Efficacy of Antiseizure Medications in Wolf-Hirschhorn Syndrome

Wolf-Hirschhorn syndrome (WHS) is caused by deletion of the terminal region of chromosome 4 short arm and is frequently associated with intractable epilepsy. This article evaluates the clinical features of epileptic seizures in WHS and the therapeutic efficacy of oral antiseizure medications (ASMs). Patients with WHS who were treated for epilepsy at the Saitama Children's Medical Center under 5 years of age were included. WHS was diagnosed based on genetic tests and clinical symptoms. Medical records regarding the age of onset of epilepsy, seizure type, treatment of status epilepticus (SE), and effectiveness of ASMs were retrospectively reviewed. Oral ASMs were considered effective when seizures were reduced by at least 50% compared with the premedication level. Eleven patients were included in the study. The median age at the onset of epilepsy was 9 months (range: 5-32 months). Unknown-onset bilateral tonic-clonic seizure was the most common type of seizure, occurring in 10 patients. Focal clonic seizures occurred in four patients. Ten patients exhibited recurrent episodes of SE, and its frequency during infancy was monthly in eight patients and yearly in two. SE occurrence peaked at 1 year of age and decreased after 3 years of age. The most effective ASM was levetiracetam. Although WHS-associated epilepsy is intractable with frequent SE occurrence during infancy, improvement in seizure control is expected with age. Levetiracetam may be a novel ASM for WHS.

Clinical and molecular findings in three Japanese patients with N-acetylneuraminic acid synthetase-congenital disorder of glycosylation (NANS-CDG)

We report clinical and molecular findings in three Japanese patients with N-acetylneuraminic acid synthetase-congenital disorder of glycosylation (NANS-CDG). Patient 1 exhibited a unique constellation of clinical features including marked hydrocephalus, spondyloepimetaphyseal dysplasia (SEMD), and thrombocytopenia which is comparable to that of an infant reported by Faye-Peterson et al., whereas patients 2 and 3 showed Camera-Genevieve type SMED with intellectual/developmental disability which is currently known as the sole disease name for NANS-CDG. Molecular studies revealed a maternally inherited likely pathogenic c.207del:p.(Arg69Serfs*57) variant and a paternally derived likely pathogenic c.979_981dup:p.(Ile327dup) variant in patient 1, a homozygous likely pathogenic c.979_981dup:p.(Ile327dup) variant caused by maternal segmental isodisomy involving NANS in patient 2, and a paternally inherited pathogenic c.133-12T>A variant leading to aberrant splicing and a maternally inherited likely pathogenic c.607T>C:p.(Tyr203His) variant in patient 3 (reference mRNA: NM_018946.4). The results, together with previously reported data, imply that (1) NANS plays an important role in postnatal growth and fetal brain development; (2) SMED is recognizable at birth and shows remarkable postnatal evolution; (3) NANS-CDG is associated with low-normal serum sialic acid, obviously elevated urine N-acetylmannosamine, and normal N- and O-glycosylation of serum proteins; and (4) NANS-CDG is divided into Camera-Genevieve type and more severe Faye-Peterson type.

iPSC reprogramming-mediated aneuploidy correction in autosomal trisomy syndromes

Trisomy 21, 18, and 13 are the major autosomal aneuploidy disorders in humans. They are mostly derived from chromosome non-disjunction in maternal meiosis, and the extra trisomic chromosome can cause several congenital malformations. Various genes on the trisomic chromosomes are intricately involved in the development of disease, and fundamental treatments have not yet been established. However, chromosome therapy has been developed to correct the extra chromosome in cultured patient cells, and it was recently reported that during reprogramming into iPSCs, fibroblasts from a Down syndrome patient lost the extra chromosome 21 due to a phenomenon called trisomy-biased chromosome loss. To gain preliminary insights into the underlying mechanism of trisomy rescue during the early stages of reprogramming, we reprogrammed skin fibroblasts from patients with trisomy syndromes 21, 18, 13, and 9 to iPSC, and evaluated the genomes of the individual iPSC colonies by molecular cytogenetic techniques. We report the spontaneous correction from trisomy to disomy upon cell reprogramming in at least one cell line examined from each of the trisomy syndromes, and three possible combinations of chromosomes were selected in the isogenic trisomy-rescued iPSC clones. Single nucleotide polymorphism analysis showed that the trisomy-rescued clones exhibited either heterodisomy or segmental uniparental isodisomy, ruling out the possibility that two trisomic chromosomes were lost simultaneously and the remaining one was duplicated, suggesting instead that one trisomic chromosome was lost to generate disomic cells. These results demonstrated that trisomy rescue may be a phenomenon with random loss of the extra chromosome and subsequent selection for disomic iPSCs, which is analogous to the karyotype correction in early preimplantation embryos. Our finding is relevant for elucidating the mechanisms of autonomous karyotype correction and future application in basic and clinical research on aneuploidy disorders.

