Williams syndrome (WS) is a relatively rare microdeletion disorder that occurs in as many as 1:7,500 individuals. WS arises due to the mispairing of low-copy DNA repetitive elements at meiosis. The deletion size is similar across most individuals with WS and leads to the loss of one copy of 25–27 genes on chromosome 7q11.23. The resulting unique disorder affects multiple systems, with cardinal features including but not limited to cardiovascular disease (characteristically stenosis of the great arteries and most notably supravalvar aortic stenosis), a distinctive craniofacial appearance, and a specific cognitive and behavioural profile that includes intellectual disability and hypersociability. Genotype–phenotype evidence is strongest for ELN, the gene encoding elastin, which is responsible for the vascular and connective tissue features of WS, and for the transcription factor genes GTF2I and GTF2IRD1, which are known to affect intellectual ability, social functioning and anxiety. Mounting evidence also ascribes phenotypic consequences to the deletion of BAZ1B, LIMK1, STX1A and MLXIPL, but more work is needed to understand the mechanism by which these deletions contribute to clinical outcomes. The age of diagnosis has fallen in regions of the world where technological advances, such as chromosomal microarray, enable clinicians to make the diagnosis of WS without formally suspecting it, allowing earlier intervention by medical and developmental specialists. Phenotypic variability is considerable for all cardinal features of WS but the specific sources of this variability remain unknown. Further investigation to identify the factors responsible for these differences may lead to mechanism-based rather than symptom-based therapies and should therefore be a high research priority.

威廉姆斯综合征 (WS) 是一种相对罕见的微缺失疾病，发生率高达 1:7,500。WS 的产生是由于减数分裂时低拷贝 DNA 重复元件的错配。大多数 WS 个体的缺失大小相似，导致染色体 7q11.23 上 25-27 个基因的一个拷贝丢失。由此产生的独特疾病影响多个系统，其主要特征包括但不限于心血管疾病（特征性大动脉狭窄，最明显的是瓣上主动脉瓣狭窄）、独特的颅面外观以及特定的认知和行为特征，包括智力障碍和超社交性。ELN的基因型-表型证据最强，编码弹性蛋白的基因，负责 WS 的血管和结缔组织特征，以及已知会影响智力、社交功能和焦虑的转录因子基因GTF2I和GTF2IRD1 。越来越多的证据也将表型后果归因于BAZ1B、LIMK1、STX1A和MLXIPL的缺失，但需要做更多的工作来了解这些缺失对临床结果的影响机制。世界上一些地区的诊断年龄已经下降，技术进步（例如染色体微阵列）使临床医生能够在没有正式怀疑的情况下对 WS 进行诊断，从而允许医学和发育专家进行早期干预。WS 的所有主要特征的表型变异性相当大，但这种变异性的具体来源仍然未知。进一步调查以确定导致这些差异的因素可能会导致基于机制而不是基于症状的治疗，因此应该是一个高度的研究重点。