OBJECTIVE: To explore the clinical characteristics and genetic basis of two Chinese pedigrees affected with Joubert syndrome. METHODS: Clinical data of the two pedigrees was collected. Genomic DNA was extracted from peripheral blood samples and subjected to high-throughput sequencing. Candidate variants were verified by Sanger sequencing. Prenatal diagnosis was carried out for a high-risk fetus from pedigree 2. RESULTS: The proband of pedigree 1 was a fetus at 23⁺⁵ weeks gestation, for which both ultrasound and MRI showed "cerebellar vermis malformation" and "molar tooth sign". No apparent abnormality was noted in the fetus after elected abortion. The fetus was found to harbor c.812+3G>T and c.1828G>C compound heterozygous variants of the INPP5E gene, which have been associated with Joubert syndrome type 1. The proband from pedigree 2 had growth retardation, mental deficiency, peculiar facial features, low muscle tone and postaxial polydactyly of right foot. MRI also revealed "cerebellar dysplasia" and "molar tooth sign". The proband was found to harbor c.485C>G and c.1878+1G>A compound heterozygous variants of the ARMC9 gene, which have been associated with Joubert syndrome type 30. Prenatal diagnosis found that the fetus only carried the c.485C>G variant. A healthy infant was born, and no anomalies was found during the follow-up. CONCLUSION The compound heterozygous variants of the INPP5E and ARMC9 genes probably underlay the disease in the two pedigrees. Above finding has expanded the spectrum of pathogenic variants underlying Joubert syndrome and provided a basis for genetic counseling and prenatal diagnosis.
Female ; Humans ; Pregnancy ; Pedigree ; Cerebellum/abnormalities* ; Abnormalities, Multiple/diagnosis* ; Eye Abnormalities/diagnosis* ; Kidney Diseases, Cystic/diagnosis* ; Phosphoric Monoester Hydrolases/genetics* ; Retina/abnormalities* ; East Asian People ; Mutation

Objective: To investigate the effects of RNA m6A demethylase ALKBH5 gene deficiency on cerebellar morphology and function in the aged mice, and to explore the role of ALKBH5 in cerebellar degeneration. Methods: Western blot was performed to detect the protein level of ALKBH5 in the cerebellum of wild-type mice of various ages. The expression of NeuN, Calbindin-D28K, MAP2, GFAP and other proteins in the cerebella of middle-aged (12-month-old) and aged (18-month-old) wild-type mice and ALKBH5^-/- mice was examined using immunohistochemistry. The balance beam test and gait analysis were performed to test the balance ability and motor coordination of the mice. Results: With aging of the mice, the expression of ALKBH5 in the cerebellum increased gradually in an age-dependent manner. In the aged mice, but not middle-aged mice, the body weight, whole brain weight and cerebellum weight of ALKBH5^-/- mice decreased by 15%, 10% and 21%, respectively (P<0.05). The expression of ALKBH5 in the Purkinje cells was much higher than that in other types of neural cells. Correspondingly, ALKBH5-deficiency caused 40% reduction in the number of Purkinje cells, as well as the length and density of neuronal dendrites in the aged mice (P<0.01). In addition, the time for the aged ALKBH5^-/- mice to pass the balance beam was 70% longer than that of the wild type mice of the same age, with unstable gaits (P<0.01). Conclusions: Gene deficiency of RNA m6A demethylase ALKBH5 causes cerebellar atrophy, Purkinje neuron loss and damage in the aged mice. These changes eventually affect mice's motor coordination and balance ability. These results suggest that imbalanced RNA m6A methylation may lead to neurodegenerative lesions in the cerebellum of mice.
Animals ; Mice ; AlkB Homolog 5, RNA Demethylase/metabolism* ; Cerebellum/metabolism* ; Methylation ; RNA/metabolism*

