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Organic light-emitting diodes (OLEDs) employing a single active layer potentially offer a number of benefits compared to multilayer devices; reduced number of materials and deposition steps, potential for solution processing, and reduced operating voltage due to the absence of heterojunctions. However, for single-layer OLEDs to achieve efficiencies approaching those of multilayer devices, balanced charge transport is a prerequisite. This requirement excludes many efficient emitters based on thermally activated delayed fluorescence (TADF) that exhibit electron trapping, such as the green-emitting bis(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)methanone (DMAC-BP). By employing a recently developed trap-free large band gap material as a host for DMAC-BP, nearly balanced charge transport is achieved. The single-layer OLED reaches an external quantum efficiency (EQE) of 19.6%, which is comparable to the reported EQEs of 18.9-21% for multilayer devices, but achieves a record power efficiency for DMAC-BP OLEDs of 82 lm W -1 , clearly surpassing the reported multilayer power efficiencies of 52.9-59 lm W -1 . In addition, the operational stability is greatly improved compared to multilayer devices and the use of conventional host materials in combination with DMAC-BP as an emitter. Next to the obvious reduction in production costs, single-layer OLEDs therefore also offer the advantage of reduced energy consumption and enhanced stability., (© 2024 The Authors. Advanced Materials published by Wiley‐VCH GmbH.)

Donor-π-acceptor fluorophores that consist of an electron-donating amino group and an electron-accepting triarylborane moiety generally exhibit substantial solvatochromism in their fluorescence while retaining high fluorescence quantum yields even in polar media. Herein, we report a new family of this compound class, which bears ortho-P(=X)R 2 -substituted phenyl groups (X=O or S) as a photodissociative module. The P=X moiety that intramolecularly coordinates to the boron atom undergoes dissociation in the excited state, giving rise to dual emission from the corresponding tetra- and tricoordinate boron species. The susceptibility of the systems to photodissociation depends on the coordination ability of the P=O and P=S moieties, whereby the latter facilitates dissociation. The intensity ratios of the dual emission bands are sensitive to environmental parameters, including temperature, solution polarity, and the viscosity of the medium. Moreover, precise tuning of the P(=X)R 2 group and the electron-donating amino moiety led to single-molecule white emission in solution., (© 2023 Wiley-VCH GmbH.)

Olefin-borane π-complexes have been postulated as intermediates for the addition of frustrated Lewis pairs (FLP) to olefins. In the present study, we have employed this weak interaction to modulate the electronic properties of boron-based π-electron materials. A series of donor-π-acceptor (D-π-A) fluorophores that contain an alkenyl-bridged diarylboryl group is synthesized. A crystallographic analysis revealed that the olefin and boron moieties are held in close proximity. Upon addition of a Lewis base to a solution of these D-π-A fluorophores, an FLP-type addition occurs with concurrent significant changes in the absorption and emission properties. The FLP-type reaction shifts the reaction site from the Lewis-acidic boron atom to a carbocationic center, and thereby even facilitates a reaction with bulky Lewis bases. For example, a tricyclohexylphosphine adduct thus generated exhibits temperature-dependent reversible dissociation/association behavior. These results provide a design strategy for stimuli-responsive emissive boron-based materials., (© 2022 Wiley-VCH GmbH.)

We studied the photophysical and electroluminescent (EL) characteristics of a series of azaborine derivatives having a pair of boron and nitrogen aimed at the multi-resonance (MR) effect. The computational study with the STEOM-DLPNO-CCSD method clarified that the combination of a BN ring-fusion and a terminal carbazole enhanced the MR effect and spin-orbit coupling matrix element (SOCME), simultaneously. Also, we clarified that the second triplet excited state (T 2 ) plays an important role in efficient MR-based thermally activated delayed fluorescence (TADF). Furthermore, we obtained a blue-violet OLED with an external EL quantum efficiency (EQE) of 9.1%, implying the presence of a pronounced nonradiative decay path from the lowest triplet excited state (T 1 )., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer GX declared a past co-authorship with the author CA to the handling editor., (Copyright © 2022 Bae, Sakai, Tsuchiya, Ando, Chen, Nguyen, Chan, Lee, Auffray, Nakanotani, Yamaguchi and Adachi.)

