Macromolecular-Suppressed GABA-Edited MR Spectroscopy in the Posterior Cingulate Cortex of Patients With Acute Mild Traumatic Brain Injury.

BACKGROUND: Mild traumatic brain injury (mTBI) causes a number of molecular and cellular alterations. There is evidence of an imbalance between the main excitatory (glutamate, Glu) and the main inhibitory (gamma-aminobutyric acid [GABA]) neurotransmitters following mTBI. In vivo human GABA-Glu balance studies following mTBI are sparse. PURPOSE: To investigate the effect of acute mTBI on the GABA concentration measured in the posterior cingulate cortex (PCC) of pediatric patients by using the macromolecular (MM)-suppressed GABA J-editing technique. STUDY TYPE: Prospective patient and phantom. PARTICIPANTS: A total of 14 pediatric patients (mean age 16.0 ± 1.7) with acute mTBI (<3 days after trauma; Glasgow Coma Scale 15) and 16 healthy volunteers (mean age 16.9 ± 2.8). Phantom: 524 cm3 sphere containing 10 mM glycine, 10 mM GABA. FIELD STRENGTH/SEQUENCE: A 3 T, MEGA-PRESS pulse sequence. ASSESSMENT: GABA spectra were processed in Gannet software. MM-suppressed GABA editing efficiency was derived from the phantom study. Absolute GABA and glutamate + glutamine (Glx) concentrations were quantified using different types of correction and compared between groups. N-acetyl aspartate (NAA) and choline (Cho) levels relative to tCr were also compared. STATISTICAL TESTS: Shapiro-Wilk test, Mann-Whitney U test, Student t-test, Pearson or Spearman correlations. P < 0.01 was considered statistically significant. RESULTS: The MM-suppressed GABA editing efficiency was 0.63. GABA signal fit error was <16% for all participants. The GABA concentration in the PCC of the mTBI group was significantly different from that in healthy controls: GABA/tCr was higher by 27%, absolute GABA concentration with different types of correction was higher by ≈17%. No significant differences were observed in Glx concentrations (P ≥ 0.32) or in Glx/tCr (P ≥ 0.1), NAA/tCr (P = 0.55), and Cho/tCr levels (P = 0.85). DATA CONCLUSION: We report an increase in the GABA concentration in the PCC region in acute mTBI pediatric patients. This may suggest activation of GABA synthesis and impairment of the GABAergic system after acute mTBI. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 1.

A Clinical Case of a Homozygous Deletion in the APOA5 Gene with Severe Hypertriglyceridemia.

Background: Hypertriglyceridemia (HTG) is one of the most common forms of lipid metabolism disorders. The leading clinical manifestations are pancreatitis, atherosclerotic vascular lesions, and the formation of eruptive xanthomas. The most severe type of HTG is primary (or hereditary) hypertriglyceridemia, linked to pathogenic genetic variants in LPL, APOC2, LMF1, and APOA5 genes. Case: We present a clinical case of severe primary hypertriglyceridemia (TG level > 55 mmol/L in a 4-year-old boy) in a consanguineous family. The disease developed due to a previously undescribed homozygous deletion in the APOA5 gene (NM_052968: c.579_592delATACGCCGAGAGCC p.Tyr194Gly*68). We also evaluate the clinical significance of a genetic variant in the LPL gene (NM_000237.2: c.106G>A (rs1801177) p.Asp36Asn), which was previously described as a polymorphism. In one family, we also present a different clinical significance even in heterozygous carriers: from hypertriglyceridemia to normotriglyceridemia. We provide evidence that this heterogeneity has developed due to polymorphism in the LPL gene, which plays the role of an additional trigger. Conclusions: The homozygous deletion of the APOA5 gene is responsible for the severe hypertriglyceridemia, and another SNP in the LPL gene worsens the course of the disease.

A novel mutation in the PEX26 gene in a family from Dagestan with members affected by Zellweger spectrum disorder.

BACKGROUND: Peroxisome biogenesis disorders (PBD) are a heterogeneous group of autosomal recessive disorders that affect multiple organ systems. Approximately 80% of PBD patients are classifiedin the Zellweger syndrome spectrum, which is generally caused by mutations in the PEX1, PEX6, PEX10, PEX12, or PEX26 genes. METHODS: We present the clinical characteristics of three male members with cholestatic hepatopathy and developmental delay. Next-Generation Sequencing (NGS) was used to analyze 52 genes responsible for hereditary diseases with cholestasis. The variant was confirmed by Sanger sequencing. Dried blood spot (DBS) samples of 537 newborns from Dagestan were tested for the presence of that mutation. The frequency of the mutant allele in the population of Dagestan wasestimated using the Hardy-Weinberg equilibrium. RESULTS: Symptoms of disease manifested from the first months of life as severe hepatic dysfunction and developmental delay. Physical examination showed jaundice, hepatosplenomegaly, coagulopathy, and normal or slightly elevated level of gamma-glutamyltransferase (GGT), similar to progressive familial intrahepatic cholestasis. The level of C26 and ratio of C26/C22 in plasma were increased. A nucleotide variant in the PEX26 gene was identified: NM_017929.6:c.347 T>A, p.(Leu116Gln) in a homozygous state. Parents and healthy siblings were heterozygous for the mutant allele. This variant was not described in the Database of Single Nucleotide Polymorphism (dbSNP), it is not registered in the Human Gene Mutation Database (HGMD) v. 2020.1. The frequency of the mutant allele in the population of Dagestan is estimated to be less than 0.000931 (99% CI, 0.000929-0.000934). CONCLUSIONS: Our clinical cases from Dagestan describe the phenotype associated with the c.347 T>A,p.(Leu116Gln), variant in the PEX26 gene. We show that the onset of the clinical picture in patients with Zellweger syndrome spectrum could start with severe hepatic dysfunction and cholestasis. We suggest that biochemical screening of PBD in infants with cholestasis is necessary.

