNVs, those not previously reported in public databases, did not differ statistically between the HLHS subjects and the control subjects. No difference in the frequency of CNVs was noted between the patients with HLHS and additional anomalies and those with isolated HLHS. The identified CNVs did not harbor potential candidate genes for HLHS, but one microdeletion was located on chromosome 14q23, a genetic locus linked to left-sided CHD. The study data demonstrate that CNVs, specifically those relatively small in size, are more common in subjects with HLHS, but the frequency of large potentially disease-causing CNVs (>480,000 bp) did not differ between the HLHS and control populations.     

Confirmation of chromosomal microarray as a first-tier clinical diagnostic test for individuals with developmental delay,intellectual disability,autism spectrum disorders and dysmorphic features

Background and objectivesSubmicroscopic chromosomal rearrangements are the most common identifiable causes of intellectual disability and autism spectrum disorders associated with dysmorphic features. Chromosomal microarray (CMA) can detect copy number variants <1 Mb and identifies size and presence of known genes. The aim of this study was to demonstrate the usefulness of CMA, as a first-tier tool in detecting the etiology of unexplained intellectual disability/autism spectrum disorders (ID/ASDs) associated with dysmorphic features in a large cohort of pediatric patients.Patients and methodsWe studied 349 individuals; 223 males, 126 females, aged 5 months-19 years. Blood samples were analyzed with CMA at a resolution ranging from 1 Mb to 40 Kb. The imbalance was confirmed by FISH or qPCR. We considered copy number variants (CNVs) causative if the variant was responsible for a known syndrome, encompassed gene/s of known function, occurred de novo or, if inherited, the parent was variably affected, and/or the involved gene/s had been reported in association with ID/ASDs in dedicated databases.Results91 CNVs were detected in 77 (22.06%) patients: 5 (6.49%) of those presenting with borderline cognitive impairment, 54 (70.13%) with a variable degree of DD/ID, and 18/77 (23.38%) with ID of variable degree and ASDs. 16/77 (20.8%) patients had two different rearrangements. Deletions exceeded duplications (58 versus 33); 45.05% (41/91) of the detected CNVs were de novo, 45.05% (41/91) inherited, and 9.9% (9/91) unknown. The CNVs caused the phenotype in 57/77 (74%) patients; 12/57 (21.05%) had ASDs/ID, and 45/57 (78.95%) had DD/ID.ConclusionsOur study provides further evidence of the high diagnostic yield of CMA for genetic testing in children with unexplained ID/ASDs who had dysmorphic features. We confirm the value of CMA as the first-tier tool in the assessment of those conditions in the pediatric setting.     

基因拷贝数变异与先天性心脏病的研究进展

基因拷贝数变异是指与参考基因组相比,长度在1 kb以上的DNA片段缺失、插入、重复和复杂多位点的变异.基因拷贝数变异存在于人类和其他哺乳动物基因组中,与包括先天性心脏病在内的一系列复杂遗传性疾病相关.基因拷贝数变异是目前的研究热点之一.该文就基因拷贝数变异的概念、检测方法、在先天性心脏病领域进展作一综述.     

