Long-term effects of recurrent neonatal seizures on neurobehavioral function and related gene expression and its intervention by inhibitor of cathepsin B.

Cathepsins are families of proteases that have been reported to play the key roles in neuroexcitotoxicity. The present study was sought to determine the effect of CBI, a cathepsin B inhibitor, in the prevention of neurobehavioral deficits after inhalant flurothyl-induced recurrent neonatal seizures in rats. We examined the expression pattern of autophagy-related genes at acute phase after the last seizures using western blot method, and evaluated behavioral deficits during postnatal day 28 (P28) to P35. The results showed improved neurological scores and learning ability in CBI-treated rats compared with the nontreated control. Flurothyl-induced increases in the ratio of LC3-II/LC3-I, Beclin-1 and Cathepsin-B were blocked by pre-treatment with CBI at 1.5, 3, 6 and 24 h after the last seizures in hippocampus and cerebral cortex by western blot analysis. Meanwhile, CBI also reversed flurothyl-induced down-regulation of Bcl-2 protein levels. Furthermore, in the long-term time point of 35 days (P35), PRG-1 mRNA and protein level in hippocampus and cerebral cortex of recurrent seizure group were up-regulated when compared to the control rats; meanwhile, the up-regulated expression of PRG-1 were robustly inhibited by CBI. These date demonstrated, for the first time, that lysosomal enzymes participate in neonatal seizure-induced brain damage and that modulation of cathepsin B may offer a new strategy for the development of therapeutic interventions for treatment of developmental seizure-induced brain damage.

[Genetic and phenotypic characteristics of SCN1A mutations in Dravet syndrome].

OBJECTIVE: To study SCN1A gene mutations and their inheritance in patients with Dravet syndrome(DS), and to analyze the phenotypes of their family members and genotype-phenotype correlations. METHODS: Genomic DNA was extracted from peripheral blood samples from 181 DS patients and their parents. Phenotypes of affected members were analyzed. SCN1A gene mutations were screened using PCR-DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) RESULTS: SCN1A gene mutations were identified in 128 patients (70.7%), which included 60 missense mutations (46.9%), 55 truncation mutations (43.0%), 10 splice site mutations (7.8%), and 3 cases with SCN1A gene fragment deletions or duplications(2.3%). Five patients (3.9%) had mutations inherited from one of their parents. One father has carried a somatic mutation mosaicism (C373fsx378). For the 5 parents carrying a mutation, 1 had febrile seizures, 2 had febrile seizures plus, 1 had afebrile generalized tonic-clonic seizures, whilst 1 was normal. CONCLUSION: The mutation rate of SCN1A in DS patients is about 70%. Most mutations are of missense and truncation mutations. Only a few patients have carried fragment deletions or duplications. Most SCN1A mutations are de novo, only a few were inherited from the parents. SCN1A mutations carried by the parents can be in the form of mosaicism. The phenotypes of parents with SCN1A mutations are either mild or normal.

[Association of genetic polymorphisms in methionine metabolism genes with X-linked adrenoleukodystrophy].

OBJECTIVE: To investigate the association of the polymorphisms of methionine metabolism genes and the phenotype of X-linked adrenoleukodystrophy (X-ALD) and clinical severity. METHODS: The clinical information of 120 X-ALD patients were analyzed and three genetic variants involved in the methionine metabolism, including cystathionine beta-synthase (CBS) c.844_855ins68, 5-methyltetrahydrofolate-homocysteine-S-methyltransferase (MTR) c.2756A to G, and transcobalamin 2 (TC2) c.776 C to G were analyzed by polymerase chain reaction and sequencing. The association between these polymorphisms and phenotype of X-ALD was studied. RESULTS: The frequency of GG genotype of the TC2 c.776 C/G was higher in patients with central nervous system(CNS) demyelination than in controls (P= 0.012). However, the other two polymorphisms did not show any significant associations with the phenotypes. CONCLUSION: The GG genotype of TC2 c.776 C/G may contribute to X-ALD phenotype.

