患者，男，4岁2个月，因语言、运动发育落后1年余就诊，并有步态不稳、眼神交流差、刻板行为及癫癎发作。查体发现面容特殊：斜头畸形、眼睑下垂、鼻梁扁平、两侧嘴角下沉、耳位较低等，以及左手小手指2节。辅助检查提示脊柱侧弯、室间隔缺损、语言发育迟缓和中度智力障碍，染色体核型无异常，全基因组SNP芯片技术检测发现患者12号染色体q24.21区域重复1个拷贝、大小为1.03 Mb，患者父母该区域未见异常。确诊为MED13L综合征。MED13L基因点突变、缺失或重复突变均可导致MED13L综合征，不同的基因型可导致不同的临床表型。SNP技术可协助确诊。

A boy aged 4 years and 2 months was found to have delayed language and motor development, instability of gait, poor eye contact, stereotyped behavior, and seizure at the age of 3 years. Physical examination showed special facial features, including plagiocephaly, blepharoptosis, wide nasal bridge, down-turned mouth corners at both sides, and low-set ears. There were only two knuckles at the little finger of the left hand. The anteroposterior and lateral films of the spine showed scoliosis; echocardiography showed ventricular septal defect; the Gesell Developmental Scale showed delayed language development and moderate intellectual disability; there were no abnormalities in the karyotype; genome-wide SNP arrays found a duplication in 12q24.21 region with a size of 1.03 Mb in chromosome 12, while this was not seen in his parents. The boy was diagnosed with MED13L syndrome. Point mutation, deletion, and duplication in the MED13L gene can lead to MED13L syndrome. The patients with different genotypes may have different phenotypes. Genome-wide SNP arrays may help with the diagnosis of this disease.