微阵列比较基因组杂交技术检测不明原因智力低下/发育迟缓患儿的基因组拷贝数变异

目的应用高分辨微阵列比较基因组杂交技术(Array-CGH),对中国人群不明原因的智力低下/发育迟缓(MR/DD)患儿进行全基因组拷贝数变异(CNVs)筛查,获得在这些不明原因MR/DD患儿中CNVs的检出率,并分析其中的罕见CNVs与MR/DD的相关性,以此评估Array-CGH对不明原因MR/DD可能的遗传病因诊断作用。方法根据特定筛选条件收集在首都儿科研究所临床诊断为不明原因MR/DD患儿,用Oligo244KDNA芯片筛查全基因组CNVs。针对所发现的CNVs,首先将其与国际基因组CNVs多态性数据库(databaseofgenomicvariants)进行比对,剔除常见多态性CNVs,将获得的罕见CNVs应用美国波士顿儿童医院遗传诊断实验室的临床分子诊断平台,结合基因组异常拷贝数数据库(DECIPHER)进行核查并与既往相关文献比对,以发现罕见CNVs在不明原因MR/DD患儿中的检出率。结果2004年7月至2008年7月共收集111例不明原因MR/DD患儿,平均年龄为6岁,男女比例为1.775。28例患儿发现36个罕见CNVs,CNVs平均长度为1326kb(29～8760kb),这些CNVs均无法被常规染色体G带检查所识别。通过评估,19例患儿携带可能与MR/DD相关的CNVs,另1例患儿的CNVs临床意义不明确,Array-CGH在不明原因MR/DD患儿中发现携带与疾病相关的罕见CNVs的诊断率为17.1%(19/111例)。22/36个(66.1%)罕见CNVs曾被美国波士顿儿童医院Array-CGH数据库、DECIPHER数据库、既往MR/DD微阵列研究文献所报道。1例患儿在15q11.2-13.1存在2098kb的基因组缺失,覆盖Prader-Willi综合征/Angelman综合征关键区的多个候选基因,包括SNRPN、NECDIN、SnRNAs和UBE3A,结合该患儿面部表型、临床检查以及Array-CGH结果,诊断为非典型性Prader-Willi综合征。结论基因组CNVs相关的微缺失/重复是中国人群中不明原因MR/DD患儿的原因之一,高分辨Array-CGH技术可在不明原因MR/DD患儿中发现更多的遗传病因,帮助和提高不明原因MR/DD的分子诊断水平。     

5p部分单体3例全基因组拷贝数变异分析

目的 应用全基因组微阵列芯片平台,对染色体核型提示为Cri du chat综合征的新生儿进行全基因组拷贝数变异（CNVs）的检测,以帮助解释基因型与表型的相关性。方法 2009年6月至2010年5月复旦大学附属儿科医院收治的染色体核型提示为Cri du chat综合征的3例新生儿进入研究。采用Cytogenetic Whole Genome芯片筛查全基因组CNVs,针对发现的所有CNVs进行分析,参照国际基因组拷贝数变异多态性数据库除外正常人群多态性CNVs。结合本研究3例与DECIPHER数据库已报道的Cri du chat综合征患儿的临床表型,行5p缺失大小及范围分析,对重复区域行候选基因分析。结果 3例患儿经微阵列芯片检测,均证实并更为精确的定位了5p的缺失范围。例1 5p缺失位于5p15.33-p13.3,例2 缺失位于5p15.33-5p15.1,例3 缺失位于5p15.33-p14.3;此外例2发现9p部分重复,例3发现7p部分重复。结合DECIPHER数据库已报道的5例Cri du chat综合征临床表型,重复区域和候选基因分析显示,临床表型为猫叫样哭声或声音异常：缺失片段重叠区域为5p15.33-15.31内3.86 Mb,覆盖(IRX1和IRX2与胚胎形成相关的基因);临床表型为面容异常：缺失片段重叠区域为5p15.2-15.1内2.51 Mb（覆盖ANKH与颅骨干骺端发育相关的基因）。例3合并有先天性巨结肠。因纳入病例均为新生儿,无法评价是否存在智力低下和生长发育迟缓,无法对相应的关键区域进行分析。结论 本研究提供了微阵列平台罕见潜在致病可能CNVs的分析方法,进一步为建立5p部分缺失表型基因型关联性提供了依据。     

微阵列比较基因组杂交技术对不明原因智力低下/生长发育迟缓患儿的分子诊断

目的　分析不明原因智力低下(ID)和(或)生长发育迟缓(DD)患儿潜在的致病性基因组不平衡, 及其与表型的相关性, 探讨高密度微阵列比较基因组杂交技术(array-CGH)在临床分子遗传学诊断中的应用价值。方法　采用array-CGH技术对16例ID/DD患儿进行全基因组扫描分析, 并用多重连接探针扩增技术(MLPA)对检出的基因组不平衡异位进行验证。结果　16例患儿高分辨G显带核型分析均无异常。6例(38%)患儿存在基因拷贝数异常(CNVs), 其中3例CNVs为正常多态性改变; 1例CNVs涉及4p16.3区域微缺失, 考虑为Wolf-Hirschhorn综合征; 1例CNVs涉及7q11.23区域微缺失, 考虑为Williams-Beuren 综合征; 另1例CNVs临床意义不明确, 包含2个重复突变, 该突变与智力低下、脑发育迟缓、特殊面容、隐睾、牙列不齐等有关, 证实该CNVs具有临床意义。结论 通过array-CGH技术对不明原因ID/DD患儿进行全基因组扫描, 可为部分患儿明确病因诊断。该技术作为一种高通量、快速的疾病研究手段, 在ID/DD的病因诊断中具有重要的临床意义。     

