Megaconial congenital muscular dystrophy: Same novel homozygous mutation in CHKB gene in two unrelated Chinese patients.

Megaconial congenital muscular dystrophy (CMD) is a rare form of congenital muscular dystrophy attributed to an autosomal recessive CHKB mutation. We report two unrelated Chinese girls with Megaconial CMD who harbored the same novel homozygous CHKB mutation but exhibited different phenotypes. Patient 1, who is now 8 years old, has autism, intellectual disabilities, mild girdle weakness, and characteristic muscle biopsy with COX-negative fibers. Patient 2, now 12 years old, has limited intelligence and marked weakness, with scoliosis, hip subluxation and early loss of ambulation. Both exhibited mildly elevated creatine kinase levels, have relative sparing of adductor longus and extensor digitorum longus on MRI leg muscles, and a c.598del (p.Gln200Argfs*11) homozygous CHKB loss-of-function mutation. Their parents are heterozygous carriers. This is the first report of Megaconial CMD in Chinese patients demonstrating the pathogenicity of the identified homozygous CHKB variant. A case review of all previously reported patients of different ethnicities is also included.

NDUFA9 point mutations cause a variable mitochondrial complex I assembly defect.

Mitochondrial respiratory chain complex I consists of 44 different subunits and contains 3 functional modules: the Q-, the N- and the P-module. NDUFA9 is a Q-module subunit required for complex I assembly or stability. However, its role in complex I biogenesis has not been studied in patient fibroblasts. So far, a single patient carrying an NDUFA9 variant with a severe neonatally fatal phenotype has been reported. Via exome sequencing, we identified a novel homozygous NDUFA9 missense variant in another patient with a milder phenotype including childhood-onset progressive generalized dystonia and axonal peripheral neuropathy. We performed complex I assembly analysis using primary skin fibroblasts of both patients. Reduced complex I abundance and an accumulation of Q-module subassemblies were present in both patients but more pronounced in the severe clinical phenotype patient. The latter displayed additional accumulation of P-module subassemblies, which was not present in the milder-phenotype patient. Lentiviral complementation of both patient fibroblast cell lines with wild-type NDUFA9 rescued complex I deficiency and the assembly defects. Our report further characterizes the phenotypic spectrum of NDUFA9 deficiency and demonstrates that the severity of the clinical phenotype correlates with the severity of the effects of the different NDUFA9 variants on complex I assembly.

MALDI-MS profiling of serum O-glycosylation and N-glycosylation in COG5-CDG.

Congenital disorders of glycosylation (CDG) are due to defective glycosylation of glycoconjugates. Conserved oligomeric Golgi (COG)-CDG are genetic diseases due to defects of the COG complex subunits 1-8 causing N-glycan and O-glycan processing abnormalities. In COG-CDG, isoelectric focusing separation of undersialylated glycoforms of serum transferrin and apolipoprotein C-III (apoC-III) allows to detect N-glycosylation and O-glycosylation defects, respectively. COG5-CDG (COG5 subunit deficiency) is a multisystem disease with dysmorphic features, intellectual disability of variable degree, seizures, acquired microcephaly, sensory defects and autistic behavior. We applied matrix-assisted laser desorption/ionization-MS for a high-throughput screening of differential serum O-glycoform and N-glycoform in five patients with COG5-CDG. When compared with age-matched controls, COG5-CDG showed a significant increase of apoC-III0a (aglycosylated glycoform), whereas apoC-III1 (mono-sialylated glycoform) decreased significantly. Serum N-glycome of COG5-CDG patients was characterized by the relative abundance of undersialylated and undergalactosylated biantennary and triantennary glycans as well as slight increase of high-mannose structures and hybrid glycans. Using advanced and well-established MS-based approaches, the present findings reveal novel aspects on O-glycan and N-glycan profiling in COG5-CDG patients, thus providing an increase of current knowledge on glycosylation defects caused by impairment of COG subunits, in support of clinical diagnosis. Copyright © 2017 John Wiley & Sons, Ltd.

SCN2A mutation in a Chinese boy with infantile spasm - response to Modified Atkins Diet.

BACKGROUND: Mutation of SCN2A, encoding for voltage-gated sodium channel type II alpha subunit, has been demonstrated in various epilepsy phenotypes, ranging from benign to severe epileptic disorders and recently this had been reported for cases with infantile spasm (IS). METHODS: We study a 6 years-old Chinese boy with severe developmental delay who had infantile spasm since 15 months. He later had severe intellectual disability and autistic features. He failed to respond to most anticonvulsants. Modified Atkins Diet was introduced at 4 years of age and he showed a seizure remission for 12 months with only 1 anticonvulsants. To clarify the unknown etiology, mutations were screened for genes associated with brain development or synaptic function. RESULTS: A heterozygous mutation (c.3631G>A; p.E1211K) was identified in exon 21 of SCN2A gene. This mutation has been reported previously only in a Japanese patient with IS. CONCLUSION: This is the first case of SCN2A mutation identified in Chinese. Similarity of our case and one Japanese case of infantile spasm indicated that this E1211K mutation is important as possible etiology of IS. Trial of Modified Atkins Diet for other cases of infantile spasm with similar SCN2A mutations is worthwhile pursuing.

Lathosterolosis: a disorder of cholesterol biosynthesis resembling smith-lemli-opitz syndrome.