[Clinical and mutation analysis of a Chinese family with muscle eye brain disease].

OBJECTIVE: To study the clinical feature of a Chinese family with muscle-eye-brain disease (MEB) and the mutation of protein O-linked-mannose beta-1, 2-N-acetylglucosaminyltransferase 1 gene (POMGNT1). METHODS: Clinical data of the proband and his family members were collected. Genomic DNA from the patient and his parents was extracted using standard procedures from the peripheral blood leukocytes. Polymerase chain reaction and DNA direct sequencing were employed to analyze all of the exons to determine the mutation, and the relationship between genotype and phenotype was analyzed. RESULTS: The proband was diagnosed as floppy baby, presented with delayed psychomotor development and myopathic face. His serum creatine kinase (CK) level elevated moderately and brain MRI showed cerebral and cerebellar gyrus abnormalities with white matter signal intensity changes, cerebellar cysts and cerebellar and brain stem hypoplasia, consistent with congenital muscular dystrophy with eye brain disorder. Further test with DNA detected a compound heterozygous mutation of c.1896 1 G to C before exon 22 which may induce splicing error, and missense mutation c.1319T to G, p.L440R in exon 16. Both parents had a heterozygous mutation at the mutation sites. CONCLUSION: According to our study, the family is diagnosed as MEB. The proband carried compound heterozygous mutations in the POMGNT1 gene, and his parents are heterozygous carriers, which is consistent with autosomal recessive inheritance. The child is definitely diagnosed as having muscle eye brain disease.

[Clinical characteristics of Huntington disease in two pedigrees and analysis of expanded CAG trinucleotide repeat].

OBJECTIVE: To understand the clinical and genetic features of Huntington disease (HD). METHODS: The clinical data of HD cases from 2 Chinese families were analyzed and trinucleotide repeat in the IT15 gene were investigated in 9 of the two families by polymerase chain reaction and GeneScan. RESULTS: Among the two pedigrees, 6 cases were ascertained as HD by genetic test. Genotypes of IT15 were heterozygous in these HD patients. CAG repeat of the patients in the HD chromosome were 40-78. In the two pedigrees, the onset age was earlier in the subsequent generations than that of their fathers. In pedigree 2, the onset age was inversely correlated with CAG repeat number. One out of the 6 cases was juvenile-onset type of Huntington disease, whose clinical symptoms were different from those of the adult-onset cases, especially the hypertonic manifestation. CONCLUSION: HD is an autosomal dominant neurodegenerative disorder with genetic anticipation caused by enlargement of CAG repeat in IT15 gene. The clinical manifestation is different between the juvenile-onset and the adult-onset. The number of CAG repeat is inversely correlated with the onset age and clinical severity.

[Clinical characteristics and follow-up management of 135 children with myasthenia gravis].

OBJECTIVE: To investigate and analyze the clinical manifestations, classification, therapeutic approaches and follow-up of myasthenia gravis (MG) in children in order to improve its management and prognosis. METHODS: Clinical information of 135 children with MG, who were diagnosed between January 1993 to January 2008, were collected and retrospectively analyzed. And prospective following-up of these patients were conducted. RESULTS: Among the 135 cases, 59 were males and 76 females, giving the ratio of M/F around 1:1.3. Totally, 115 cases (85.2%) were type I MG (ocular type), of which only 4.2% developed to generalized type during the subsequent clinical course. Type II MG (generalized type)was found in 18 cases (13.4%) and type III MG in two cases(1.5%). The onset age ranged from 5 month to 15 years, with 50.3% before three years and 80.7% before seven years. Upper respiratory tract infection was presented in 26.7% (36/135) of the sick children before the onset of MG. Among the 106 children being followed up, recurrence of the disease identified in 50.9% and the number of relapse ranged from 1 to 9. Altogether, 40.19% (43/106) of the cases were positive for anti-acetylcholine receptor antibodies (AchR-Ab) on the initial examination, and the AchR-Ab postitive rate showed no difference among different clinical subtypes and states. However, during the follow-up, 53% (9/17) of the recurrent cases, who were negative at the first onset, turned to be positive, and 37.97% (30/79) were positive for repetitive nerve stimulation in electromyogram test. There were 71 % (45/63) of all the cases showed reduced levels of CD4+ and/or CD3+ and/or CD8+. Thymus proliferation was found in 5.93% (8/135) through CT scan and thymoma in 1.48% (2/135). Steroids and anti-cholinesterase administration were effective in most cases with good prognosis. CONCLUSION: Childhood MG, mainly type I, is relatively common in China, with specific characteristics which are different from western patients or adult MG in morbidity, sex distribution, progress, laboratory examination and treatment. The prevalence of myasthenia gravis crisis and mortality rate in MG children is low, and few are accompanied with thymoma. Most MG cases have a satisfied prognosis and few have neuropsychic sequela.