Genomic microarrays in clinical diagnosis

PURPOSE OF REVIEW: Cytogenetic analysis has for a long time relied on chromosome banding by karyotyping for whole-genome analysis of structural and numerical chromosomal anomalies. Conceptual and technical developments in molecular cytogenetics are rapidly changing the way the human genome is being analyzed by enhancing the resolving power from the megabase to the kilobase level. This review describes the various genomic microarray approaches that have been developed for molecular cytogenetic purposes and their implementation in a routine clinical diagnostic setting. RECENT FINDINGS: Genomic microarray approaches such as array-based comparative genomic hybridization have recently been shown to identify causative submicroscopic copy number alterations in a significant proportion of patients with mental retardation. These alterations occur throughout the human genome and the majority of these alterations reported thus far are unique. Next to these causative alterations, a large number of inherited submicroscopic copy number variations without immediate clinical consequences have been detected by these methods. SUMMARY: Genome profiling by genomic microarrays is becoming an important diagnostic tool, either in addition to or replacing conventional chromosome banding, depending on the expected diagnostic yield and the costs involved.     

Comparative genomic hybridization analysis of newly established retinoblastoma cell lines of adherent growth compared with Y79 of nonadherent growth

Retinoblastoma (RB) shows cytogenetic aberrations involving genes other than RB gene located on 13q14. We analyzed genomic aberration in newly established RB cell lines SNUOT-RB1 and SNUOT-RB4 of adherent growth and Y79 cell line of nonadherent growth by microarray comparative genomic hybridization. SNUOT-RB1 showed 44 significant copy number changes (gain in 11 and loss in 33, P<0.0005). SNUOT-RB4 showed 42 significant copy number changes (gain in 8 and loss in 34, P<0.0005). Y79 cell line had the greatest gain of 19.65-fold in the locus of MYCN gene 2p24.1, whereas SNUOT-RB1 and SNUOT-RB4 showed no significant gain. SNUOT-RB1 and SNUOT-RB4 gained chromosomal copy numbers commonly in chromosome 11, especially in locus 11q13, which is responsible for cancer-related genes such as CCND1, MEN1, and FGF3. Losses of copy numbers occurred in chromosomes 3, 9, 10, 11, 16, and 17. In summary, SNUOT-RB1 and SNUOT-RB4 represented similar pattern in gain and loss of chromosomal copy number changes, while different from Y79. The loss of CYLD gene of tumor suppressor gene, 16q12-q13, was only on locus of common involvement in 3 cell lines.     

11q24-q25缺失2例临床表型及文献复习

目的 应用全基因组微阵列芯片平台,对临床发现的多发性畸形患儿进行全基因组拷贝数变异（CNVs）的检测,并寻找基因型与临床表型的关系。方法 采用cytogenetic whole genome芯片筛查全基因组CNVs,针对发现的CNVs进行分析,参照国际基因组CNVs多态性数据库除外正常人群多态性CNVs。结合本研究2例与已报道的Jacobsen综合征(JBS)患儿的临床表型进行比较。结果 2例患儿SNP芯片分析为11q24-q25缺失（7.5和5.6 Mb）,均为末端的非单纯性缺失,例1存在12号染色体短臂的较大片段重复（11.5 Mb）,例2存在 11号染色体短臂的大片段重复（32.5 Mb）。2例共同缺失的部分均为JBS的关键区段,但临床表型与已报道的JBS患儿有所区别。2例均表现为头面部畸形、心血管系统异常和头颅影像学异常,均未发现血液系统异常。例1还表现为隐睾,例2表现为脾肿大。结论 对临床上难以诊断的多发性畸形可采用全基因组CNVs检测,以帮助明确诊断,对于丰富这一区段临床表型信息具有重要意义,尤其针对罕见疾病,更多的相似报道的后续出现,才能使建立表型-基因型关联性成为可能。     

MECP2 triplication in 3 brothers – A rarely described cause of familial neurological regression in boys

Male patients with large duplications of the methyl CpG-binding protein 2 (MECP2) gene have been identified with a characteristic phenotype consisting of infantile hypotonia replaced by spasticity, developmental delay, severe mental retardation and recurrent respiratory infections. Only one patient with MECP2 triplication, with a more severe phenotype has been reported so far. We report three brothers of unrelated parents with MECP2 triplication. Their phenotypic features include macrocephaly with large ears, infantile hypotonia, developmental delay, significant constipation, recurrent severe respiratory tract infections from early childhood, and seizures followed by neurological regression in late childhood. Our cases indicate that MECP2 triplication is similar to or more severe than that of MECP2 duplication syndrome.     

