The continuously evolving phenotype of succinic semialdehyde dehydrogenase deficiency.

The objective of the study is to evaluate the evolving phenotype and genetic spectrum of patients with succinic semialdehyde dehydrogenase deficiency (SSADHD) in long-term follow-up. Longitudinal clinical and biochemical data of 22 pediatric and 9 adult individuals with SSADHD from the patient registry of the International Working Group on Neurotransmitter related Disorders (iNTD) were studied with in silico analyses, pathogenicity scores and molecular modeling of ALDH5A1 variants. Leading initial symptoms, with onset in infancy, were developmental delay and hypotonia. Year of birth and specific initial symptoms influenced the diagnostic delay. Clinical phenotype of 26 individuals (median 12 years, range 1.8-33.4 years) showed a diversifying course in follow-up: 77% behavioral problems, 76% coordination problems, 73% speech disorders, 58% epileptic seizures and 40% movement disorders. After ataxia, dystonia (19%), chorea (11%) and hypokinesia (15%) were the most frequent movement disorders. Involvement of the dentate nucleus in brain imaging was observed together with movement disorders or coordination problems. Short attention span (78.6%) and distractibility (71.4%) were the most frequently behavior traits mentioned by parents while impulsiveness, problems communicating wishes or needs and compulsive behavior were addressed as strongly interfering with family life. Treatment was mainly aimed to control epileptic seizures and psychiatric symptoms. Four new pathogenic variants were identified. In silico scoring system, protein activity and pathogenicity score revealed a high correlation. A genotype/phenotype correlation was not observed, even in siblings. This study presents the diversifying characteristics of disease phenotype during the disease course, highlighting movement disorders, widens the knowledge on the genotypic spectrum of SSADHD and emphasizes a reliable application of in silico approaches.

Assessment of intellectual impairment, health-related quality of life, and behavioral phenotype in patients with neurotransmitter related disorders: Data from the iNTD registry.

Inherited disorders of neurotransmitter metabolism are a group of rare diseases, which are caused by impaired synthesis, transport, or degradation of neurotransmitters or cofactors and result in various degrees of delayed or impaired psychomotor development. To assess the effect of neurotransmitter deficiencies on intelligence, quality of life, and behavior, the data of 148 patients in the registry of the International Working Group on Neurotransmitter Related Disorders (iNTD) was evaluated using results from standardized age-adjusted tests and questionnaires. Patients with a primary disorder of monoamine metabolism had lower IQ scores (mean IQ 58, range 40-100) within the range of cognitive impairment (<70) compared to patients with a BH4 deficiency (mean IQ 84, range 40-129). Short attention span and distractibility were most frequently mentioned by parents, while patients reported most frequently anxiety and distractibility when asked for behavioral traits. In individuals with succinic semialdehyde dehydrogenase deficiency, self-stimulatory behaviors were commonly reported by parents, whereas in patients with dopamine transporter deficiency, DNAJC12 deficiency, and monoamine oxidase A deficiency, self-injurious or mutilating behaviors have commonly been observed. Phobic fears were increased in patients with 6-pyruvoyltetrahydropterin synthase deficiency, while individuals with sepiapterin reductase deficiency frequently experienced communication and sleep difficulties. Patients with BH4 deficiencies achieved significantly higher quality of life as compared to other groups. This analysis of the iNTD registry data highlights: (a) difference in IQ and subdomains of quality of life between BH4 deficiencies and primary neurotransmitter-related disorders and (b) previously underreported behavioral traits.

Genetics of Lafora progressive myoclonic epilepsy: current perspectives.

Lafora disease (LD) is a fatal neurodegenerative disorder caused by loss-of-function mutations in either laforin glycogen phosphatase gene (EPM2A) or malin E3 ubiquitin ligase gene (NHLRC1). LD is associated with gradual accumulation of Lafora bodies (LBs). LBs are aggregates of polyglucosan, a long, linear, poorly branched, hyperphosphorylated, insoluble form of glycogen. Loss-of-function mutations either in the EPM2A or in the NHLRC1 gene lead to polyglucosan formation. One hypothesis on LB formation is based on findings that laforin-malin complex downregulates glycogen synthase (GS) through malin-mediated ubiquitination, and the other one is based on findings that laforin dephosphorylates glycogen. According to the first hypothesis, polyglucosan formation is a result of increased GS activity, and according to the second, an increased glycogen phosphate leads to glycogen conformational change, unfolding, precipitation, and conversion to polyglucosan, while GS remains bound to the precipitating glycogen. In this review, we summarize all the recent findings that have important implications for the treatment of LD, all of them showing that partial inhibition of GS activity may be sufficient to prevent the progression of the disease. The current perspective in LD is high-throughput screening for small molecules that act on the disease pathway, that is, partial inhibitors of GS, which opens a therapeutic window for potential treatment of this fatal disease.