Use of Perampanel and a Ketogenic Diet in Nonketotic Hyperglycinemia: A Case Report

BACKGROUND

Nonketotic hyperglycinemia is a severe form of early onset epileptic encephalopathy caused by disturbances in the glycine cleavage system; the neurological damage is mainly attributed to overstimulation of the N-methyl-D-aspartate receptor.

CASE

The patient presented with a severe form of nonketotic hyperglycinemia and experienced frequent epileptic spasms and focal seizures, which were resistant to vigabatrin, adrenocorticotropic hormone therapy, and combined dextromethorphan and sodium benzoate treatments. By 9 months of age, perampanel reduced epileptic spasms by >50%. At 14 months of age, the ketogenic diet markedly reduced focal seizures and glycine levels in the cerebrospinal fluid.

CONCLUSION

Perampanel reduced fast excitatory neuronal activity, which was induced by an α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor, followed by prolonged electrical depolarizations due to an N-methyl-D-aspartate receptor. Furthermore, the ketogenic diet may have modulated the excessive neurotoxic cascade through the N-methyl-D-aspartate receptor. Perampanel and ketogenic diet were effective for seizure control in our patient.

Possible mitochondrial dysfunction in a patient with deafness, dystonia, and cerebral hypomyelination (DDCH) due to BCAP31 Mutation

Background

Deafness, dystonia, and cerebral hypomyelination (DDCH) is an X‐linked disorder due to hemizygous mutations of BCAP31.

Methods

We report an 8‐year‐old boy with DDCH who possibly accompanied mitochondrial dysfunction. Clinical evaluation, respiratory chain enzyme assay, and whole exome sequencing analysis were performed.

Results

Mitochondrial dysfunction was suspected by respiratory chain enzyme assay on his cultured skin fibroblasts which showed significantly decreased complex I enzyme activity. Whole exome sequencing analysis revealed a recurrent BCAP31 mutation (c.97C>T:p.Gln33*) which confirmed the diagnosis of DDCH for the patient.

Conclusion

We speculate that mitochondrial dysfunction may be a feature in patients with DDCH.

l-Thyroxine-responsive drop attacks in childhood benign hereditary chorea: A case report

Benign hereditary chorea (BHC) is a rare autosomal dominant disease that is characterized by non-progressive chorea with early-childhood-onset, congenital hypothyroidism, and neonatal respiratory distress. Although tetrabenazine and levodopa are partly effective for chorea and drop attacks in some patients, there is no standard treatment option. We herein describe a childhood case of BHC that presented with l-thyroxine-responsive drop attacks. A genetic analysis revealed an interstitial deletion that included two enhancer regions of NKX2-1, providing genetic confirmation of BHC. This is the first report to inform the connection between thyroid function and drop attacks in BHC. Moreover, our findings identify l-thyroxine as a therapeutic option for the management of drop attacks in BHC.