基于高通量测序技术的拷贝数变异筛选分析流程的建立及应用

目的 基于高通量测序的CNVs分析流程（PICNIC）与常规拷贝数变异微阵列比较基因组杂交检测方法的检测效率和结果分析。方法 纳入2016年1月1日至2017年12月31日复旦大学附属儿科医院分子诊断中心基于临床需要的、取得患儿家长知情同意的、同时送检了微阵列比较基因组杂交检测和高通量测序分析的病例。以微阵列比较基因组杂交为金标准，PICNIC为待测标准，微阵列比较基因组杂交检测采用安捷伦人类基因组CGH微阵列180K试剂盒，并经其软件进行数据处理和拷贝数变异检测。选择重复片段>500kb，缺失片段>200 kb 的CNVs 数据分析，经过筛选后，结合患儿表型人工进行结构评判，致病/可能致病（P/LP）为检测到的CNVs已知的表型与患儿表型相符合；临床意义未明（VUS）为检测到的CNVs已知的表型与患儿表型不完全相符合。PICNIC分析流程，从同一测序批次的BAM文件开始，经过外显子覆盖深度计算、质控筛选、CANOES计算CNVs评分并提供候选CNVs。后续从基因水平和区域水平二方面对CNVs进行注释和筛选。比较2种方法间检出率及其敏感性。结果 113例同时送检了微阵列比较基因组杂交检测和PICNIC测序分析流程，平均年龄2岁，发育迟缓82例，惊厥16例，孤独症5例，先天性心脏病3例，遗传咨询病例7例。微阵列比较基因组杂交检测到P/LP为76例，VUS为16例；PICNIC检测到P/LP为92例，VUS为21例；微阵列比较基因组杂交检测到的P/LP和VUS病例，均包含在PICNIC检测到的病例中，16例微阵列比较基因组杂交检测VUS结论的CNVs被PICNIC纳入P/LP，敏感度100%（95%CI: 94 %~100%），特异度100%（95%CI: 81%~100%），阳性预测值82.6%（95%CI: 73%~89），阴性预测值56.8%（95%CI: 40%~72%）。微阵列比较基因组杂交检测到的446个CNVs中，PICNIC也检测到190个，在PICNIC到的236个CNVs中，微阵列比较基因组杂交检测也检测到190个。结论 PICNIC分析流程对于P/LP的CNVs，具有100%的特异性和敏感性，可用于CNVs的临床检测。该方法的建立及临床推广对于进一步挖掘高通量捕获测序数据具有重要意义。     

MECP2基因甲基化和羟甲基化水平的性别差异研究

目的 探讨MECP2在不同性别脑组织中是否有表达差异,从而与孤独症等疾病的性别差异相关。方法 利用4例非疾病流产胎儿脑标本,采用酚氯仿方法提取基因组DNA。在MethPrimer在线软件上检测MECP2基因-1 000 bp至+1 200 bp区间的CpG 岛。甲基化检测采用亚硫酸氢盐修饰后测序法（使用EZ DNA Methylation-goldTM Kit 试剂盒）。对于超声断裂后的基因组DNA,用基因组羟甲基化试剂盒（diagenode,hMeDIP kit）进行ChIP反应。反转录cDNA采用FastQuant RT Kit（With gDNase）试剂盒,定量PCR检测MECP2表达量采用 SuperReal PreMix Plus （SYBR Green）试剂盒。结果 标本1男,重量106 g,长度17.4 cm;标本2女,重量100 g,长度19.1 cm;标本3男,重量500 g,长度28.3 cm;标本4女,重量510 g,长度31.5 cm。MECP2表达量男性胚胎（标本1=0.0367,标本3=0.0155）高于女性胚胎（标本2=0.0177,标本4=0.0088）。MECP2的甲基化水平女性个体平均1条X染色体上MECP2的甲基化程度显著高于男性,特别是在启动子的核心区域-309 bp至-179 bp,男性MECP2上几乎没有甲基化,而羟甲基化水平男性高于女性。结论 男性MECP2基因的DNA修饰促进其表达,可能提高了男性胚胎对MECP2基因突变的易感性,从而影响MECP2基因突变导致的患病人群的性别差异。     