Quantitation of pregabalin in dried blood spots and dried plasma spots by validated LC-MS/MS methods.

In this paper, novel LC-MS/MS methods for the determination of antiepileptic drug pregabalin in dried matrix spots (DMS) are presented. This attractive technique of sample collection in micro amount was utilized in the form of dried blood spots (DBS) and dried plasma spots (DPS). Following a pre-column derivatization procedure, using n-propyl chloroformate in the presence of n-propanol, and consecutive liquid-liquid extraction, derivatized pregabalin and its internal standard, 4-aminocyclohexanecarboxylic acid, were detected in positive ion mode by applying two SRM transitions per analyte. A YMC-Pack Octyl column (50mm×4.0mm, 3µm particle size) maintained at 30°C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550µL/min and total run time 2min. Established methods were fully validated over the concentration range of 0.200-20.0µg/mL for DBS and 0.400-40.0µg/mL for DPS, respectively, while specificity, accuracy, precision, recovery, matrix-effect, stability, dilution integrity and spot homogeneity were found within acceptance criteria. Validated methods were applied for the determination of pregabalin levels in dried blood and plasma samples obtained from patients with epilepsy, after per os administration of commercial capsules. Comparison of drug level in blood and plasma, as well as correction steps undertaken in order to overcome hematocrit issue, when analyzing DBS, are also given.

Vigabatrin in dried plasma spots: validation of a novel LC-MS/MS method and application to clinical practice.

This paper presents a LC-MS/MS method for the determination of antiepileptic drug vigabatrin in dried plasma spots (DPS). Due to its zwitterionic chemical structure, a pre-column derivatization procedure was performed, aiming to yield enhanced ionization efficiency and improved chromatographic behaviour. Propyl chloroformate, in the presence of propanol, was selected as the best derivatization reagent, providing a strong signal along with reasonable run time. A relatively novel sample collection technique, DPS, was utilized, offering easy sample handling and analysis, using a sample in micro amount (∼5µL). Derivatized vigabatrin and its internal standard, 4-aminocyclohexanecarboxylic acid, were extracted by liquid-liquid extraction (LLE) and determined in positive ion mode by applying two SRM transitions per analyte. A Zorbax Eclipse XDB-C8 column (150×4.6mm, 5µm particle size) maintained at 30°C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550µL/min and total run time 4.5min. The assay exhibited excellent linearity over the concentration range of 0.500-50.0µg/mL, which is suitable for the determination of vigabatrin level after per os administration in children and youths with epilepsy, who were on vigabatrin therapy, with or without co-medication. Specificity, accuracy, precision, recovery, matrix-effect and stability were also estimated and assessed within acceptance criteria.

Lafora disease: severe phenotype associated with homozygous deletion of the NHLRC1 gene.

Lafora disease (LD) is a severe, autosomal recessive, latechildhood- to teenage-onset, progressive myoclonic epilepsy. It is due to either EPM2A or NHLRC1 mutations. We describe a patient with homozygous deletion encompassing the entire NHLRC1 gene, not previously reported, and with clinical course more progressive than in the most patients with NHLRC1 mutations. The diagnosis of LD in our patient was based on the typical clinic, neurophysiological presentation, as well as skin biopsy followed by molecular genetics findings. She developed normally until the age of 15, when she had her first occipital and generalized seizures. Four years after the first seizure the patient became bedridden, demented and presented with severe clinical condition. She died of pneumonia at age 20. This report is the first case of homozygosity for NHLRC1 deletion and thus adds to mutational heterogeneity of LD. Besides, it widens the spectrum of LD patients with severe phenotype and NHLRC1 mutations.

Clubfoot in children.

Clubfoot, or talipes equinovarus, is a deformity consisting of equinus, varus, and adductus foot deformity. The true etiology of congenital clubfoot is unknown; several theories have been proposed. The pathology of the individual bones contributes to the clubfoot deformity and soft tissue contractures around the ankle and talocalcaneonavicular joint maintains the deformity and involve muscles, tendons, tendon sheaths, ligaments and joint capsules. Various treatment regimens have been proposed, including the use of corrective splinting, taping, and casting. Surgery in clubfoot is indicated for deformities that do not respond to conservative treatment by serial manipulation and casting. Surgery in the treatment of clubfoot must be tailored to the age of the child and to the deformity to be corrected. The main goals of treatment is the painless, functional and anatomical normal foot without need for custom made footwear, and those can be achieved after detailed, indivudial approach with great experience in pediatric orthopedics.