OBJECTIVE: To explore the clinical characteristics and genetic etiology of a patient with adolescent-onset hypomyelinated leukodystrophy with atrophy of basal ganglia and cerebellum (H-ABC). METHODS: A patient who was diagnosed with H-ABC in March 2018 at the First Affiliated Hospital of Nanjing Medical University was selected as the study subject. Clinical data was collected. Peripheral venous blood samples of the patient and his parents were collected. The patient was subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RESULTS: The patient, a 31-year-old male, had manifested with developmental retardation, cognitive decline and abnormal gait. WES revealed that he has harbored a heterozygous c.286G>A variant of the TUBB4A gene. Sanger sequencing confirmed that neither of his parents has carried the same variant. Analysis with SIFT online software indicated the amino acid encoded by this variant is highly conserved among various species. This variant has been recorded by the Human Gene Mutation Database (HGMD) with a low population frequency. The 3D structure constructed by PyMOL software showed that the variant has a harmful effect on the structure and function of the protein. According to the guidelines formulated by the American College of Medical Genetics and Genomics (ACMG), the variant was rated as likely pathogenic. CONCLUSION The c.286G>A (p.Gly96Arg) variant of the TUBB4A gene probably underlay the hypomyelinating leukodystrophy with atrophy of basal ganglia and cerebellum in this patient. Above finding has enriched the spectrum of TUBB4A gene variants and enabled early definitive diagnosis of this disorder.
Male ; Humans ; Adolescent ; Adult ; Magnetic Resonance Imaging ; Basal Ganglia/pathology* ; Cerebellum ; Atrophy/pathology* ; Mutation ; Tubulin/genetics*

OBJECTIVES: To study the clinical and genetic features of Joubert syndrome (JS) in children. METHODS: A retrospective analysis was performed on the clinical data, genetic data, and follow-up data of 20 children who were diagnosed with JS in the Department of Children's Rehabilitation, the Third Affiliated Hospital of Zhengzhou University, from January 2017 to July 2022. RESULTS: Among the 20 children with JS, there were 11 boys and 9 girls. The common clinical manifestations were developmental delay (20 children, 100%), abnormal eye movement (19 children, 95%), and hypotonia (16 children, 80%), followed by abnormal respiratory rhythm in 5 children (25%) and unusual facies (including prominent forehead, low-set ears, and triangular mouth) in 3 children (15%), and no limb deformity was observed. All 20 children (100%) had the typical "molar tooth sign" and "midline cleft syndrome" on head images, and 6 children (30%) had abnormal eye examination results. Genetic testing was performed on 7 children and revealed 6 pathogenic genes, i.e., the CPLANE1, RPGRIP1L, MKS1, CC2D2A, CEP120, and AHI1 genes. CONCLUSIONS For children with developmental delay, especially those with abnormal eye movement and hypotonia, it is recommended to perform a head imaging examination to determine the presence or absence of "molar tooth sign" and "midline cleft syndrome", so as to screen for JS to avoid missed diagnosis and misdiagnosis. There are many pathogenic genes for JS, and whole-exome sequencing can assist in the diagnosis of JS.
Male ; Female ; Humans ; Child ; Cerebellum ; Abnormalities, Multiple/genetics* ; Kidney Diseases, Cystic/genetics* ; Eye Abnormalities/genetics* ; Retina ; Retrospective Studies ; Muscle Hypotonia/genetics*

