Paternal transmission of subcortical band heterotopia through DCX somatic mosaicism

Subcortical band heterotopia (SBH), also known as ‘double cortex’ syndrome, is characterized by a band of heterotopic neurons interspersed in the white matter between the cortex and the lateral ventricles and is usually a severe disease with patients showing variable degrees of developmental delay, intellectual disability, motor impairment and epilepsy [1]. This is a true neuronal migration disorder that in the majority of the cases is due to defects in the doublecortin gene (DCX) [1]. As DCX is located on the X-chromosome, patients usually show a de novo mutation or inherit the mutated allele from the mother. Here we describe a woman with epilepsy due to SBH that inherited a DCX mutation from her father.