[Analysis of the parental origin of MECP2 mutations in patients with Rett syndrome].

OBJECTIVE: To identify the parental origin of methyl-CpG-binding protein 2 (MECP2) gene mutations in Chinese patients with Rett syndrome. METHODS: Single nucleotide polymorphisms (SNPs) in intron 3 of the MECP2 gene were analyzed by PCR and sequencing in 115 patients with Rett syndrome. Then sequencing of the SNP region was performed for the fathers of the patients who had at least one SNP, to determine which allele was from the father. Then allele-specific PCR was performed and the products were sequenced to see whether the allele from father or mother harbored the mutation. RESULTS: Seventy-six of the 115 patients had at least one SNP. Three hot SNPs were found in these patients. They were: IVS3+22C >G, IVS3+266C >T and IVS3+683C>T. Among the 76 cases, 73 had a paternal origin of MECP2 mutations, and the other 3 had a maternal origin. There were multiple types of MECP2 mutation of the paternal origin, including 4 frame shift, 2 deletion and 67 point (56C >T, 6C >G, 2A >G, 2G >T and 1A >T) mutations. The mutation types of the 3 patients with maternal origin included 2 frame shift and 1 point (C >T) mutation. CONCLUSION: In Chinese RTT patients, the MECP2 mutations are mostly of paternal origin.

[Genotype, phenotype analysis and follow-up study on patients with Duchenne/Becker muscular dystrophy].

OBJECTIVE: To improve the diagnosis and management of Duchenne/Becker muscular dystrophy(DMD/BMD). METHODS: Clinical features of 90 cases of DMD/BMD were collected. Genomic DNA was extracted using standard procedures from the peripheral blood leukocytes, and multiplex ligation-dependent probe amplification (MLPA) was applied to detect DMD gene to identify genetic mutation. For those patients whose deletion/duplication mutation was not identified, FKRP gene mutation analysis was performed using PCR-DNA direct sequence. All the cases were followed up. RESULTS: Among the 90 cases of clinically diagnosed DMD/BMD, exons deletion of DMD was detected in 58 cases (64.44%), and exons duplication in 9 (10.00%). Among the 34 mothers with an affected boy but without previous genetic conformation, 17 were confirmed to be carriers with gene deletion/duplication. None of the 23 cases, without detected DMD gene deletion/duplication, carried FKRP gene mutation. Fourteen children were given short-term intermittent prednisone therapy (0.75 mg/kg daily during the first 10 days of each month). The course was not long enough and the sample size was too small to conclude any benefits or side effects. Prenatal diagnosis was provided for one mother in her next pregnancy detecting a female carrier fetus. CONCLUSION: DMD gene deletions mainly occurs between exons 45 and 54, while duplications mostly at 5'-terminus. Identification of the characteristics and types of gene mutation may facilitate the recognition and prognosis prediction of DMD/BMD. MLPA is a non-complex and quick diagnostic tool for DMD/BMD and its carriers, and also helpful in genetic counseling.

ZnT-1, ZnT-3, CaMK II, PRG-1 expressions in hippocampus following neonatal seizure-induced cognitive deficit in rats.

