OBJECTIVE: To explore the clinical characteristics and genetic etiology of a child with Aicardi-Goutières syndrome 3 (AGS3). METHODS: Trio whole exome sequencing was carried out for the child and his parents, and candidate variants were verified by Sanger sequencing. To further clarify their pathogenicity, the crystal structure of the variants was simulated and analyzed, and the plasmid of variants was expressed in vitro. A literature search was also carried out to summarize the phenotypic and genetic characteristics of AGS3. RESULTS: The child was found to harbor novel compound heterozygous variants of the RNASEH2C gene, namely c.434G>T (p.Arg145Leu) and c.494G>C (p.Ter165Ser), which were inherited from his mother and father, respectively. Analysis of protein crystal structure suggested that the c.434G>T (p.Arg145Leu) variant may affect the stability of local structure, and in vitro experiments showed that this variant can lead to protein degradation. The c.494G>C (p.Ter165Ser) variant has destroyed the stop codon, resulting in prolonged variant. CONCLUSION The novel compound heterozygous variants of the RNASEH2C gene probably underlay the AGS3 in this child, which has enriched the phenotypic and mutational spectrum of this disorder.
Humans ; Child ; Mutation ; Autoimmune Diseases of the Nervous System/genetics* ; Nervous System Malformations/genetics*

OBJECTIVE: To assess the value of chromosomal microarray analysis (CMA) for the diagnosis of fetuses with anomalies of the central nervous system (CNS) and summarize the outcome of the pregnancies and follow-up. METHODS: A total of 636 fetuses from June 2014 to December 2020 who were referred to the Prenatal Diagnosis Center of Nanjing Drum Tower Hospital due to abnormal CNS prompted by ultrasound were selected as the research subjects. Based on the ultrasound findings, the fetuses were divided into ventricular dilatation group (n = 441), choroid plexus cyst group (n = 41), enlarged posterior fossa group (n = 42), holoprosencephaly group (n = 15), corpus callosum hypoplasia group (n = 22), and other anomaly group (n = 75). Meanwhile, they were also divided into isolated (n = 504) and non-isolated (n = 132) groups based on the presence of additional abnormalities. Prenatal samples (amniotic fluid/chorionic villi/umbilical cord blood) or abortus tissue were collected for the extraction of genomic DNA and CMA assay. Outcome of the pregnancies and postnatal follow-up were summarized and subjected to statistical analysis. RESULTS: In total 636 fetuses with CNS anomalies (including 89 abortus tissues) were included, and 547 cases were followed up. The overall detection rate of CMA was 11.48% (73/636). The detection rates for the holoprosencephaly group, ACC group, choroid plexus cyst group, enlarged posterior fossa group, ventricular dilatation group and other anomaly group were 80% (12/15), 31.82% (7/22), 19.51% (8/41), 14.29% (6/42), 7.48% (33/441) and 9.33% (7/75), respectively. Compared with the isolated CNS anomaly group, the detection rate for the non-isolated CNS anomaly group was significantly higher (6.35% vs. 31.06%) (32/504 vs. 41/132) (χ² = 62.867, P < 0.001). Follow up showed that, for 52 fetuses with abnormal CMA results, 51 couples have opted induced labor, whilst 1 was delivered at full term with normal growth and development. Of the 434 fetuses with normal CMA results, 377 were delivered at full term (6 had developmental delay), and 57 couples had opted induced labor. The rate of adverse pregnancy outcome for non-isolated CNS abnormal fetuses was significantly higher than that of isolated CNS abnormal fetuses (26.56% vs. 10.54%) (17/64 vs. 39/370) (χ² = 12.463, P < 0.001). CONCLUSION Fetuses with CNS anomaly should be tested with CMA to determine the genetic cause. Most fetuses with negative CMA result have a good prognosis, but there is still a possibility for a abnormal neurological phenotype. Fetuses with CNS abnormalities in conjunct with other structural abnormalities are at increased risk for adverse pregnancy outcomes.
Female ; Pregnancy ; Humans ; Holoprosencephaly ; Prenatal Diagnosis/methods* ; Central Nervous System ; Fetus/abnormalities* ; Nervous System Malformations/genetics* ; Microarray Analysis ; Central Nervous System Diseases ; Cysts ; Chromosome Aberrations ; Ultrasonography, Prenatal/methods*

