Clinical and genetic analysis of a child with hyperekplexia / 中华神经科杂志

ABSTRACT

Objective:To analyze the clinical phenotype and gene sequencing results of a child with hyperekplexia, and to clarify her genetic etiology.Methods:The clinical information of the child was collected, and the whole exome sequencing of the child and her parents was performed. The suspected pathogenic variants were verified by Sanger sequencing and bioinformatics analysis.Results:There was a 12 years old girl, who was hospitalized in the Department of Pediatric Neurology of Linyi People′s Hospital because of "paroxysmal limb stiffness for more than 11 years and aggravated for half a month" on July 4, 2022. The girl showed exaggerated startle reflexes and generalized siffness in response to external sudden, unexpected stimuli, occasionally accompanied by apnea and cyanosis, frequent attacks occurred several times a day, lasting for 1-30 minutes, and early head and abdomen flexion can be relieved. She showed normal growth and development, no abnormality in brain magnetic resonance imaging and video electroencephalogram during seizure. The whole exome sequencing showed that there was a missense heterozygous mutation c.643T>C(p.W215R) in the SLC6A5 gene of the child. Neither of the parents carried this mutation, which was a novel and de novo variant. According to the guidelines of American College of Medical Genetics and Genomics, this variant was a likely pathogenic variant [PS2: de novo (both maternity and paternity confirmed) in the patient with the disease and no family history; PM2: undetected variants in the normal population; PP3: multiple softwares predicted that this mutation would have harmful effects on genes or gene products], and highly conserved. Swiss modeling found that the hydrogen bond of the modified amino acid also changed. Conclusions:Hyperekplexia is relatively rare and prone to misdiagnosis. The main clinical features are excessive startle reflexes (limb shaking, or jumping) to unexpected external stimuli, resulting in overall stiffness, normal growth and development, and normal video electroencephalogram during the seizure. The likely pathogenic heterozygous missense variant c.643T>C (p.W215R) of SLC6A5 gene is the genetic cause of this case.