This article reports on the clinical and genetic characteristics of monozygotic twins with Marshall-Smith syndrome (MRSHSS) due to a mutation in the NFIX gene, along with a review of related literature. Both patients presented with global developmental delays, a prominent forehead, shallow eye sockets, and pectus excavatum. Genetic testing revealed a heterozygous splicing site mutation c.697+1G>A in both children, with parents showing wild-type at this locus. According to the guidelines of the American College of Medical Genetics and Genomics, this mutation is considered likely pathogenic and has not been previously reported in the literature. A review of the literature identified 32 MRSHSS patients with splicing/frameshift mutations. Accelerated bone maturation and moderate to severe global developmental delay/intellectual disability are the primary clinical manifestations of patients with MRSHSS. Genetic testing results are crucial for the diagnosis of this condition.
该文报道了一对NFIX基因变异导致Marshall-Smith综合征（Marshall-Smith syndrome, MRSHSS）的同卵双胞胎临床及遗传学特点并对相关文献进行复习。2例患儿均表现为全面发育落后、高额头、浅眼眶、漏斗胸。基因检测提示2例患儿均存在NFIX杂合剪接位点变异c.697+1G>A，父母该位点为野生型，根据美国医学遗传学与基因组学学会指南判定为可能致病性变异，该位点突变既往未见文献报道。复习文献共发现32例MRSHSS患者，突变类型为剪切/移码突变。骨骼成熟加速、中至重度全面发育迟缓/智力障碍是MRSHSS患者最主要的临床表现。基因检测结果是该病重要的诊断依据。.
Keywords: Abnormal bone maturation; Child; Global developmental delay/intellectual disability; Marshall-Smith syndrome; NFIX gene.