Non-coding RNAs (ncRNAs) are a class of functional RNAs that play critical roles in different diseases. NcRNAs include microRNAs, long ncRNAs, and circular RNAs. They are highly expressed in the brain and are involved in the regulation of physiological and pathophysiological processes of central nervous system (CNS) diseases. Mounting evidence indicates that ncRNAs play key roles in CNS diseases. Further elucidating the mechanisms of ncRNA underlying the process of regulating glial function that may lead to the identification of novel therapeutic targets for CNS diseases.
Humans ; RNA, Untranslated/genetics* ; MicroRNAs/genetics* ; RNA, Long Noncoding/genetics* ; RNA, Circular ; Central Nervous System Diseases/genetics*

The serine/threonine p21-activated kinases (PAKs), as main effectors of the Rho GTPases Cdc42 and Rac, represent a group of important molecular switches linking the complex cytoskeletal networks to broad neural activity. PAKs show wide expression in the brain, but they differ in specific cell types, brain regions, and developmental stages. PAKs play an essential and differential role in controlling neural cytoskeletal remodeling and are related to the development and fate of neurons as well as the structural and functional plasticity of dendritic spines. PAK-mediated actin signaling and interacting functional networks represent a common pathway frequently affected in multiple neurodevelopmental and neurodegenerative disorders. Considering specific small-molecule agonists and inhibitors for PAKs have been developed in cancer treatment, comprehensive knowledge about the role of PAKs in neural cytoskeletal remodeling will promote our understanding of the complex mechanisms underlying neurological diseases, which may also represent potential therapeutic targets of these diseases.
Animals ; Cytoskeleton/genetics* ; Humans ; Nervous System Diseases/genetics* ; Neurons/enzymology* ; Signal Transduction ; p21-Activated Kinases/metabolism*

OBJECTIVE: Distal hereditary motor neuropathy (dHMN) comprises a heterogeneous group of inherited disorders associated with neurodegeneration of motor nerves and neurons, mainly charac-terized by progressive atrophy and weakness of distal muscle without clinical or electrophysiological sensory abnormalities. To improve the recognition and diagnosis of the disease, we summarized the clinical manifestations, electrophysiological, pathological, and genetic characteristics in eight patients with dHMN. METHODS: Eight probands from different families diagnosed with dHMN were recruited in this study between June 2018 and April 2019 at Peking University People's Hospital. Eight patients underwent complete neurological examination and standard electrophysiological examinations. The clinical criteria were consistent with the patients presenting with a pure motor neuropathy with no sensory changes on electrophysiology. The detailed clinical symptoms, neurophysiological examinations, pathological features and gene mutations were analyzed retrospectively. Genetic testing was performed on the eight patients using targeted next-generation sequencing panel for inherited neuromuscular disorder and was combined with segregation analysis. RESULTS: The age of onset ranged between 11 and 64 years (median 39.5 years) in our dHMN patients. All the cases showed a slowly progressive disease course, mainly characterized by distal limb muscle weakness and atrophy. The motor nerve conduction revealed decreased compound muscle action potential amplitude and velocity, while the sensory nerve conduction velocities and action potentials were not affected. Needle electromyography indicated neurogenic chronic denervation in all patients. Muscle biopsy performed in two patients demonstrated neurogenic skeletal muscle damage. Sural nerve biopsy was performed in one patient, Semithin sections shows relatively normal density and structure of large myelinated fibers, except very few fibers with thin myelin sheaths, which suggested very mild sensory nerve involvement. Eight different genes known to be associated with dHMN were identified in the patients by next-generation sequencing, pathogenic dHMN mutations were identified in three genes, and the detection rate of confirmed genetic diagnosis of dHMN was 37.5% (3/8). Whereas five variants of uncertain significance (VUS) were identified, among which two novel variants co-segregated the phenotype. CONCLUSION dHMN is a group of inherited peripheral neuropathies with great clinical and genetic heterogeneity. Next-generation sequencing is widely used to discover pathogenic genes in patients with dHMN, but more than half of the patients still remain genetically unknown.
Adolescent ; Adult ; Child ; Hereditary Sensory and Motor Neuropathy/genetics* ; Humans ; Middle Aged ; Mutation ; Peripheral Nervous System Diseases ; Phenotype ; Retrospective Studies ; Young Adult