Coffin-Siris syndrome with bilateral macular dysplasia caused by a novel exonic deletion in ARID1B

Coffin-Siris syndrome (CSS) is a congenital anomaly syndrome characterized by developmental delay, coarse facial features, and hypoplasia of the fifth digit's nail or phalanges. Herein, we report a case of the 8-year-old female patient who showed developmental delay associated with dysplasia in the macular and large toe area. Comprehensive genomic analysis showed no possible candidate variants, but the subsequent genomic copy number analysis revealed a novel exonic deletion in the coding region of AT-rich interactive domain-containing protein 1B (ARID1B), a gene responsible for CSS. Genomic copy number analysis can aid in diagnosing CSS by confirming undiagnosed exonic deletions in ARID1B. Furthermore, this is the first report of CSS associated with bilateral macular dysplasia.     

Pelizaeus–Merzbacher disease as a chromosomal disorder

Pelizaeus–Merzbacher disease (PMD) is a congenital hypomyelination disorder caused by alterations affecting the proteolipid protein 1 gene (PLP1) located on Xq22.2. Generally, patients with PLP1 missense mutations show the most severe form of PMD (connatal form); however, two‐thirds of patients with PMD carry PLP1 duplications and present typical manifestations of the disorder, recognized as the classical form. Other rare PLP1 abnormalities have been also identified, including X‐chromosome translocations, triplications, and a partial duplication, all involving PLP1. The genomic structure of the distal end of the PLP1 locus, characterized by repeated genomic segments, contributes to the chromosomal rearrangements around PLP1 and the manifestation of PMD. Thus, PMD is recognized as a chromosomal disorder.     

Phenotype profiling of patients with intellectual disability and copy number variations

BackgroundNowadays the microarray technology allows whole-genome analysis with a high resolution and performance for the genetic diagnosis in any patient with intellectual disability or autism spectrum disorder. However in the immediate future, with the development of massive sequencing systems for application at clinical diagnosis, it will be necessary to have clinical criteria to guide studies.AimTo perform an exhaustive clinical definition of patients with pathogenic copy number variations in order to establish the clinical criteria most suggestive of this kind of genomic rearrangements.MethodWe designed and implemented a database to collect 190 different clinical variables (pregnancy, neonatal, facial dysmorphism, congenital anomalies, neurological features and family history) in a series of 246 patients, with developmental delay/intellectual disability. All cases were studied with array comparative genomic hybridization.ResultsWe have found a pathogenic genomic imbalance in 73 patients. Frequency analysis of all clinical variables showed that growth disorder, abnormalities of hands, low-set ears and hypertelorism are the more frequent features among patients with genomic rearrangements. However other clinical features, such as genital abnormalities and aggressiveness, are more specifically associated with pathogenic copy number variations in spite of their low frequencies in the overall series, yielding higher statistical significance values than other traits.ConclusionsThe genotype–phenotype comparison may be useful to set in the future the main clinical manifestations associated with deletions, duplications and unbalanced translocations. Theses analyses will improve the clinical indications and protocols to implement genomic arrays in the genetic study of patients with neurodevelopment disorders.     

Technique d’hybridation génomique comparative sur microréseau d’ADN et fœtopathologie

Microarray-based comparative genomic hybridization (aCGH) is becoming an efficient clinical diagnostic tool enabling genome-wide screening of segmental copy number variations (CNVs). Regarding its ability to detect segmental genomic CNVs in individuals with mental retardation, autism and multiple congenital anomalies, aCGH is gradually replacing cytogenetic methods. Using this tool as a prenatal test for foetal genomic imbalance offers the promise of detecting pathogenic gain or loss of genomic material more quickly and much more frequently than current methods. However, there is a concern about CNVs of uncertain significance (for example, predisposition to adult occurring disease with incomplete penetrance) which might lead to termination of normal pregnancies. We report in this article recent data using aCGH in foetuses from spontaneous or medically terminated pregnancies associated with multiple malformations. aCGH should be considered as a diagnostic tool to improve genetic counselling in fetopathology. We also report recent data on aCGH as a prenatal test. Larger studies with targeted arrays are mandatory to determine whether the improved overall detection rates of clinically chromosomal abnormalities will justify offering aCGH in a prenatal diagnosis setting.     