Mice with an Oncogenic HRAS Mutation are Resistant to High-Fat Diet-Induced Obesity and Exhibit Impaired Hepatic Energy Homeostasis

Costello syndrome is a “RASopathy” that is characterized by growth retardation, dysmorphic facial appearance, hypertrophic cardiomyopathy and tumor predisposition. > 80% of patients with Costello syndrome harbor a heterozygous germline G12S mutation in HRAS. Altered metabolic regulation has been suspected because patients with Costello syndrome exhibit hypoketotic hypoglycemia and increased resting energy expenditure, and their growth is severely retarded. To examine the mechanisms of energy reprogramming by HRAS activation in vivo, we generated knock-in mice expressing a heterozygous Hras G12S mutation (Hras^G12S/+ mice) as a mouse model of Costello syndrome. On a high-fat diet, Hras^G12S/+ mice developed a lean phenotype with microvesicular hepatic steatosis, resulting in early death compared with wild-type mice. Under starvation conditions, hypoketosis and elevated blood levels of long-chain fatty acylcarnitines were observed, suggesting impaired mitochondrial fatty acid oxidation. Our findings suggest that the oncogenic Hras mutation modulates energy homeostasis in vivo.

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Mice expressing Hras G12S (Hras^G12S/+) showed Costello syndrome-like phenotypes, including craniofacial and cardiac defects.

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Hras^G12S/+ mice are resistant to high-fat diet (HFD)-induced obesity, showing microvesicular hepatic steatosis.

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Upon fasting, HFD-fed Hras^G12S/+ mice show abnormal hepatic fatty acid oxidation, hypoketosis and early hypoglycemia.

Costello syndrome is a congenital anomaly syndrome, which is caused by germline mutations in HRAS oncogene. Altered metabolic regulation has been suspected because patients with Costello syndrome exhibit hypoketotic hypoglycemia and increased resting energy expenditure, and growth retardation. Here, we generated a mouse model for Costello syndrome expressing a Hras G12S mutation, which showed craniofacial and heart abnormalities. On a high-fat diet, mutant mice exhibited a lean phenotype with poor weight gain and microvesicular hepatic steatosis. Under starvation conditions, impaired mitochondrial fatty acid oxidation has been observed. These results suggest that oncogenic RAS signaling in mice modulates energy homeostasis in vivo.

NOTCH2 Hajdu-Cheney Mutations Escape SCFFBW7-Dependent Proteolysis to Promote Osteoporosis

Hajdu-Cheney syndrome (HCS), a rare autosomal disorder caused by heterozygous mutations in NOTCH2, is clinically characterized by acro-osteolysis, severe osteoporosis, short stature, neurological symptoms, cardiovascular defects, and polycystic kidneys. Recent studies identified that aberrant NOTCH2 signaling and consequent osteoclast hyperactivity are closely associated with the bone-related disorder pathogenesis, but the exact molecular mechanisms remain unclear. Here, we demonstrate that sustained osteoclast activity is largely due to accumulation of NOTCH2 carrying a truncated C terminus that escapes FBW7-mediated ubiquitination and degradation. Mice with osteoclast-specific Fbw7 ablation revealed osteoporotic phenotypes reminiscent of HCS, due to elevated Notch2 signaling. Importantly, administration of Notch inhibitors in Fbw7 conditional knockout mice alleviated progressive bone resorption. These findings highlight the molecular basis of HCS pathogenesis and provide clinical insights into potential targeted therapeutic strategies for skeletal disorders associated with the aberrant FBW7/NOTCH2 pathway as observed in patients with HCS.

Adult mice expressing a Braf Q241R mutation on an ICR/CD-1 background exhibit a cardio-facio-cutaneous syndrome phenotype