Lathosterolosis is an inborn error of cholesterol biosynthesis due to deficiency of the enzyme 3-beta-hydroxysteroid-delta-5-desaturase (or sterol-C5-desaturase or SC5D). This leads to a block in conversion of lathosterol into 7-dehydrocholesterol. Only three patients with lathosterolosis have been reported in literature, of which one survived. We report a patient with dysmorphism, multiple congenital anomalies, and developmental delay, initially suspected to have Smith-Lemli-Opitz syndrome, who was later found to have elevated levels of lathosterol in both plasma and fibroblasts. Genetic study confirmed a compound heterozygous mutation in the sterol-C5-desaturase-like (SC5DL) gene on chromosome 11q23. Simvastatin was started as a treatment therapy and it resulted in normalization of blood lathosterol level and improvement in the neurodevelopmental profile. However, additional patients are needed for better delineation of the clinical spectrum, genotype-phenotype correlation, and potential efficacy of simvastatin treatment in this rare disorder. If the presence of distinctive facial features and limb anomalies raise the suspicion of a cholesterol biosynthesis defect, testing of full sterol profile is warranted as normal cholesterol or 7-dehydrocholesterol levels cannot rule out the diagnosis of cholesterol synthesis defect like lathosterolosis.

COG5-CDG with a Mild Neurohepatic Presentation.

The conserved oligomeric Golgi (COG) complex is an eight subunit protein involved in the retrograde transport of Golgi components. It affects the localization of several Golgi glycosyltransferases and hence is involved in N- and O-glycosylation. Genetic defects in this complex belong to the rapidly expanding family of congenital disorders of glycosylation (CDG). Patients have been reported with defects of subunit 1 (CDG1-CDG), subunit 4 (CDG4-CDG), subunit 5 (CDG5-CDG), subunit 6 (CDG6-CDG), subunit 7 (CDG7-CDG), and subunit 8 (CDG8-CDG). This paper is on the second reported patient with COG5-CDG. She showed a mild neurohepatic disease with central as well as peripheral neurological involvement while in the first reported patient (with a different mutation) only mild central neurological involvement was reported.

Biochemical and molecular characterization of tyrosine hydroxylase deficiency in Hong Kong Chinese.

Tyrosine hydroxylase deficiency is a rare neurotransmitter disorder affecting the rate-limiting step in catecholamine biosynthesis. There are about 40 cases reported worldwide. Here, we report the biochemical and molecular findings of eight unrelated Chinese patients with tyrosine hydroxylase deficiency. We have identified eight novel mutations with 5 missense, 2 nonsense and 1 splicing mutations in the TH gene, namely p.R153X, p.R169X, p.G294R, p.G315S, p.A385V, p.I394T, p.G408R, and c.1163+5G>C. The mutations of the TH gene in Chinese are heterogeneous.

Health-related quality of life of children with epilepsy in Hong Kong: how does it compare with that of youth with epilepsy in Canada?

OBJECTIVE: The primary aim of our study was to compare the health-related quality of life (HRQL) of children with epilepsy in Hong Kong with that of children with epilepsy in Canada, and to explore possible factors affecting these findings. A second interest was to determine agreement between proxy reports and self-ratings among children with epilepsy in Hong Kong, compare these with findings in Canada, and identify factors that influence the concordance. METHODS: Child self-report and parent-proxy questionnaires on an epilepsy-specific HRQL measure, appropriately translated and validated in Chinese, were administered to 266 Hong Kong children and their parents. An unpaired t test was used to compare the scores with published results from 381 Canadian children and their parents, who used the original English version of the measure. Demographic characteristics of the two groups were compared using t tests, chi2 tests, and Fisher's exact tests. Agreement between parents' and children's scores was evaluated with intraclass correlation coefficients (ICCs) and standardized response means (SRMs). The total HRQL score differences between parents and children in Hong Kong were compared with those in Canada using an unpaired t test. Factors that might affect the parent-child score difference were studied using Pearson correlation analysis, chi2 test, and analysis of variance. Factors studied included: sex, current age, age at diagnosis, duration of epilepsy, number of antiepileptic drugs used, type of seizure, seizure severity, cognition of the child, the type of school attended, presence of neurological problems, presence of behavioral problems, recent health care usage, education and employment status of both parents, housing status of the family, and relationship of the proxy respondent to the child. RESULTS: (1) In contrast to the Canadian sample, Hong Kong children with epilepsy were older (P<0.01), had a longer duration of epilepsy (P<0.01) and less severe seizures (P<0.01), and were more likely to attend normal schools (P<0.01). Children in Hong Kong reported more interpersonal/social difficulties (P<0.01), more worries (P<0.01), and more secrecy about their epilepsy (P<0.01). Parents in Hong Kong believed that their children perceived more worries (P<0.01) and were more secretive about their epilepsy (P<0.01). (2) Moderate to good agreement between parent-proxy response scores and child self-report scores was demonstrated (ICC=0.50-0.69, SRM=0.19-0.33). The total HRQL score differences between parent and child in Hong Kong were not different from those in Canada. None of the factors studied were related to the parent-child score difference. CONCLUSIONS: Youth with epilepsy in Hong Kong and their parents reported poorer quality of life than children with epilepsy in Canada. Further studies are necessary to identify the determinants of HRQL in children with epilepsy in different cultures. Acceptable agreement between the two ratings suggests that proxy reports can be used when child self-reports cannot be obtained.

Moyamoya syndrome in a child with Down syndrome.

Moyamoya syndrome has been reported in association with Down syndrome. In paediatric patients, the usual presentation is that of ischaemic stroke. We report a 9-year-old boy with Down syndrome and moyamoya syndrome who presented with acute-onset left hemiparesis. This is the first such reported case in Hong Kong. There is growing evidence that the chromosomal abnormalities in patients with Down syndrome may contribute to a vulnerability for the development of moyamoya syndrome. A high index of suspicion is necessary to make the correct diagnosis. Medical and surgical management strategies for this disease are discussed. Surgical intervention should proceed without delay, if indicated, to prevent further neurological deterioration. A multidisciplinary approach is recommended for the rehabilitation of these patients.