Epilepsy in children is associated with a broad spectrum of cognitive deficits, which is associated with hippocampal mossy fiber sprouting. The underlying molecular mechanisms involved in mossy fiber sprouting in hippocampus following developmental seizures are not completely known. We studied the timing of cognitive dysfunction following neonatal seizures and the relation of this cognitive impairment to zinc transporter 1 (ZnT-1), 3 (ZnT-3), calcium/calmodulin-dependent protein kinase II (CaMK II), plasticity-related gene 1 (PRG-1) expression in hippocampus. A seizure was induced by inhalant flurothyl daily in neonatal Sprague-Dawley rats from postnatal day 6 (P6). Rats were assigned into the single-seizure group (SS), the recurrent-seizure group (RS, seizures induced in six consecutive days), and the control group. During P41-P46 and P85-P90, the rats were tested for spatial learning and memory abilities with automatic Morris water maze task. At P90, mossy fiber sprouting and gene expression in hippocampus were determined subsequently by Timm staining and RT-PCR methods. The escape latencies from the water maze were significantly longer in rats of RS group than those of the control and SS groups at d4 of the first maze test and at d3, d4 of the second maze test. As far as Spatial Probe Test was concerned, the frequency of passing through the platform quadrant was significantly decreased in RS group than that in control and SS groups in the entire two probe tests. In rats with recurrent seizures (RS group), there was an increased distribution of Timm granules in both the supragranular region of the dentate gyrus and the stratum pyramidale of CA3 subfield in RS group, while remaining barely visible in control and SS groups; the Timm scores in CA3 and dentate gyrus in the RS animals were significantly higher than that in the control and SS groups. RT-PCR densitometry analysis showed that the ratios of hippocampal ZnT-1 to beta-actin of SS and RS group were decreased significantly compared with that of control group. Meanwhile, CaMK II to beta-actin of RS group was markedly lower compared with those of SS and control groups. Our results suggest that the long-term adverse effects of recurrent neonatal seizures on cognition and mossy fiber sprouting may be associated with the down-regulated expression of ZnT-1 and CaMK II in hippocampus.

[An improved method for primary culture of rat cortical neuron and cell identification].

OBJECTIVE: To improve previous method of primary rat cortical neuron culture to get purer and more long-lasting cells for study. METHODS: Timed-pregnant Wistar rats at a gestational age of 16 or 17 days (16-17 d) were used. Fetal brains were removed and the cerebral cortices were dissected out. Papain digestion and mechanical dissociation were combined to conduct mono-cell suspending media. Four to six hours (4-6 h) post-plating, all plating media were removed from cultures and replaced with Neurobasal medium supplemented with B27. On the third day, 10 mumol/L cytosine arabinoside (Ara-C) was added to the culture for 24 h to inhibit the outgrowth of glial cells. Half of the culture medium was changed every week. The morphological changes of neuron cells were observed by light microscope. Double immuno-staining of microtubule-associated protein 2 (MAP2) and karyon were applied to assess the culture purity. Evaluation of synapse formation was processed by immunocytochemical analysis using antibodies against both pre- and postsynaptic protein markers. RESULTS: The improved method could remarkably increase the cell number and reduce neuronal damnification. The primary culture was characterized by high uniformity, purity, normal synapse formation and longtime livability. CONCLUSION: This is a simple and reliable technique for the in vitro primary culture of rat cortical neurons.

[Methyl-CpG-binding protein 2 gene and CDKL5 gene mutation in patients with Rett syndrome: analysis of 177 Chinese pediatric patients].

