Knobloch Syndrome-1 is a rare autosomal recessive disorder typically diagnosed postnatally and characterized by occipital encephalocele, high myopia, and vitreoretinal degeneration. We describe a fetus with a constellation of prenatal neuroimaging findings, including occipital cephalocele, vermian dysplasia, bilateral polymicrogyria, and ocular elongation, that prompted genetic investigation. Trio exome sequencing identified biallelic pathogenic variants in COL18A1, confirming the diagnosis of Knobloch Syndrome-1. This case highlights how advanced fetal neuroimaging and prenatal exome sequencing can facilitate early recognition of syndromes like Knobloch, and underscores the importance of considering COL18A1-related disorders when multiple central nervous system anomalies are detected prenatally.

We studied three brothers and a maternal half-brother featuring global developmental delay, mild to moderate intellectual disability, epilepsy, microcephaly, and strabismus. All had bilateral perisylvian and perirolandic polymicrogyria, while some also had malformations of the hippocampus (malrotation and dysplasia), cerebellum (heterotopias and asymmetric aplasia), corpus callosum dysgenesis, and brainstem asymmetric dysplasia. Exome sequencing showed that all four patients had a novel variant (c.1597C>T:p.Leu533Phe) on the KIF4A gene on chromosome X. We discuss how this variant is possibly pathogenic and could explain the reported phenotype.

This report describes a pediatric case of megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndrome, a rare neurodevelopmental disorder caused by pathogenic variants in the AKT3, CCND2, or PIK3R2 genes. We present a patient with a rare CCND2 variant (c.839C>T, p.Thr280Ile), associated with infantile spasms, ventriculomegaly, polymicrogyria, and intraventricular hemorrhage (IVH). A retrospective chart review and literature search were performed using PubMed. Our patient was found to have ventriculomegaly, grade 3 IVH, bilateral polymicrogyria, and restricted diffusion in the caudate nuclei prenatally. No polydactyly was observed. The patient developed infantile spasms at age 5 months. While high-dose prednisone treatment failed to control the spasms, they resolved with topiramate. By age 2 years, the patient continued to have significant developmental delays, including having poor tone and being nonverbal. MPPH syndrome remains a rare and challenging diagnosis, with fewer than 100 cases reported. This case highlights the importance of early genetic testing and neuroimaging in the diagnosis and management of MPPH. The unique presentation of IVH and restricted diffusion warrants further investigation into the syndrome's variable phenotypic spectrum. Early intervention and targeted therapy may help manage seizure activity and improve outcomes.

Recessive LAMC3 mutations are recognized to cause epilepsy with cortical malformations characterized by polymicrogyria and pachygyria. The objective of this study was to describe the clinical picture and epilepsy phenotype of four patients with a previously undescribed LAMC3 variant. All epilepsy patients treated in Kuopio Epilepsy Center (located in Kuopio, Finland) are offered the possibility to participate in a scientific study investigating biomarkers in epilepsy (Epibiomarker study). We have collected a comprehensive database of the study population, and are currently re-evaluating our database regarding the patients with developmental and/or epileptic encephalopathy (DEE). If the etiology of epilepsy remains unknown in the clinical setting, we are performing whole exome sequencing to recognize the genetic causes. Among our study population of 323 DEE patients we recognized three patients with similar homozygous LAMC3 c.1866del (p.(Phe623Serfs*10)) frameshift variant and one patient with a compound heterozygous mutation where the same frameshift variant was combined with an intronic LAMC3 c.4231-12C>G variant on another allele. All these patients have severe epilepsy and either bilateral agyria-pachygyria or bilateral polymicrogyria in their clinical MRI scanning. Cortical malformations involve the occipital lobes in all our patients. Epilepsy phenotype is variable as two of our patients have DEE with epileptic spasms progressing to Lennox-Gastaut syndrome and intellectual disability. The other two patients have focal epilepsy without marked cognitive deficit. The four patients are unrelated. LAMC3 c.1866del p.(Phe623Serfs*10) frameshift variant is enriched in the Finnish population. Only a few patients with epilepsy caused by LAMC3 homozygous or compound heterozygous mutations have been described in the literature. To our knowledge, the variants discovered in our patients have not previously been published. Clinical phenotype appears to be more varied than previously assumed and patients with a milder phenotype and normal cognition have probably remained unrecognized.

DEPDC5 (DEP Domain-Containing Protein 5) encodes an inhibitory component of the mammalian target of rapamycin (mTOR) pathway and is commonly implicated in sporadic and familial focal epilepsies, both non-lesional and in association with focal cortical dysplasia. Germline pathogenic variants are typically heterozygous and inactivating. We describe a novel phenotype caused by germline biallelic missense variants in DEPDC5. Cases were identified clinically. Available records, including magnetic resonance imaging and electroencephalography, were reviewed. Genetic testing was performed by whole exome and whole-genome sequencing and cascade screening. In addition, immunohistochemistry was performed on skin biopsy. The phenotype was identified in nine children, eight of which are described in detail herein. Six of the children were of Irish Traveller, two of Tunisian and one of Lebanese origin. The Irish Traveller children shared the same DEPDC5 germline homozygous missense variant (p.Thr337Arg), whereas the Lebanese and Tunisian children shared a different germline homozygous variant (p.Arg806Cys). Consistent phenotypic features included extensive bilateral polymicrogyria, congenital macrocephaly and early-onset refractory epilepsy, in keeping with other mTOR-opathies. Eye and cardiac involvement and severe neutropenia were also observed in one or more patients. Five of the children died in infancy or childhood; the other four are currently aged between 5 months and 6 years. Skin biopsy immunohistochemistry was supportive of hyperactivation of the mTOR pathway. The clinical, histopathological and genetic evidence supports a causal role for the homozygous DEPDC5 variants, expanding our understanding of the biology of this gene.