Two kinds of planarized phenyldithienylboranes, which contain (CH 3 ) 2 C- or CH 2 -bridging moieties, were synthesized. The difference of the bridging moieties affects their packing structures and photophysical properties. In particular, the (CH 3 ) 2 C-bridged derivative exhibits a large Stokes shift, unusual for such planarized compounds, that results from a large structural relaxation in the excited state. A series of π-extended derivatives was synthesized, among which a p-(diphenylamino)phenyl-substituted derivative shows large solvatochromism in the fluorescence spectra, while maintaining high quantum yields even in polar solvents. The Lewis acidity of the phenyldithienylborane derivatives was also assessed by titration with pyridine. The Lewis acidity of the boron center is affected not only by the difference in the steric bulk of the bridging moieties, but also by the electronic effect of the substituents introduced at remote positions relative to the boron atom. These results demonstrate the characteristic features of planarized phenyldithienylboranes as building blocks for boron-based π-electron materials., (© 2022 Wiley-VCH GmbH.)

We report on the fluorescence properties of a new class of emissive and stable π-radicals that contain a boron atom at a position distant from the radical center. A fully planarized derivative exhibited an intense red fluorescence with high fluorescence quantum yields (Φ F >0.67) even in polar solvents. To elucidate the origin of this phenomenon, we synthesized another boron-stabilized radical that contains a bulky aryl group on the boron atom. A comparison of these derivatives, as well as with conventional donor-π-acceptor (D-π-A)-type emissive π-radicals, unveiled several characteristic features in their photophysical properties. A theoretical analysis revealed that the SOMO-LUMO electronic transition generates an emissive D 1 state. Unlike conventional D-π-A-type π-radicals, this state does not undergo significant structural relaxation. The boron-stabilized π-radicals demonstrated promising potential for organic light-emitting diodes as an emitting material., (© 2022 Wiley-VCH GmbH.)

We report a new design strategy for an excited-state intramolecular proton transfer (ESIPT) fluorophore that can be used in acidic media. A photobasic pyridine-centered donor-acceptor-donor-type fluorophore is combined with a basic trialkylamine "strap". In the presence of an acid, protonation occurs predominantly at the amine moiety in the ground state. A single-crystal X-ray diffraction analysis confirmed the formation of a pre-organized intramolecular hydrogen-bonded structure between the resulting ammonium moiety and the pyridine ring. Upon excitation, the intramolecular charge-transfer transition increases the basicity of the pyridine moiety in the excited state, resulting in proton transfer from the amine to the pyridine moiety. Consequently, the fluorophore takes on a polymethine-dye character in the ESIPT state, which gives rise to significantly red-shifted emission with an increased fluorescence quantum yield., (© 2021 Wiley-VCH GmbH.)

Planarized triarylboranes are attracting increasing attention not only as models of boron-doped graphenes, but also as promising materials for organic optoelectronics. In particular, polycyclic aromatic hydrocarbon (PAH) skeletons with embedded boron atom(s) in the inner positions are of importance in light of their high chemical stability and π-stacking ability derived from their planar geometries. Herein, we disclose a robust synthesis of such fully fused boron-doped PAHs and their self-assembly behavior in aqueous media to explore their potential utility in biological applications. The synthesis using in situ- generated planar diarylboranes as a key precursor afforded a series of fully fused boron-doped PAHs, even including an amphiphilic derivative with hydrophilic side chains. These compounds exhibited red emission in solution, and slight structural modification resulted in increased fluorescence brightness. While these compounds showed relatively low Lewis acidity compared to their partially ring-fused counterparts, their Lewis acidities were slightly increased in polar solvents compared to those in nonpolar solvents. In addition, their B-N Lewis acid-base adducts, even those with a strong, charge-neutral Lewis base such as N , N -dimethylaminopyridine (DMAP), exhibited photo-dissociation behavior in the excited state. The amphiphilic derivative showed significant spectral changes with increased water content in DMSO/H 2 O mixed media and formed sheet-like aggregates. The disassembly and assembly processes of the aggregates were externally controlled by the addition of DMAP and an acid, accompanied by a change in the fluorescence intensity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Electron-deficient heteroacenes that contain two tricoordinate boron atoms in their acene skeletons and planarized phenyl ether moieties at their periphery were synthesized via the borylation of silicon-bridged precursors. X-ray crystallographic analysis revealed quinoidal structures, which give rise to two-step reversible redox processes for both the reduction and oxidation. These compounds exhibit intense absorption and sharp fluorescence bands with vibronic structures in the near-infrared (NIR) region. These properties originate from the push-pull effect along the long axis of the molecule derived from the electron-donating ether moieties and the electron-accepting boron moieties. Of particular note is the NIR emission of the thienothiophene-centered heteroacene, which has a maximum at 952 nm with a narrow band width of 309 cm -1 in cyclohexane. A Franck-Condon analysis revealed the crucial role of the sterically less-hindered thienothiophene spacer in achieving this sharp emission band., (© 2021 Wiley-VCH GmbH.)

