Tubulin proteins form microtubules, which are critical for neuronal cell migration. In humans, there are at least 27 tubulin genes. Pathogenic variants in these genes cause tubulinopathies, which are characterized by diverse neurodevelopmental symptoms and brain malformations. This study analyzed the genetic variants and clinical characteristics of 12 patients (3 males, 9 females) with confirmed β-tubulinopathies. A retrospective chart review indicated that diagnoses were made via exome, genome, or targeted next-generation panel sequencing. Most patients (11/12) showed significant developmental delay and hypotonia. Other neurological symptoms included ocular motility disorders (7/12), ataxia (6/12), seizures (3/12), and microcephaly (2/12). The median age at symptom onset was 10 months (range 0 - 24). Corpus callosum abnormalities were the most common brain malformation, present in 10 patients, including one case of complete agenesis. Basal ganglia abnormalities and cerebellar hypoplasia were each observed in 9 patients. Cortical abnormalities, white matter changes, and brainstem hypoplasia were each present in 8 patients. Severe lissencephaly was not observed. Ten pathogenic or likely pathogenic missense variants were identified in five β-tubulin genes (TUBB2A, TUBB2B, TUBB3, TUBB4A, and TUBB5). Most variants were de novo, but one was a maternally inherited variant, c.211 G > A in TUBB3, which was associated with milder features. A novel variant in TUBB2A, c.1234 G > A p.(Glu412Lys), was also identified. These genetic variations were associated with a broad phenotypic spectrum of β-tubulinopathies, including complex brain malformations and neurodevelopmental disorders. Despite its rarity, tubulinopathy may be considered in the differential diagnosis for patients presenting with developmental delay and brain malformations.

Mutations in the reelin (RELN) extracellular matrix protein gene are known to cause cortical and cerebellar malformations due to disruption of normal neuroblast migration and localization during fetal neurodevelopment. More recently, mutations in genes encoding transmembrane receptors involved in the recognition of reelin, including very low-density lipoprotein receptor (VLDLR), have been linked to various dysequilibrium and ataxia syndromes. Radiologic findings in cases of VLDLR mutations include cerebellar hypoplasia with marked vermis hypoplasia and cortical simplification without lissencephaly. However, the gross and histologic findings in VLDLR-related cerebellar hypoplasia in humans have yet to be described in the literature. Neuropathologic analysis of a confirmed human case could serve to illuminate unique findings and further elucidate the underlying pathophysiologic mechanism of VLDLR gene mutations. We report the autopsy neuropathological findings in a genetically confirmed third-trimester gestation fetal example.

Lissencephaly is a genetically heterogeneous condition caused by aberrant neuronal migration. Cerebellar hypoplasia has been commonly associated in some subtypes of lissencephaly, notably the tubulinopathies. CDK5 is a microtubule-associated protein, and its defective function has been implicated in various neurodevelopmental and neurodegenerative disorders. Biallelic loss-of-function variant in CDK5 has been reported to cause lissencephaly type 7 in a single family to date. We describe an infant with diffuse agyria, cerebellar hypoplasia, and agenesis of the corpus callosum harboring a homozygous novel missense variant c.149G>A in CDK5. She had refractory seizures, pyramidal signs, microcephaly, and growth failure. She did not achieve any developmental milestones and succumbed at 4 months of age. The disease course and severity were similar to those observed in the patients in the first report, who had a splicing defect leading to loss-of-function. In silico functional analysis showed that the variant c.149G>A (p.Arg50Gln) caused instability of the CDK5 protein structure, potentially causing functional disruption. Functional analysis of the p.Arg50Gln variant, using a yeast complementation assay, showed a deleterious impact of the variant. In conclusion, this is the second family with CDK5-related lissencephaly type 7.