OBJECTIVES: Clinically, it has been found that some patients with epilepsy are accompanied by cerebellar atrophy that is inconsistent with symptoms, but the pattern of cerebellar atrophy after epilepsy and the role of cerebellar atrophy in the mechanism of epilepsy have not been elucidated. This study aims to explore the specific pattern of cerebellar atrophy after epilepsy via analyzing magnetic resonance images in patients with postepileptic cerebellar atrophy. METHODS: A total of 41 patients with epilepsy, who received the treatment in Xiangya Hospital of Central South University from January 2017 to January 2022 and underwent cranial MRI examination, were selected as the case group. The results of cranial MRI examination of all patients showed cerebellar atrophy. In the same period, 41 cases of physical examination were selected as the control group. General clinical data and cranial MRI results of the 2 groups were collected. The maximum area and signal of dentate nucleus, the maximum width of the brachium pontis, the maximum anterior-posterior diameter of the pontine, and the maximum transverse area of the fourth ventricle were compared between the 2 groups. The indexes with difference were further subjected to logistic regression analysis to clarify the characteristic imaging changes in patients with cerebellar atrophy after epilepsy. RESULTS: Compared with the control group, the maximum width of the brachium pontis and the maximum anterior-posterior diameter of the pontine were decreased significantly, the maximum transverse area of the fourth ventricle was increased significantly in the case group (all P<0.05). The difference in distribution of the low, equal, and high signal in dentate nucleus between the 2 groups was statistically significant (χ²=43.114, P<0.001), and the difference in the maximum area of dentate nucleus between the 2 groups was not significant (P>0.05). The maximum width of the brachium pontis [odds ratio (OR)=3.327, 95% CI 1.454 to 7.615, P=0.004] and the maximum transverse area of the fourth ventricle (OR=0.987, 95% CI 0.979 to 0.995, P=0.002) were independent factors that distinguished cerebellar atrophy after epilepsy from the normal control, while the anterior-posterior diameter of pontine (OR=1.456, 95% CI 0.906 to 2.339, P>0.05) was not an independent factor that distinguished them. CONCLUSIONS In MRI imaging, cerebellar atrophy after epilepsy is manifested as significant atrophy of the brachium pontis, significant enlargement of the fourth ventricle, and increased dentate nucleus signaling while insignificant dentate nucleus atrophy. This particular pattern may be associated with seizures and exacerbated pathological processes.
Humans ; Magnetic Resonance Imaging ; Pons ; Epilepsy/diagnostic imaging* ; Atrophy/pathology* ; Cerebellum/pathology*

Cerebellum ; Basal Ganglia

The deep cerebellar nuclei (DCN) integrate various inputs to the cerebellum and form the final cerebellar outputs critical for associative sensorimotor learning. However, the functional relevance of distinct neuronal subpopulations within the DCN remains poorly understood. Here, we examined a subpopulation of mouse DCN neurons whose axons specifically project to the ventromedial (Vm) thalamus (DCN^Vm neurons), and found that these neurons represent a specific subset of DCN units whose activity varies with trace eyeblink conditioning (tEBC), a classical associative sensorimotor learning task. Upon conditioning, the activity of DCN^Vm neurons signaled the performance of conditioned eyeblink responses (CRs). Optogenetic activation and inhibition of the DCN^Vm neurons in well-trained mice amplified and diminished the CRs, respectively. Chemogenetic manipulation of the DCN^Vm neurons had no effects on non-associative motor coordination. Furthermore, optogenetic activation of the DCN^Vm neurons caused rapid elevated firing activity in the cingulate cortex, a brain area critical for bridging the time gap between sensory stimuli and motor execution during tEBC. Together, our data highlights DCN^Vm neurons' function and delineates their kinematic parameters that modulate the strength of associative sensorimotor responses.
Animals ; Blinking ; Cerebellar Nuclei/physiology* ; Cerebellum ; Mice ; Neurons/physiology* ; Thalamus