OBJECTIVE: To explore the clinical features and genetic variant in a child featuring megalencephalic leukoencephalopathy with subcortical cyst (MLC) type 2B. METHODS: Clinical and imaging data of the child was collected. Potential variant of hepatocyte adhesion molecule (HEPACAM) gene was detected by Sanger sequencing. The growth and development of her mother and uncle was also reviewed. RESULTS: The patient, a 1-year-and-7-month female, presented with convulsion, mental retardation and abnormally increased head circumference. Cranial MRI revealed extensive long T1 long T2 signals in the white matter of bilateral cerebral hemisphere, right anterior sac cyst, cerebral gyrus widening, and shallow sulcus. Sanger sequencing identified a c.437C>T missense variant in exon 3 of the HEPACAM gene. The same variant was detected in her mother but not father. Her mother and maternal uncle both had a history of increased head circumference when they were young. In their adulthood, the head circumference was in the normal range but still greater than the average. CONCLUSION The heterozygous variant of the HEPACAM gene probably underlies the MLC2B in this child. The variant has derived from her asymptomatic mother, which suggested incomplete penetrance of the MLC2B.
Adult ; Cell Cycle Proteins ; genetics ; Cerebrum ; diagnostic imaging ; Cysts ; diagnostic imaging ; genetics ; Female ; Genetic Variation ; Hereditary Central Nervous System Demyelinating Diseases ; diagnostic imaging ; genetics ; Humans ; Infant

OBJECTIVE: To explore the clinical, electrophysiological and imaging features of a patient with Krabbe disease caused by GALC mutation. METHODS: A comprehensive analysis including clinical investigation and genetic testing was carried out. RESULTS: The patient presented with peripheral neuropathy with electrophysiological anomaly suggestive of asymmetric demyelinating neuropathy. Brain imaging revealed leukoencephalopathy. Genetic analysis has identified compound heterozygous mutations in exons 5 and 11 of the GALC gene, namely c.461C>A and c.1244G>A. CONCLUSION Krabbe disease is a group of disorders featuring substantial phenotypic heterogeneity. Genetic and enzyme testing has become indispensable for accurate diagnosis for this disease.
DNA Mutational Analysis ; Galactosylceramidase ; genetics ; Genetic Testing ; Humans ; Leukodystrophy, Globoid Cell ; complications ; genetics ; Mutation ; Peripheral Nervous System Diseases ; etiology

Central Nervous System Diseases ; etiology ; Child ; Female ; Humans ; Infant ; Lymphohistiocytosis, Hemophagocytic ; complications ; diagnosis ; genetics ; Magnetic Resonance Imaging ; Male ; Mutation ; Perforin ; genetics

BACKGROUND AND PURPOSE: A thick corpus callosum (TCC) can be associated with a very grave outcome in fetuses, but its clinical presentation in older children seems to be markedly different. METHODS: The corpus callosum (CC) was defined as thick based on observations and impressions. We reviewed cases of children who were diagnosed as TCC based on brain magnetic resonance imaging (MRI) studies. The pertinent clinical data of these children were collected, and their CCs were measured. RESULTS: Out of 2,552 brain MRI images, those of 37 children were initially considered as showing a TCC. Those initial imaging were reviewed by an experienced neuroradiologist, who confirmed the diagnosis in 34 children (1.3%): 13 had neurofibromatosis-1 (NF-1), 9 had epilepsy, 3 had macrocephaly capillary malformation (MCM) syndrome, 3 had autistic spectrum disorder, 1 had a Chiari-1 malformation, and 1 had increased head circumference. No specific neurologic disorder could be defined in seven children. The measured thickness of the CC in these children was comparable to those published in the literature for adults. CONCLUSIONS: A TCC is a rare brain malformation that can be found in neuropathologies with apparently diverse pathognomonic mechanisms, such as NF-1 and MCM. It is not necessarily associated with life-threatening conditions, instead being a relatively benign finding, different in nature from that reported in fetuses.
Adult ; Brain ; Capillaries ; Child* ; Corpus Callosum* ; Diagnosis ; Epilepsy ; Fetus ; Genetics ; Head ; Humans ; Magnetic Resonance Imaging ; Megalencephaly ; Nervous System Diseases ; Neurofibromatoses ; Neuropathology

OBJECTIVETo detect potential mutation of MLC1 gene in a child affected with megalencephalic leukoencephalopathy with subcortical cysts (MLC).

METHODSClinical symptoms of the patient were retrieved. Peripheral blood DNA samples from the patient, her parents and healthy controls were collected. Potential mutation of the MLC1 gene was detected by polymerase chain reaction and Sanger sequencing.

RESULTSThe patient presented with severe motor developmental delay and a giant skull. Magnetic resonance scan showed diffuse white matter swelling in bilateral hemispheres. DNA sequencing identified a novel homozygous c.177-c.180delC mutation of the MLC1 gene. The parents of the patient both carried a heterozygous mutation c.177-c.180delC but had a normal phenotype.

CONCLUSIONA novel MLC1 mutation c.177-c.180delC has been identified in a patient with MLC. The mutation is presumably disease-causing and has derived from parents who are both carriers.

Child, Preschool ; Cysts ; genetics ; Female ; Hereditary Central Nervous System Demyelinating Diseases ; genetics ; Humans ; Membrane Proteins ; genetics ; Mutation