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

Contactin 2, encoded by on chromosome 1q32.1, is a neural-specific glycoprotein and plays important roles in neurodevelopment. A deleterious homozygous variant in the 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 and epilepsy. Here, we reported one new case, who presented with epilepsy, carrying a novel homozygous frameshift variant in . The clinical and genetic features of the patient were reviewed. 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 (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 in the proband. This case enhanced the gene-disease relationship between and epilepsy, which will help to further understand this emerging disorder.