Identification of a Novel homozygous Splice-Site Deletion in KCTD7 Gene Associated with Progressive Myoclonic Epilepsy

Abstract

Objective: To study the Progressive myoclonic epilepsies (PME) that is genetic disorders resulting from mutations in different genes, all characterized by the early onset of myoclonic seizures, and cognitive decline. The Potassium Channel Tetramerization Domain Containing seven (KCTD7) gene encodes for the BRC (broad complex), ttk (tramtrack), and bab/pox virus, and zinc finger domain, containing KCTD7 protein.

Methodology: The study was done in the Center of Excellence in Genomic Medicine and Research (CEGMR). The affected patient, a three-year-old Saudi female born to consanguineous parents, she underwent laboratory tests, EEG assessments, and Whole-Exome Sequencing (WES).

Results: Our results showed a novel five base pair deletion that was detected in homozygous state in the KCTD7 gene. Both the unaffected parents showed heterozygous mutation of the KCTD7 gene. Segregation analysis via Sanger sequencing supported the existence of the homozygous splice donor variant in NM_153033.4:c.493+2_493+6delTGA of KCTD7 gene in the patient.

Conclusion: The mutation is not reported in the literature yet; the particular phenotype that was observed in our patient is comparable to the ones that are described in the KCTD7 related pathologies, combined with segregation analysis indicating both parents carried the variant heterogeneously present is a strong indication that the identified mutation consists of probably pathogenic mutation. This finding will further increase our insight of the genetic basis of PMEs and role of KCTD7 gene mutations in Saudi population.