Background: Variants in the type IV collagen gene ( COL4A1/2 ) cause early-onset cerebrovascular diseases. Most individuals are diagnosed postnatally, and the prenatal features of individuals with COL4A1/2 variants remain unclear., Methods: We examined COL4A1/2 in 218 individuals with suspected COL4A1 /2-related brain defects. Among those arising from COL4A1/2 variants, we focused on individuals showing prenatal abnormal ultrasound findings and validated their prenatal and postnatal clinical features in detail., Results: Pathogenic COL4A1/2 variants were detected in 56 individuals (n=56/218, 25.7%) showing porencephaly (n=29), schizencephaly (n=12) and others (n=15). Thirty-four variants occurred de novo (n=34/56, 60.7%). Foetal information was available in 47 of 56 individuals, 32 of whom (n=32/47, 68.1%) had one or more foetal abnormalities. The median gestational age at the detection of initial prenatal abnormal features was 31 weeks of gestation. Only 14 individuals had specific prenatal findings that were strongly suggestive of features associated with COL4A1/2 variants. Foetal ventriculomegaly was the most common initial feature (n=20/32, 62.5%). Posterior fossa abnormalities, including Dandy-Walker malformation, were observed prenatally in four individuals. Regarding extrabrain features, foetal growth restriction was present in 16 individuals, including eight individuals with comorbid ventriculomegaly., Conclusions: Prenatal observation of ventriculomegaly with comorbid foetal growth restriction should prompt a thorough ultrasound examination and COL4A1/2 gene testing should be considered when pathogenic variants are strongly suspected., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Heteroatom doping is a powerful strategy to alter the electronic structure of polycyclic aromatic hydrocarbons (PAHs). Especially boron doping endows PAH scaffolds with electron-accepting character and Lewis acidic centers. Herein, we report that embedding a five-membered borole ring into a polycyclic skeleton imparts the π-system with antiaromatic character and thereby induces unique properties and behavior. A series of borole-embedded π-conjugated compounds were synthesized from teraryl precursors via a borylation/intramolecular electrophilic C-H borylation sequence. The obtained compounds exhibit planar structures with distorted geometries around the boron center and form columnar slipped face-to-face π-stacked structures. Among these compounds, a pyrene-fused derivative shows an intense emission with a high quantum yield in solution. This compound also exhibits high Lewis acidity, which reflects the antiaromatic character and strained structure of the borole substructure. This compound forms a Lewis acid-base adduct even with weakly Lewis basic phosphorus-containing polycyclic π-systems. Analyzing the crystal structure of the thus-obtained adduct revealed a complex between the boron- and phosphorus-embedded π-systems with a direct B-P dative bond. This complex undergoes photodissociation in the excited state and exhibits an emission exclusively from the base-free borole-embedded π-system.

We report the kinetically controlled supramolecular polymerization of boron-containing π-conjugated molecules, which was enabled by a seeding method based on dual trapping of a metastable state by synergistic intramolecular hydrogen bonding and Lewis acid-based complexation. Planarized triarylborane-based 1 , which bears a diamide chain with chiral alkyl groups, was synthesized. Upon cooling, the solution of monomer 1 afforded a supramolecular polymerization in a cooperative manner to form helical supramolecular nanostructures with intense J-type aggregate emission. In the presence of pyridine, the triarylborane moiety formed a Lewis acid-base complex, which enhances the stabilization of the metastable monomeric state. An assembly incompetent structure with a folded diamide chain conformation and a pyridine moiety axially coordinated to the boron atom is responsible for slowing the spontaneous aggregation. The seeding method was successfully applied to the solution to produce homogeneous nanofibers even at a high (millimolar-level) concentration. This unprecedented kinetic control via dual trapping provides an effective method to achieve seed-initiated polymerization under concentrated conditions.

