AUTHOR=Chen Wenjie , Chen Fei , Shen Yiping , Yang Zhixian , Qin Jiong 

TITLE=Case Report: A Case of Epileptic Disorder Associated With a Novel CNTN2 Frameshift Variant in Homozygosity due to Maternal Uniparental Disomy

JOURNAL=Frontiers in Genetics

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2021.743833

DOI=10.3389/fgene.2021.743833

ISSN=1664-8021

ABSTRACT=<p><bold>Background:</bold> Contactin 2, encoded by <italic>CNTN2</italic> on chromosome 1q32.1, is a neural-specific glycoprotein and plays important roles in neurodevelopment. A deleterious homozygous variant in the <italic>CNTN2</italic> gene was previously reported to cause autosomal recessive cortical myoclonic tremor and epilepsy. Since then, there has been no further report confirming the association of <italic>CNTN2</italic> and epilepsy. Here, we reported one new case, who presented with epilepsy, carrying a novel homozygous frameshift variant in <italic>CNTN2</italic>. The clinical and genetic features of the patient were reviewed.</p><p><bold>Case presentation:</bold> The male patient presented with preschool age-of-onset neurodevelopmental impairment and focal seizures of temporal origin, and responded to valproate. A trio-whole exome sequencing revealed a novel homozygous frameshift variant in <italic>CNTN2</italic> (c.2873_c.2874delCT, p.Thr958Thrfs). The patient’s mother was a heterozygous carrier while his father was wild-type; they were both unaffected and non-consanguineous. Further study revealed that maternal uniparental disomy (1q32.1) unmasked the heterozygous variant of <italic>CNTN2</italic> in the proband.</p><p><bold>Conclusions:</bold> This case enhanced the gene–disease relationship between <italic>CNTN2</italic> and epilepsy, which will help to further understand this emerging disorder.</p>