Activation of the RAS pathway has been implicated in oncogenesis and developmental disorders called RASopathies. Germline mutations in BRAF have been identified in 50-75% of patients with cardio-facio-cutaneous (CFC) syndrome, which is characterized by congenital heart defects, distinctive facial features, short stature and ectodermal abnormalities. We recently demonstrated that mice expressing a Braf Q241R mutation, which corresponds to the most frequent BRAF mutation (Q257R) in CFC syndrome, on a C57BL/6J background are embryonic/neonatal lethal, with multiple congenital defects, preventing us from analyzing the phenotypic consequences after birth. Here, to further explore the pathogenesis of CFC syndrome, we backcrossed these mice onto a BALB/c or ICR/CD-1 genetic background. On a mixed (BALB/c and C57BL/6J) background, all heterozygous Braf(Q241R/+) mice died between birth and 24 weeks and exhibited growth retardation, sparse and ruffled fur, liver necrosis and atrial septal defects (ASDs). In contrast, 31% of the heterozygous Braf(Q241R/+) ICR mice survived over 74 weeks. The surviving Braf(Q241R/+) ICR mice exhibited growth retardation, sparse and ruffled fur, a hunched appearance, craniofacial dysmorphism, long and/or dystrophic nails, extra digits and ovarian cysts. The Braf(Q241R/+) ICR mice also showed learning deficits in the contextual fear-conditioning test. Echocardiography indicated the presence of pulmonary stenosis and ASDs in the Braf(Q241R/+) ICR mice, which were confirmed by histological analysis. These data suggest that the heterozygous Braf(Q241R/+) ICR mice show similar phenotypes as CFC syndrome after birth and will be useful for elucidating the pathogenesis and potential therapeutic strategies for RASopathies.

New BRAF knockin mice provide a pathogenetic mechanism of developmental defects and a therapeutic approach in cardio-facio-cutaneous syndrome

Cardio-facio-cutaneous (CFC) syndrome is one of the 'RASopathies', a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS-MAPK pathway. Germline mutations in BRAF cause CFC syndrome, which is characterized by heart defects, distinctive facial features and ectodermal abnormalities. To define the pathogenesis and to develop a potential therapeutic approach in CFC syndrome, we here generated new knockin mice (here Braf(Q241R/+)) expressing the Braf Q241R mutation, which corresponds to the most frequent mutation in CFC syndrome, Q257R. Braf(Q241R/+) mice manifested embryonic/neonatal lethality, showing liver necrosis, edema and craniofacial abnormalities. Histological analysis revealed multiple heart defects, including cardiomegaly, enlarged cardiac valves, ventricular noncompaction and ventricular septal defects. Braf(Q241R/+) embryos also showed massively distended jugular lymphatic sacs and subcutaneous lymphatic vessels, demonstrating lymphatic defects in RASopathy knockin mice for the first time. Prenatal treatment with a MEK inhibitor, PD0325901, rescued the embryonic lethality with amelioration of craniofacial abnormalities and edema in Braf(Q241R/+) embryos. Unexpectedly, one surviving pup was obtained after treatment with a histone 3 demethylase inhibitor, GSK-J4, or NCDM-32b. Combination treatment with PD0325901 and GSK-J4 further increased the rescue from embryonic lethality, ameliorating enlarged cardiac valves. These results suggest that our new Braf knockin mice recapitulate major features of RASopathies and that epigenetic modulation as well as the inhibition of the ERK pathway will be a potential therapeutic strategy for the treatment of CFC syndrome.

Autopsy study of cerebellar degeneration in siblings with ataxia-telangiectasia-like disorder

Ataxia-telangiectasia-like disorder (ATLD) is caused by mutations of the MRE11 gene and is characterized by cerebellar ataxia, increased frequency of chromosomal translocations and hypersensitivity to ionizing radiation. ATLD is a rare genetic disease and the associated pathological changes in the brain are unclear. Here, we report the neuropathological findings in the first cases of genetically confirmed ATLD in a pair of Japanese male siblings. Magnetic resonance imaging studies performed during infancy revealed that both subjects had cerebellar atrophy. They died of pulmonary cancer at 9 and 16 years. The siblings had the same compound heterozygous mutations of the MRE11 gene. Brain autopsy demonstrated mild and severe cerebellar atrophy in the vermis and medial part of the hemispheres, oral to the horizontal fissure, respectively. Nuclear immunoreactivity for MRE11 was absent in neurons of cerebellar cortex, cerebral cortex, basal ganglia and midbrain, whereas being widespread in normal control brains. Immunoreactivity for the DNA oxidative stress marker, 8-hydroxy-2'-deoxyguanosine, was identified in nuclei of granule cells and Bergmann glial cells. The combination of MRE11 deficiency and DNA oxidative injury might have led to selective cerebellar degeneration.