OBJECTIVE: To study the spectrum of mutations in methyl-CpG-binding protein 2 gene (MECP2) and cyclin-dependent kinase-like 5 gene (CDKL5) in Chinese pediatric patients with Rett syndrome (RTT), and establish a simple, quick, and efficient gene test method as well as screen a strategy of genetic diagnosis for RTT. METHODS: Genomic DNA was extracted using standard procedures from the peripheral blood leukocytes of 117 pediatric patients diagnosed from 1987 to 2007. PCR was used to amplify the exons 1 - 4 of MECP2 using published primers. If no mutation was identified after screening exons 2 - 4, exon 1 was screened. If no mutation was identified in MECP2 by sequencing, multiplex ligation dependent probe amplification (MLPA) was employed to screen for large deletions by using P015C kit. If no mutation was identified in the MECP2 by sequencing and MLPA respectively, then the coding region of CDKL5 was screened by denaturing high performance liquid chromatography (DHPLC). RESULTS: The total mutation frequency in MECP2 and CDKL5 genes among all RTT patients was 82%. MECP2 mutations were found in 86% (137/159) of the patients with classical RTT and in 44% (8/18) of those with atypical RTT. Most of the mutations were missense mutations, accounting for 39%, followed in order of frequency by nonsense mutations 28%, frame shift mutations 17% and large deletions 14.5%. The eight most frequent MECP2 mutations were p.T158M (13%), p.R168X (12%), c.806delG (7%), p.R255X (6%), p.R270X (5%), p.R133C (5%), p.R306C (4%), and p.R106W (3%), with p.T158M as the most common of the MECP2 mutations and c.806delG as a hotspot mutation in Chinese patients with RTT. Only one synonymous mutation was identified in CDKL5. CONCLUSION: The spectrum of MECP2 mutations within the mainland Chinese RTT patients is similar to that of those patients reported in the world. p.T158M, p.R168X, c.806delG, p.R255X, p.R270X, p.R133C, p.R306C, and p.R106W are the hotspot mutations of MECP2 and c.806delG is a specific hotspot mutation in Chinese patients with RTT. The most effective method to screen mutations is to screen the exon 4. MLPA is an effective supplement to the routine methods.

[Multiplex ligation-dependent probe amplification analysis of subtelomeric chromosome rearrangements in children with idiopathic mental retardation].

OBJECTIVE: To study the rate of subtelomeric rearrangements in patients with idiopathic mental retardation (MR) and to search the cause of MR. METHODS: DNA was extracted and purified from peripheral blood leukocytes of 180 patients with idiopathic MR. DNA was tested using specific subtelomeric multiplex ligation-dependent probe amplification (MLPA) kits P036B/C and P070 according to manufacturer's instructions. The amplification products were separated by capillary electrophoresis using an ABI 3100 automated sequencer and size standard. MLPA data were extracted by GeneScan Analysis software. Data normalization and analysis were performed with the built-in MLPA application in GeneMarker. RESULTS: Among 180 patients with idiopathic MR, 12 had pathological subtelomeric deletions including 3 cases with a 4p deletion, 2 cases with a deletion at 9q and 22q respectively, 1 case with a deletion at 1p, 7p, 8p, 9q and 12q respectively. Subtelomeric rearrangements were responsible for 7% cases of idiopathic mental retardation. CONCLUSION: Subtelomeric rearrangement is a common cause of idiopathic mental retardation.

[A case of Leigh syndrome associated with respiratory chain complex I deficiency due to mitochondrial gene 13513G>A mutation].

Leigh syndrome is a genetically heterogeneous disease caused by defects in enzymes involved in aerobic energy metabolism and the Krebs', cycle. Mitonchondrial complex I deficiency is a main cause of Leigh syndrome. In this study, a Chinese child with Leigh syndrome caused by 13513G>A mutation was reported. The proband was the first child of his parents. The previously healthy boy presented with generalized epilepsy at 12 years of age. When he visited Peking University First Hospital at 13 years of age, he had subacute loss of vision in two eyes and temporal defect of visual field in the left eye. He walked with a spastic gait. His blood lactate and pyruvate levels were elevated. Muscle biopsy showed mild lipid accumulation in muscle fiber. An electrocardiogram showed incomplete right bundle branch block. Brain magnetic resonance imaging showed bilateral, symmetrical lesions in the basal ganglia, supporting the diagnosis of Leigh syndrome. 13513G>A mutation was identified by gene analysis in the patient, which led to mitochondrial respiratory chain complex I deficiency. Multivitamins and L-carnitine were administered. At present, the patient is 16 years old and has progressive deterioration with significant muscle weakness and body weight loss. He is absent from school. He has no obvious retardation in intelligence. 13513G>A mutation was first identified by gene analysis in Chinese population with Leigh syndrome. This may be helpful in genetic counseling.