Prenatal diagnosis of fetal central nervous system (CNS) anomalies remains challenging and is influenced by various factors, including imaging equipment quality, and access to advanced modalities such as fetal magnetic resonance imaging (MRI). In resource-limited settings, these constraints highlight the need for practical and accessible screening methods. This study aims to evaluate the predictive value of the fetal corpus callosum length-to-head circumference (CCL/HC) and corpus callosum length-to-occipitofrontal (CCL/OFD) diameter ratios in the detection of fetal central CNS abnormalities. This prospective cohort study included 243 singleton pregnancies undergoing routine mid-trimester ultrasound between November 2024 and May 2025. 15 fetuses with CNS anomalies confirmed by fetal MRI constituted the patient group. Diagnosed anomalies included schizencephaly, lissencephaly, vermian agenesis, cerebellar hypoplasia, hydrocephalus, pachygyria, septo-optic dysplasia, and corpus callosum (CC) malformations, particularly hypoplasia. After excluding 22 cases with non-CNS anomalies, maternal diseases, or intrauterine growth restriction, 206 fetuses comprised the control group. The CCL/HC and CCL/OFD ratios were then calculated for analysis and compared between groups. A total of 221 fetuses were analyzed; CNS anomalies were confirmed in 15 of them, while 206 served as the control group. In the anomaly group, the mean corpus callosum length (CCL) was significantly shorter compared to healthy fetuses (19.27 ± 3.03 mm vs. 23.33 ± 3.50 mm; p < 0.001). Both the CCL/HC and CCL/OFD ratios were significantly lower in fetuses with CNS anomalies (p < 0.001 for both). ROC analysis showed AUC values of 0.833 for CCL/HC and 0.935 for CCL/OFD; the cutoff values were 0.0953 and 0.2658, respectively, with both ratios demonstrating high specificity (99.5%) for anomaly detection. Additionally, both ratios exhibited a moderate positive correlation with gestational age in the control group and remained within the ± 2 standard deviation limits in 97% (CCL/HC) and 95.7% (CCL/OFD) of healthy fetuses. Fetal CCL/OFD and CCL/HC ratios may offer a practical method for both assessing normal CC development and identifying potential CNS anomalies.

Lissencephaly and cerebellar hypoplasia (LCH) represents a spectrum of congenital developmental malformations of the cerebral cortex and cerebellum, mostly occurring as inherited conditions caused by variants in an increasingly recognized number of genes. LCH has been identified in three Dorset-cross lambs with congenital neurological signs in Australia. Lambs were unable to walk and had reduced vision, and one lamb developed a hypermetric gait and intention tremors. Grossly, the lambs had diffuse pachygyria with reduction in white matter, mild bilateral ventriculomegaly of the lateral ventricles, and a markedly hypoplastic cerebellum. Histologically, there was disorganization of neurons within the cerebral cortex and hippocampus. The cerebellar vermis had disorganized, thin, and hypocellular gray matter with frequent ectopic Purkinje cells, while identifiable folia were largely absent within the hemispheres. Luxol fast blue stain and glial fibrillary acidic protein, neuronal nuclear protein, synaptophysin, and neuron-specific enolase immunohistochemistry confirmed the thickened, disorganized cerebral cortical gray matter and reduced white matter. Within the cerebellum, immunohistochemistry demonstrated marked dysplasia. Whole-genome sequencing analysis and prediction of variant effects identified a missense variant of interest in the candidate gene reelin (RELN; NC_040255.1:g.50288685C>T; NM_001306121.1:c.7088G>A; NP_001293050.1:p.(R2363H)) with a deleterious Sorting Intolerant from Tolerant (SIFT) score. Sanger sequencing identified that the variant segregated with LCH disease in the 3 affected individuals, their sire, and 6 unaffected flock members. The NP_001293050.1: p.(R2363H) substitution is predicted to decrease the stability of the protein (ΔΔG = -1.55 kcal/mol). Pathological and genetic findings are consistent with previously described phenotypes of RELN variants in Churra sheep, dogs, and humans.