Large De Novo Microdeletion in Epilepsy with Intellectual and Developmental Disabilities, with a Systems Biology Analysis.

Epilepsy is one of the most common complex neurological diseases. It is frequently associated with intellectual and developmental disabilities (ID/DD). In recent years, copy number variation (CNV), especially microdeletion, was proven to be a potential key factor of genetic epilepsy. In this paper, the authors tested the hypothesis that the large de novo rare CNV is an important cause of epilepsy with ID/DD. We performed a custom array comparative genomic hybridization (aCGH) to detect the CNVs of 96 Chinese epileptic patients with ID/DD. The aCGH was designed with a higher density probe coverage of 320 genes known to be involved in epilepsy and ID/DD with lower density whole-genome backbone coverage. We detected 9 large de novo rare microdeletions from 8 patients. These CNVs are located on 2q24.1, 2q33.1-q34, 5q13.2 (2 similar CNVs), 5q33.1-q34, 17p13.2, 22q11.21-q11.22 (2 identical CNVs) and Xp22.31. We also found that only a few genes in the CNVs are known epilepsy related genes. By analysis with systems biology, we found most of the genes are interacting genes known to be epilepsy related genes. We also found a gene motif "BGNADP", constructed by BTD, GALNT10, NMUR2, AUTS2, DLG2 and PTPRD, would be a key motif in epilepsy and ID/DD. These findings strongly indicate that some large de novo rare microdeletion is an important pathological cause of epilepsy with ID/DD. Our study also found a gene motif "BGNADP" should be a key small network in epilepsy with ID/DD.