X chromosome inactivation in Rett Syndrome and its correlations with MECP2 mutations and phenotype.

Rett syndrome (RTT) is an X-linked dominant neurodevelopment disorder, which is mainly caused by gene mutation of methyl-CpG-binding protein 2 (MECP2). The correlations between genotype, X chromosome inactivation (XCI), and phenotype have been studied, but the results are conflicting. In the present study, XCI patterns in patients and their mothers, parental origin of skewed X chromosome in patients, and the correlations between XCI, genotype, and phenotype were analyzed in 52 cases of RTT with MECP2 mutations, 50 RTT mothers, and 48 normal female controls. The results showed XCI and genotype had limitations in explaining all the phenotypic manifestations of RTT. Other genomic factors have to be considered to explain the phenotypic differences.

Proteolipid protein 1 gene mutation in nine patients with Pelizaeus-Merzbacher disease.

BACKGROUND: Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with symptoms including nystagmus, impaired motor development, ataxia, and progressive spasticity. The proteolipid protein 1 (PLP1) gene is the only pathogenic gene of PMD. Duplication of the PLP1 gene is the most frequent gene defect, accounting for 50%-70% of PMD cases, whereas point mutations in the coding sequence or the splice sites account for 10%-25% of PMD cases. This study aimed to identify PLP1 mutations in nine unrelated Chinese patients (P1-9) with PMD, and 14 subjects from the family of patient 2 were also described. METHODS: Genomic DNA was extracted from peripheral blood samples. Gene dosage was determined using the multiplex ligation-dependent probe amplification (MLPA). All 7 exons and exon-intron boundaries of the PLP1 gene were amplified and analyzed using direct DNA sequencing. RESULTS: Of these nine patients, there were four transitional, four classical, and one connatal PMD according to their clinical and radiological presentations. PLP1 duplications were identified in patients 1-7 with PMD. Their mothers were PLP1 duplications carriers as well. Both duplication carriers and normal genotypes of PLP1 were identified in the family members of patient 2. A c.517C > T (p. P173S) hemizygous missense mutation in exon 4 was found in patient 8 with PMD, and his mother was shown to be a heterozygote of this mutation. CONCLUSIONS: We identified seven genomic duplications and one missense mutation (p. P173S) of the PLP1 gene in eight Chinese patients with PMD. This is the report about PLP1 mutations in PMD patients from the mainland of China.

[Methylation-specific multiplex ligation-dependent probe amplification in diagnosis of Prader-Willi syndrome and Angelman syndrome].

OBJECTIVE: To verify the sensitivity and reliability of methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and to develop a simple, accurate, reliability method of genetic diagnosis for AS and PWS. METHODS: Peripheral blood samples were collected from 4 suspected AS patients, 2 suspected PWS patients, 2 normal persons, and 2 molecular biologically proven positive controls (1 AS patient and 1 PWS patient). DNA was extracted and purified. MS-MLPA was used to detect the methylation of the CpG dinucleotide and the copy number in the 15q-q13 region. The results of MS-MLPA were confirmed by MSP. RESULTS: Three cases with maternal deletion on 15q11-q13 region and one case with paternal uniparental disomy (UPD) or imprinting center defect in 15q11-q13 region were found in the 4 suspected AS patients. One PWS case was found to be with paternal deletion in 15q11-q13 region and the other with paternal deletion in 15q11-q13 region or UPD or imprinting center defect in 15q11-q13 region. CONCLUSION: MS-MLPA is a simple, rapid, accurate, and reliable method of genetic test.

Spinal cord demyelination associated with biotinidase deficiency in 3 Chinese patients.