Cerebellar Purkinje cells (PCs) exhibit two types of discharge activities: simple spike (SS) and complex spike (CS). Previous studies found that noradrenaline (NA) can inhibit CS and bidirectionally regulate SS, but the enhancement of NA on SS is overwhelmed by the strong inhibition of excitatory molecular layer interneurons. However, the mechanism underlying the effect of NA on SS discharge frequency is not clear. Therefore, in the present study, we examined the mechanism underlying the increasing effect of NA on SS firing of PC in mouse cerebellar cortex in vivo and in cerebellar slice by cell-attached and whole-cell recording technique and pharmacological methods. GABA_A receptor was blocked by 100 µmol/L picrotoxin in the whole process. In vivo results showed that NA significantly reduced the number of spikelets of spontaneous CS and enhanced the discharge frequency of SS, but did not affect the discharge frequency of CS. In vitro experiments showed that NA reduced the number of CS spikelets and after hyperpolarization potential (AHP) induced by electrical stimulation, and increased the discharge frequency of SS. NA also reduced the amplitude of excitatory postsynaptic current (EPSC) of parallel fiber (PF)-PC and significantly increased the paired-pulse ratio (PPR). Application of yohimbine, an antagonist of α2-adrenergic receptor (AR), completely eliminated the enhancing effect of NA on SS. The α2-AR agonist, UK14304, also increased the frequency of SS. The β-AR blocker, propranolol, did not affect the effects of NA on PC. These results suggest that in the absence of GABA_A receptors, NA could attenuate the synaptic transmission of climbing fiber (CF)-PC via activating α2-AR, inhibit CS activity and reduce AHP, thus enhancing the SS discharge frequency of PC. This result suggests that NA neurons of locus coeruleus can finely regulate PC signal output by regulating CF-PC synaptic transmission.
Action Potentials/physiology* ; Animals ; Cerebellar Cortex/metabolism* ; Cerebellum/metabolism* ; Mice ; Norepinephrine/pharmacology* ; Purkinje Cells/metabolism* ; Receptors, Adrenergic, alpha-2/metabolism* ; Receptors, GABA-A/metabolism*

OBJECTIVE: To analyze the phenotype and genetic variant of a fetus with dysplasia of cerebellar vermis. METHODS: Gestational status and family history of the gravida was taken in combination with the imaging results of the fetus. Following elected abortion, fetal tissue and peripheral blood samples of the couple were collected for the extraction of genome DNA. Whole exome sequencing was carried out to screen potential variant associated with the phenotype of the proband. Specific PCR primers were designed to verify the results by Sanger sequencing. RESULTS: Prenatal ultrasound revealed that the fetal vermis cerebellum was poorly developed, which was similar to the previous pregnancy. Whole exome sequencing revealed that the fetus has carried compound heterozygous variants of the CPLANE1 gene, namely c.7978C>T and c.7169delT, which were respectively inherited from the husband and wife. CONCLUSION The c.7978C>T and c.7169delT compound heterozygous variants of the CPLANE1 gene probably underlay the dysplasia of cerebellar vermis in the fetus, which has provided a basis for genetic counseling and prenatal diagnosis.
Abnormalities, Multiple/genetics* ; Cerebellum/diagnostic imaging* ; Eye Abnormalities/genetics* ; Female ; Fetus ; Humans ; Kidney Diseases, Cystic ; Mutation ; Phenotype ; Pregnancy ; Retina/abnormalities*

OBJECTIVE: To analyze the clinical phenotype and pathogenic variant in a child diagnosed with mental retardation and microcephaly with pontine and cerebellar hypoplasia (MICPCH). METHODS: Clinical phenotype of the child was reviewed. Whole exome sequencing was carried out for the child. Candidate variant was verified by Sanger sequencing of the family member. RESULTS: The proband manifested dyskinesia, development delay, cerebellar hypoplasia and bilateral hearing impairment. WES results revealed that the proband has carried a pathogenic c.1641_1644delACAA (p.Thr548Trpfs*69) variant of the CASK gene, which was verified by Sanger sequencing to be a de novo variant. CONCLUSION The c.1641_1644delACAA (p.Thr548Trpfs*69) variant of the CASK gene probably underlay the MICPCH in the proband. Above finding has provided a basis for genetic counseling. WES should be considered for the diagnosis of neurological dysplasia.
Cerebellum/abnormalities* ; Child ; Developmental Disabilities ; Family ; Humans ; Mental Retardation, X-Linked ; Microcephaly/genetics* ; Nervous System Malformations