X-linked lissencephaly is associated with a hemizygous mutation in DCX gene located on the X-chromosome. DCX mutation causes classic lissencephaly in males and subcortical laminar heterotopia in females. Neuronal migration arrest leads to pachygyria and the arrested neurons are noted along the path of neuronal migration between the periventricular region and the cortex. Diffusion tensor imaging in cases of lissencephaly shows abnormal radial arrangement of fibers within the cortex in a "hairon-end" pattern. We demonstrate this "hair-on-end" pattern of fibers within the thickened cortex in a case of lissencephaly due to a pathogenic mutation in DCX gene confirmed on next generation whole exome sequencing.

Patients with lissencephaly typically present with severe psychomotor retardation and drug-resistant seizures. The aim of this study was to characterize the epileptic phenotype in a genotypically and radiologically well-defined patient cohort and to evaluate the response to antiseizure medication (ASM). Therefore, we retrospectively evaluated 47 patients of five genetic forms (LIS1/PAFAH1B1, DCX, DYNC1H1, TUBA1A, TUBG1) using family questionnaires, standardized neuropediatric assessments, and patients' medical reports. All but two patients were diagnosed with epilepsy. Median age at seizure onset was 6 months (range: 2.1-42.0), starting with epileptic spasms in 70%. Standard treatment protocols with hormonal therapy (ACTH or corticosteroids) and/or vigabatrin were the most effective approach for epileptic spasms, leading to seizure control in 47%. Seizures later in the disease course were most effectively treated with valproic acid and lamotrigine, followed by vigabatrin and phenobarbital, resulting in seizure freedom in 20%. Regarding psychomotor development, lissencephaly patients presenting without epileptic spasms were significantly more likely to reach various developmental milestones compared to patients with spasms. Classic lissencephaly is highly associated with drug-resistant epilepsy starting with epileptic spasms in most patients. The standard treatment protocols for infantile epileptic spasms syndrome lead to freedom from seizures in around half of the patients. Due to the association of epileptic spasms with an unfavorable course of psychomotor development, early and reliable diagnosis and treatment of spasms should be pursued. For epilepsies occurring later in childhood, ASM with valproic acid and lamotrigine, followed by vigabatrin and phenobarbital, appears to be most effective.

Noncentrosomal microtubules are essential cytoskeletal filaments that are important for neurite formation, axonal transport, and neuronal migration. They require stabilization by microtubule minus-end-targeting proteins including the CLASP family of molecules. To date, no human monogenic disorder has been associated with the CLASP1 gene. In this study, we aimed to delineate the clinical and neuroradiologic phenotype associated with biallelic CLASP1 variants. We analyzed clinical characteristics, MRI data, and genotypes of a cohort of 3 patients with homozygous variants in CLASP1. Homozygous CLASP1 variant is associated with primary microcephaly, severe neurodevelopmental delay, and early-onset refractory epilepsy. The neuroradiologic phenotype comprises a highly recognizable combination of classic lissencephaly, with the posterior gradient more severe than the anterior gradient, a thin/hypoplastic splenium of the corpus callosum, mild enlargement of the lateral ventricles primarily posteriorly with a squared pattern, and pontine hypoplasia. This study underscores the role of CLASP1 in brain development and suggests that the identified variant disrupts CLASP1 interaction with the microtubule cytoskeleton, contributing to lissencephaly pathogenesis.

This case report investigates the management of a 24-week-old neonate with congenital cytomegalovirus (CMV) infection and its sequelae, including severe intrauterine growth restriction, thrombocytopenia, and brain anomalies, ultimately progressing to lissencephaly. The diagnostic challenges included delayed clinical suspicion of congenital CMV, which was not identified until after delivery through CMV DNA polymerase chain reaction, and differentiating its symptoms from other potential causes of the neonate's condition. Aggressive interventions included antibiotics, antiviral therapy with ganciclovir, and supportive measures such as intubation, CPR, respiratory support, blood transfusions, and management of coagulopathy. Despite these efforts, the patient deteriorated due to progressive hypoperfusion, hypoxemic cardiorespiratory failure, and disseminated intravascular coagulopathy. Due to the poor prognosis and extent of multiorgan damage, support was withdrawn per parental consent. This case highlights the complications encountered when managing an advanced-stage neonatal CMV infection and emphasizes the importance of a multidisciplinary and holistic approach to guide diagnosis and treatment.

About 50% of individuals with developmental and epileptic encephalopathies (DEEs) are unsolved following genetic testing. Deep intronic variants, defined as >100 bp from exon-intron junctions, contribute to disease by affecting the splicing of mRNAs in clinically relevant genes. Identifying deep intronic pathogenic variants is challenging and resource intensive, and interpretation is difficult due to limited functional annotations. We aimed to identify deep intronic variants in individuals suspected to have unsolved single gene DEEs. In a research cohort of unsolved cases of DEEs, we searched for children with a DEE syndrome predominantly caused by variants in specific genes in >80% of described cases. We identified two children with Dravet syndrome and one individual with classic lissencephaly. Multiple sequencing and bioinformatics strategies were employed to interrogate intronic regions in SCN1A and PAFAH1B1. A novel de novo deep intronic 12 kb deletion in PAFAH1B1 was identified in the individual with lissencephaly. We showed experimentally that the deletion disrupts mRNA splicing, which results in partial intron retention after exon 2 and disruption of the highly conserved LisH motif. We demonstrate that targeted interrogation of deep intronic regions using multiple genomics technologies, coupled with functional analysis, can reveal hidden causes of unsolved monogenic DEE syndromes. PLAIN LANGUAGE SUMMARY: Deep intronic variants can cause disease by affecting the splicing of mRNAs in clinically relevant genes. A deep intronic deletion that caused abnormal splicing of the PAFAH1B1 gene was identified in a patient with classic lissencephaly. Our findings reinforce that targeted interrogation of deep intronic regions and functional analysis can reveal hidden causes of unsolved epilepsy syndromes.