The synthesis and photophysical properties of a soluble amide-embedded coronene is reported. The key step in this synthesis is the twofold C-H activation of diazaperylene by a rhodium(III)Cp* catalyst. This unprecedented structural motif shows intense fluorescence in the near infrared region with a small Stokes shift and a distinct vibronic structure, which exhibits a slight extent of negative solvatochromism. Comparison of this compound with some relevant compounds revealed the importance of the amide incorporation in the peripheral concave region including an angular position to retain high aromaticity reflecting that of parent coronene. Treatment of this compound with Lewis acid B(C 6 F 5 ) 3 formed a bis-adduct, which exhibited enhanced aromaticity as a consequence of the increased double bond character of the amide C-N bonds., (© 2020 Wiley-VCH GmbH.)

Dimesitylboron-functionalized stilbene derivatives have been found to undergo an unusual regioselective photoisomerization upon irradiation at 365 nm. Using NMR to follow the photoreaction, the structures of key reaction intermediates and the final products were established. This photoisomerization occurs in four steps: trans-cis isomerization, Diels-Alder reaction, di-π-methane rearrangement, and ring opening with [1,3]-H migration. This results in the formation of a rare structure with three fused five-membered rings and a six-membered one.

Bora-fluoresceins ( BF s), fluorescein analogues containing a tricoordinate boron atom instead of an oxygen atom at the 10-position of the fluorescein skeleton, were synthesized as a new family of fluorescein analogues. The deprotonated BF s exhibited absorption and fluorescence in the near-infrared region, which were significantly red-shifted relative to those of hitherto-known heteroatom-substituted fluorescein analogues on account of the orbital interaction between the tricoordinate boron atom and the fluorescein skeleton. BF s also showed multi-stage changes resulting from a Lewis acid-base equilibrium at the boron center in combination with a Brønsted acid-base equilibrium at the phenolic hydroxy group., (This journal is © The Royal Society of Chemistry 2019.)

A B,N-diphenyl-5,10-dihydro-dibenzo-1,4-azaborine, in which both phenyl groups on the boron and nitrogen atoms are planarized to generate a carbazole substructure, was synthesized. The structral constraint around the boron and nitrogen atoms alters the π-conjugation mode and thus the photophysical and electrochemical properties. Specifically, this structurally constrained dibenzoazaborine showed an intense blue emission with a narrow full width at half maximum. One of its derivatives exhibited near infrared absorption in the one-electron-oxidized state.

Ozonated water (OW) is presently used as a chemical disinfectant in many fields, due to its versatile antimicrobial properties. As ozone rapidly decomposes to oxygen, especially in the presence of organic matter, it is important to estimate the authentic antimicrobial activity of OW in the presence of contaminants. However, the effect of contaminants on the antimicrobial activity of OW has not been fully investigated. To address this, we evaluated the effect of protein contaminants on the antimicrobial activity of OW. The survival rate of each tested microorganism excluding Bacillus subtilis spores was reduced to less than 0.1%, when the microorganism suspension was exposed to 9.1 ppm of OW for 15 s in the presence of 0.0045% protein. Our study therefore suggests that approximately 10 ppm of OW can reduce the survival rates of almost all microorganisms in the presence of proteins.

Microcephaly-capillary malformation syndrome is a congenital and neurodevelopmental disorder caused by biallelic mutations in the STAMBP gene. Here we identify the novel homozygous mutation located in the SH3 binding motif of STAMBP (NM_006463.4) (c.707C>T: p.Ser236Phe) through whole-exome sequencing. The case patient was a 2-year-old boy showing severe global developmental delay, progressive microcephaly, refractory seizures, dysmorphic facial features, and multiple capillary malformations. Immunoblot analysis of patient-derived lymphoblastoid cell lines (LCLs) revealed a severe reduction in STAMBP expression, indicating that Ser236Phe induces protein instability. STAMBP interacts with the SH3 domain of STAM and transduces downstream signals from the Jaks-STAM complex. The substitution of Ser236Phe found in the case patient was located in the SH3-binding motif, and we propose the mutation may block STAM binding and subsequently induce STAMBP degradation. Contrary to previously reported STAMBP mutations, the Ser236Phe mutation did not lead to constitutive activation of the PI3K-AKT-mTOR pathway in patient-derived LCLs, as indicated by the expression of phosphorylated S6 ribosomal protein, suggesting that it is not the major pathomechanism underlying the disorder in this patient.

