DCX variants in two unrelated Chinese families with subcortical band heterotopia: Two case reports and review of literature

Introduction: Subcortical band heterotopia (SBH) is a rare brain developmental malformation caused by deficient neuronal migration during embryogenesis. Published literature on pediatric SBH cases caused by DCX mutations is limited.Methods: The detailed clinical and genetic features of two pediatric SBH with DCX mutations were analyzed. The available literature on DCX mutations was reviewed.Results: Both patients were girls with varying degrees of developmental delay. Patient 1 was short in stature with peculiar facial features. Patient 2 had an early seizure onset and developed drug-resistant epilepsy. Whole-exome sequencing (WES) revealed two de novo heterozygous variants of DCX (NM_178153.3), including a novel missense variant of c.568A > G (p.K190E) in P1 and a reported nonsense variant of c.814C > T (p.R272*) in P2. We reviewed all the available literature regarding DCX mutations. A total of 153 different mutations have been reported, with the majority of 99 (64.7 %) being missense mutations.Conclusion: Our study expanded the mutational spectrum of DCX, which has important implications for the study of genotype-phenotype correlations. Furthermore, it provided insights to better understand SBH and genetic counseling.