Biotinidase deficiency is a treatable cause of severe neurological disorders and skin problems. Spinal cord impairment is a rare complication of this disease and is commonly unrecognized. The authors encountered 3 Chinese patients with progressive spinal cord demyelination associated with biotinidase deficiency. Case 1 exhibited fatigue, proximal muscular weakness, and hypotonic paraplegia from the age of 7 years 4 months. Demyelination of cervical and thoracic cord was evident on magnetic resonance imaging (MRI). Case 2 developed visual impairment, blepharoconjunctivitis, and optic nerve atrophy from 5 years of age, which combined with progressive hypertonic paralysis, ataxia, and alopecia from the age of 7 years. His spinal MRI T2-weighted sequence revealed an extensive hyperintense lesion involving the cervical spinal cord C(2) to C(4). Bilateral optic nerves were significantly thick. In case 3, intercurrent wheezing, tachypnea, dyspnea, and lethargy occurred from the age of 1 year. Medulla and upper cervical spine edema and demyelination were found on MRI. Markedly elevated urine organic acids and decreased blood biotinidase activities were observed in the 3 patients. Biotin supplementation led to a dramatic improvement of clinical symptoms in 3 patients. The findings indicate that biotinidase deficiency should be considered in the differential diagnosis of unexplained spinal cord demyelination because prompt diagnosis and treatment with biotin may enable an excellent recovery.

[Leigh syndrome due to pyruvate dehydrogenase E1 alpha subunit gene mutation: a complicated and difficult case study].

Leigh syndrome is a genetically heterogeneous disease caused by defects in enzymes involved in aerobic energy metabolism and the Krebs' cycle. Deficiency of pyruvate dehydrogenase complex E1 alpha subunit (PDHA1) is the common cause of Leigh syndrome. In this study, one Chinese case of PDHA1 deficiency was reported. The patient was a boy with normal mental development, retarded motor development, general weakness, hypotonia and areflexia. Muscle histopathological findings suggested axonal peripheral neuropathy. Brain magnetic resonance imaging at 5 years of age revealed bilateral putamina lesions and periventricular white matter demyelination, supporting the diagnosis of Leigh syndrome. A C214T mutation in exon 3 of the PDHA1 gene was detected. After the treatment of thiamin, coenzyme Q10, Lcarnitine and carbohydrates-restricted diet, his movement ability improved significantly. At present, the patient is 8 years old and has normal school life. PDHA1 deficiency is an X-linked inherited metabolic disease, which shares various clinical manifestations and leads to difficult diagnosis. This patient predominately presented with progressive weakness and was diagnosed by gene analysis.

Functional characterization and neuronal modeling of the effects of childhood absence epilepsy variants of CACNA1H, a T-type calcium channel.

Sequencing of the T-type Ca2+ channel gene CACNA1H revealed 12 nonsynonymous single nucleotide polymorphisms (SNPs) that were found only in childhood absence epilepsy (CAE) patients. One SNP, G773D, was found in two patients. The present study reports the finding of a third patient with this SNP, as well as analysis of their parents. Because of the role of T-channels in determining the intrinsic firing patterns of neurons involved in absence seizures, it was suggested that these SNPs might alter channel function. The goal of the present study was to test this hypothesis by introducing these polymorphisms into a human Ca(v)3.2a cDNA and then study alterations in channel behavior using whole-cell patch-clamp recording. Eleven SNPs altered some aspect of channel gating. Computer simulations predict that seven of the SNPs would increase firing of neurons, with three of them inducing oscillations at similar frequencies, as observed during absence seizures. Three SNPs were predicted to decrease firing. Some CAE-specific SNPs (e.g., G773D) coexist with SNPs also found in controls (R788C); therefore, the effect of these polymorphisms were studied. The R788C SNP altered activity in a manner that would also lead to enhanced burst firing of neurons. The G773D-R788C combination displayed different behavior than either single SNP. Therefore, common polymorphisms can alter the effect of CAE-specific SNPs, highlighting the importance of sequence background. These results suggest that CACNA1H is a susceptibility gene that contributes to the development of polygenic disorders characterized by thalamocortical dysrhythmia, such as CAE.