A B-phenyldibenzo[b,f]borepin planarized with two methylene bridges was synthesized. The structural constraint on the B-phenyl group resulted in a bathochromic shift of the absorption and fluorescence properties as well as enhanced Lewis acidity. A donor-π-acceptor type derivative based on this scaffold exhibited intense fluorescence irrespective of the solvent polarity.

Patients with a mutation at Arg756 in ATP1A3 have been known to exhibit a distinct phenotype, characterized by prolonged weakness and encephalopathy, triggered by febrile illness. With only eight reports published to date, more evidence is required to correlate clinical features with a mutation at Arg756. Here we report an additional case with an Arg756Cys mutation in ATP1A3. A four-year-old boy showed mild developmental delay with recurrent paroxysmal episodes of weakness and encephalopathy from nine months of age. Motor deficits, which included bilateral hypotonia, ataxia, dysmetria, limb incoordination, dysarthria, choreoathetosis, and dystonia, were observed from one year and three months. Whole-exome sequencing detected a heterozygous de novo variant at c.2266C>T (p.Arg756Cys) in ATP1A3. The episodic course and clinical features of this case were consistent with previously reported cases with mutations at Arg756. Furthermore, his phenotype of marked ataxia was more similar to that of an Arg756Cys patient with relapsing encephalopathy and cerebellar ataxia syndrome, than to those with Arg756His and Arg756Leu mutations. This report therefore provides evidence of genotype-phenotype correlations in ATP1A3-related disorders as well as in patients with mutations at Arg756 in ATP1A3., (Copyright © 2017 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

A new reaction mode for triarylboranes under photochemical conditions was discovered. Photoirradiation of dimesitylboryl-substituted (hetero)arenes produced spirocyclic boraindanes, where one of the C-H bonds in the ortho-methyl groups of the mesityl substituents was formally added in a syn fashion to a C-C double bond of the (hetero)aryl group. Quantum chemical calculations and laser flash photolysis measurements indicated that the reaction proceeds through a [1,6]-sigmatropic rearrangement. This behavior is reminiscent of the photochemical reaction mode of arylalkenylketones, thus demonstrating the isosteric relation between tricoordinate organoboron compounds and the corresponding pseudo-carbocationic species in terms of pericyclic reactions. Despite the disrupted π-conjugation, the resulting spirocyclic boraindanes exhibited a characteristic absorption band at relatively long wavelengths (λ=370-400 nm)., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aims: Patients with chronic liver disease sometimes develop cholestasis, which induces severe whole-body pruritus that may disrupt daily activities and sleep. To determine the efficacy of nalfurafine hydrochloride (5 μg), which is a selective κ-opioid receptor agonist, in improving pruritus, we undertook a double-blind placebo-controlled study in patients with chronic liver disease with refractory pruritus. Nalfurafine hydrochloride at 2.5 μg was also used to evaluate the dose-response relationship., Methods: In total, 318 subjects were randomly assigned to receive the placebo or nalfurafine hydrochloride (2.5 or 5 μg) given orally once daily for 84 consecutive days. Pruritus was assessed based on the visual analog scale and pruritus scores., Results: Changes in the visual analog scale at week 4 (last observation carried forward) were significantly greater in the nalfurafine hydrochloride groups at 28.56 and 27.46 mm in the 2.5 μg and 5 μg groups, respectively, compared to 19.25 mm in the placebo group (P = 0.0022 and 0.0056, respectively). The major adverse drug reactions (ADRs) included pollakiuria (including nocturia), somnolence, insomnia (including middle insomnia), and constipation. Most ADRs were mild., Conclusions: Nalfurafine hydrochloride (2.5 or 5 μg daily) was effective in the treatment of refractory pruritus in patients with chronic liver disease. Furthermore, no clinically significant ADRs were observed at either dose., (© 2016 The Authors. Hepatology Research published by John Wiley & Sons Australia, Ltd on behalf of Japan Society of Hepatology.)

We encountered two children with acute encephalopathy associated with unique clinical manifestations. Both the patients had status epilepticus at onset and neuroimaging studies revealed marked brain edema and bilateral thalamic lesions. Although they were treated with steroids and immunoglobulin, their outcomes were very poor. A thermolabile variant of carnitine palmitoyltransferase II and an elevated interleukin-6 level in cerebrospinal fluid were observed in one patient each. The constellation of clinical and neuroimaging findings in our patients is apparently not consistent with any established subtype of acute encephalopathy/encephalitis., (Georg Thieme Verlag KG Stuttgart · New York.)

