Lissencephaly type 1 due to doublecortin gene mutation

Lissencephaly type 1 due to doublecortin (DCX) gene mutation, also known as X-linked lissencephaly or subcortical band heterotopia (SBH), is a rare brain malformation disorder caused by mutations in the DCX gene located on the X chromosome. The DCX gene encodes doublecortin, a protein essential for neuronal migration during embryonic brain development. When this gene is mutated, neurons fail to migrate properly to their correct positions in the cerebral cortex, resulting in a smooth brain surface (lissencephaly) or abnormal bands of misplaced neurons beneath the cortex (subcortical band heterotopia, also called "double cortex" syndrome). This condition predominantly affects the central nervous system. In hemizygous males, the presentation is typically more severe, with classical lissencephaly characterized by a smooth or nearly smooth brain surface, severe intellectual disability, intractable epilepsy (often infantile spasms), feeding difficulties, and significant motor impairment including spasticity. Affected males may also have microcephaly. In heterozygous females, the phenotype is generally milder due to random X-inactivation, often presenting as subcortical band heterotopia with variable degrees of intellectual disability and epilepsy. Some females may have normal intelligence with seizures as the primary manifestation. There is currently no cure or disease-modifying treatment for lissencephaly type 1 due to DCX mutations. Management is supportive and symptomatic, focusing primarily on seizure control with antiepileptic medications, physical and occupational therapy to optimize motor function, speech therapy, nutritional support (sometimes requiring gastrostomy tube placement), and management of respiratory complications. Genetic counseling is important for affected families given the X-linked inheritance pattern. Prognosis varies significantly between males and females, with severely affected males often having a shortened lifespan, while females with subcortical band heterotopia may have a more favorable outcome.

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