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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.

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 (HrasG12S/+ mice) as a mouse model of Costello syndrome. On a high-fat diet, HrasG12S/+ 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.

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., Deafness, dystonia, and cerebral hypomyelination (DDCH) is an X‐linked disorder due to hemizygous mutations of BCAP31. Mitochondrial dysfunction may be associated with DDCH.

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.

Genetic mosaicism for somatic mutations of oncogenes is common in genodermatoses, which can be complicated with extra-cutaneous abnormalities. Here we describe an infant with a congenital anaplastic astrocytoma, a linear syringocystadenoma papilliferum, and ocular abnormalities. The BRAF c.1799T>A p.V600E mutation was detected in both the brain and skin tumor cells but not in the blood or normal skin cells, suggesting somatic mosaicsism for the mutation. Clinically, the brain tumor gradually became life threatening without any response to conventional chemotherapies including carboplatin, etoposide, and temozolomide. Vemurafenib, a BRAF p.V600E inhibitor, was administered daily after the detection of the BRAF mutation. This single-agent therapy was dramatically effective against the anaplastic astrocytoma; the tumor regressed, the cerebrospinal fluid cell count and protein levels decreased to normal levels, and hydrocephalus resolved. Moreover, other lesions including a corneal cyst also responded to vemurafenib. The brain tumor continued shrinking after 6 months of treatment. We present a genodermatosis syndrome associated with BRAF c.1799T>A p.V600E mosaicism. This syndrome may represent a new entity in the mosaic RASopathies, partly overlapping with Schimmelpenning-Feuerstein-Mims syndrome, which is driven by mosaicism of HRAS and/or KRAS activating mutations. Screening for BRAF c.1799T>A p.V600E is especially useful for those with malignant tumors, because it is one of the most-druggable targets.