Vigabatrin (VGB) is one of the most effective anti-epileptic drugs for tonic spasms, those accompanied with tuberous sclerosis complex (TSC), but is not available in Japan. We treated 7 patients with West syndrome (WS) and TSC with VGB. In these patients, VGB treatment was started at 5-65 months of age. Six patients (86%) had complete cessation of tonic spasms. Of these, 3 patients had complete cessation within 24 hours after VGB treatment. The mean initial dosage of VGB was 36.2 mg x kg(-1) x day(-1), and the mean maintenance dosage was 38.4 mg x kg(-1) x day(-1). At the beginning of VGB treatment, 3 patients had hypsarrhythmia, 2 had focal discharge with generalization, and 2 had only focal discharge on electroencephalography. Hypsarrhythmia disappeared within 4-8 weeks after VGB treatment. Behavioral problems and sleep difficulty were observed in 6 patients. Visual field examination revealed no abnormalities in 3 patients. We hope that patients with WS and TSC can be treated with VGB as soon as possible in Japan.

Rotavirus, one of the major causes of severe gastroenteritis in children, occasionally causes central nervous system complications. Recently several patients with acute encephalitis/encephalopathy due to rotavirus associated with cerebellar signs and symptoms have been reported. The condition is characterized by disturbances of consciousness at onset and cerebellar signs and symptoms such as hypotonia, ataxia, dysmetria, and speech disorders, including mutism, slow speech, and dysarthria at convalescence. We report two patients (3-year-old girl, 2-year-old boy) who developed acute encephalitis due to rotavirus and showed cerebellar signs and symptoms. Both patients had characteristic history of consciousness disturbances subsequent to several days of diarrhea, vomiting and fever, and cerebellar symptoms such as hypotonia, ataxia, dysmetria, and speech disorders during the recovery period. Electroencephalography showed diffuse high-voltage delta wave activity in each patient. Brain magnetic resonance imaging showed cerebellar edema in the acute phase followed by cerebellar atrophy on follow-up images in both patients. In the first patient, diffusion-weighted images (DWI) revealed high signals at the left cerebellar peduncle region and apparent diffusion coefficient (ADC) maps showed decreased ADC values of the lesion in the acute phase. The first patient had dysmetria at 1-year follow-up. However, she had normal motor and cognitive functions and could lead her daily life without impairment. In the second patient, no further symptoms were apparent at 1-year follow-up. Acute encephalitis/encephalopathy due to rotavirus with cerebellar signs and symptoms might be diagnosed on DWI, by demonstrating decreased ADC values in acute phase.

Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) is a rare leukoencephalopathy first described by van der Knaap in 2002. Diffuse cerebral hypomyelination and atrophy of the basal ganglia and cerebellum characterize H-ABC. We report a 9-year-old Japanese boy with H-ABC who had been suspected to have Pelizaeus Merzbacher disease. Brain MRI revealed delayed myelination, however, no other remarkable abnormal laboratory findings were found. PLP1 gene mutation was not detected and he had no nystagmus. He was diagnosed as having H-ABC at the age of 8 years because of supratentorial hypomyelination and progressive atrophy of the basal ganglia and cerebellum on the follow-up MRI. This boy's condition was clinically more severe than those with other reported patients with H-ABC.

CYP2C19 is a clinically important enzyme involved in the metabolism of therapeutic drugs such as (S)-mephenytoin, omeprazole, proguanil, and diazepam. Individuals can be characterized as either extensive metabolizers (EM) or poor metabolizers (PM) on the basis of CYP2C19 enzyme activity. The PM phenotype occurs in 2-5% of Caucasian populations, but at higher frequencies (18-23%) in Asians. CYP2C19*2 and CYP2C19*3, which are single-nucleotide polymorphisms of CYP2C19, are the main cause of PM phenotyping in homozygotes or compound heterozygotes. We report two novel mutations in the CYP2C19 gene identified by direct sequencing and subcloning procedures. One of these mutations was considered to be CYP2C19*3 by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). This result suggests that mutations classed as CYP2C19*3 might include other mutations. Further studies are needed to clarify the relationship between these novel mutations and enzyme activity.