50例微缺失和微重复综合征患儿的临床表型及基因组拷贝数变异的分析

目的了解微缺失和微重复综合征(MMSs)的基因型与临床表型的关系及致病性拷贝数变异(CNVs)的发生机制。方法收集2013年6月至2015年9月,应用染色体微阵列(CMA)诊断为MMSs的患儿50例,总结分析其临床表现和致病性CNVs的特点。结果 50例MMSs患儿临床表现以精神发育迟滞(MR)、发育迟缓(DD)、矮小、特殊面容为主,且往往多系统的异常同时存在,共存在54处致病性CNVs,微缺失片段36个、微重复片段18个,片段大小介于28kb至48.5Mb,平均13.86Mb。致病性CNVs易发生在X染色体、15号染色体、1号染色体。结论 MMSs临床表现缺乏特异性,可以采取基因型优先的方法进行诊断。遗传方式、重组类型(缺失或者重复)、片段大小以及所包含的功能基因有利于新生突变CNVs的解读,少见发病机制的深入研究有望成为发现新的罕见MMSs的突破点。     

MLPA技术检测儿童ETV6/RUNX1~+急性淋巴细胞白血病基因拷贝数的变异

目的应用多重连接探针扩增技术(MLPA)检测在ETV6/RUNX1~+急性淋巴细胞白血病(ALL)患儿中基因拷贝数变异的情况,并与常规经典染色体核型分析及荧光原位杂交技术(FISH)检测进行比较,以评估MLPA技术的应用价值。方法回顾性分析2006年1月至2012年11月95例ETV6/RUNX1+ALL患儿的临床资料,包括临床特征、染色体核型检测结果及FISH检测结果。应用MLPA技术检测95例患儿中多个基因拷贝数变异的情况。结果 95例患儿中,73例(77%)检测到基因拷贝数的改变。每例患儿基因拷贝数变异个数的中位数为1(0~6)个。拷贝数变异率超过10%的基因为EBF1、CDKN2A/2B、PAX5、ETV6、RB1、BTG1。以上经MLPA技术检测到拷贝数变异的基因涉及的染色体片段在染色体核型检测中常检测不到改变。FISH技术检测ETV6基因拷贝数的结果与MLPA检测结果的符合率为66%。结论 MLPA可作为高效、简便的方法检测ETV6/RUNX1~+ALL患儿基因拷贝数的变异。     

CNV-seq技术检测90例发育迟缓患儿基因组拷贝数变异的遗传学分析

目的 探讨发育障碍疾病患儿致病性拷贝数变异(CNV)的特征.方法 收集2017至2019年诊断为发育迟缓、并经核型分析患儿的临床资料,采集患儿外周血进行基于高通量测序的低深度全基因组测序(CNV-seq).利用ClinVar、DECIPHER、OMIM、DGV数据库注释CNV数据,依据ACMG评估CNV致病性,并通过P...     

Confirmation of genetic homogeneity of syndactyly type IV and triphalangeal thumb–polysyndactyly syndrome in a Chinese family and review of the literature

Syndactyly type IV (SD4) is inherited in an autosomal dominant fashion and characterized by complete cutaneous syndactyly of all fingers accompanied with polydactyly. Triphalangeal thumb–polysyndactyly syndrome (TPTPS) consists of a triphalangeal thumb, polydactyly, and syndactyly and is transmitted in an autosomal dominant manner with variable expression. Genomic duplications of the long-range limb-specific cis-regulator (ZRS) cause SD4 and TPTPS. Here, we report two individuals from a Chinese family with syndactyly. One individual had overlapping clinical symptoms of TPTPS and SD4, while the other had a typical SD4 with postaxial polydactyly of the toe. Results of quantitative PCR suggested that the duplication of ZRS involved all affected individuals, and array comparative genomic hybridization detected its size as 115.3 kb. Conclusion: This work confirms the genetic homogeneity of SD4 and TPTPS. Our result expands the spectrum of ZRS duplications. TPTPS and SD4 should be considered as a continuum of phenotypes.