Mutation in PHACTR1 associated with multifocal epilepsy with infantile spasms and hypsarrhythmia.

A young boy with multifocal epilepsy with infantile spasms and hypsarrhythmia with minimal organic lesions of brain structures underwent DNA diagnosis using whole-exome sequencing. A heterozygous amino-acid substitution p.L519R in a PHACTR1 gene was identified. PHACTR1 belongs to a protein family of G-actin binding protein phosphatase 1 (PP1) cofactors and was not previously associated with a human disease. The missense single nucleotide variant in the proband was shown to occur de novo in the paternal allele. The mutation was shown in vitro to reduce the affinity of PHACTR1 for G-actin, and to increase its propensity to form complexes with the catalytic subunit of PP1. These properties are associated with altered subcellular localization of PHACTR1 and increased ability to induce cytoskeletal rearrangements. Although the molecular role of the PHACTR1 in neuronal excitability and differentiation remains to be defined, PHACTR1 has been previously shown to be involved in Slack channelopathy pathogenesis, consistent with our findings. We conclude that this activating mutation in PHACTR1 causes a severe type of sporadic multifocal epilepsy in the patient.

Identification of novel variants in the LDLR gene in Russian patients with familial hypercholesterolemia using targeted sequencing.

Familial hypercholesterolemia (FH) is caused by mutations in various genes, including the LDLR, APOB and PSCK9 genes; however, the spectrum of these mutations in Russian individuals has not been fully investigated. In the present study, mutation screening was performed on the LDLR gene and other FH-associated genes in patients with definite or possible FH, using next-generation sequencing. In total, 59 unrelated patients were recruited and sorted into two separate groups depending on their age: Adult (n=31; median age, 49; age range, 23-70) and children/adolescent (n=28; median age, 11; age range, 2-21). FH-associated variants were identified in 18 adults and 25 children, demonstrating mutation detection rates of 58 and 89% for the adult and children/adolescent groups, respectively. In the adult group, 13 patients had FH-associated mutations in the LDLR gene, including two novel variants [NM_000527.4: c.433_434dupG p.(Val145Glyfs*35) and c.1186G>C p.(Gly396Arg)], 3 patients had APOB mutations and two had ABCG5/G8 mutations. In the children/adolescent group, 21 patients had FH-causing mutations in the LDLR gene, including five novel variants [NM_000527.4: c.325T>G p.(Cys109Gly), c.401G>C p.(Cys134Ser), c.616A>C p.(Ser206Arg), c.1684_1691delTGGCCCAA p.(Pro563Hisfs*14) and c.940+1_c.940+4delGTGA], and 2 patients had APOB mutations, as well as ABCG8 and LIPA mutations, being found in different patients. The present study reported seven novel LDLR variants considered to be pathogenic or likely pathogenic. Among them, four missense variants were located in the coding regions, which corresponded to functional protein domains, and two frameshifts were identified that produced truncated proteins. These variants were observed only once in different patients, whereas a splicing variant in intron 6 (c.940+1_c.940+4delGTGA) was detected in four unrelated individuals. Previously reported variants in the LDLR, APOB, ABCG5/8 and LIPA genes were observed in 33 patients. The LDLR p.(Gly592Glu) variant was detected in 6 patients, representing 10% of the FH cases reported in the present study, thus it may be a major variant present in the Russian population. In conclusion, the present study identified seven novel variants of the LDLR gene and broadens the spectrum of mutations in FH-related genes in the Russian Federation.

Dicholine salt of succinic acid, a neuronal insulin sensitizer, ameliorates cognitive deficits in rodent models of normal aging, chronic cerebral hypoperfusion, and beta-amyloid peptide-(25-35)-induced amnesia.

BACKGROUND: Accumulated evidence suggests that insulin resistance and impairments in cerebral insulin receptor signaling may contribute to age-related cognitive deficits and Alzheimer's disease. The enhancement of insulin receptor signaling is, therefore, a promising strategy for the treatment of age-related cognitive disorders. The mitochondrial respiratory chain, being involved in insulin-stimulated H2O2 production, has been identified recently as a potential target for the enhancement of insulin signaling. The aim of the present study is to examine: (1) whether a specific respiratory substrate, dicholine salt of succinic acid (CS), can enhance insulin-stimulated insulin receptor autophosphorylation in neurons, and (2) whether CS can ameliorate cognitive deficits of various origins in animal models. RESULTS: In a primary culture of cerebellar granule neurons, CS significantly enhanced insulin-stimulated insulin receptor autophosphorylation. In animal models, CS significantly ameliorated cognitive deficits, when administered intraperitoneally for 7 days. In 16-month-old middle-aged C57Bl/6 mice (a model of normal aging), CS enhanced spatial learning in the Morris water maze, spontaneous locomotor activity, passive avoidance performance, and increased brain N-acetylaspartate/creatine levels, as compared to the age-matched control (saline). In rats with chronic cerebral hypoperfusion, CS enhanced spatial learning, passive avoidance performance, and increased brain N-acetylaspartate/creatine levels, as compared to control rats (saline). In rats with beta-amyloid peptide-(25-35)-induced amnesia, CS enhanced passive avoidance performance and increased activity of brain choline acetyltransferase, as compared to control rats (saline). In all used models, CS effects lasted beyond the seven-day treatment period and were found to be significant about two weeks following the treatment. CONCLUSION: The results of the present study suggest that dicholine salt of succinic acid, a novel neuronal insulin sensitizer, ameliorates cognitive deficits and neuronal dysfunctions in animal models relevant to age-related cognitive impairments, vascular dementia, and Alzheimer's disease.