A Novel KCNN2 Variant in a Family with Essential Tremor Plus: Clinical Characteristics and In Silico Analysis

BACKGROUND

Essential tremor (ET) is one of the more common movement disorders. Current diagnosis is solely based on clinical findings. ET appears to be inherited in an autosomal dominant pattern. Several loci on specific chromosomes have been studied by linkage analysis, but the causes of essential tremor are still unknown in many patients. Genetic studies described the association of several genes with familial ET. However, they were found only in distinct families, suggesting that some can be private pathogenic variants.

AIM OF THE STUDY

to characterize the phenotype of an Italian family with ET and identify the genetic variant associated.

METHODS

Clinical and genetic examinations were performed. Genetic testing was done with whole-exome sequencing (WES) using the Illumina platform. Bidirectional capillary Sanger sequencing was used to investigate the presence of variant in all affected members of the family. In silico prediction of pathogenicity was used to study the effect of gene variants on protein structure.

RESULTS

The proband was a 15-year-old boy. The patient was the first of two children of a non-consanguineous couple. Family history was remarkable for tremor in the mother line. His mother suffered from bilateral upper extremity kinetic tremors (since she was 20 years old), anxiety, and depression. Other relatives referred bilateral upper extremity tremors. In the index case, WES analysis performed supposing a dominant mode of inheritance, identified a novel heterozygous missense variant in potassium calcium-activated channel subfamily N member 2 (KCNN2) (NM_021614.3: c.1145G>A, p.Gly382Asp). In the pedigree investigation, all carriers of the gene variant had ET and showed variable expressivity, the elder symptomatic relative showing cognitive impairment and hallucinations in the last decade, in addition to tremor since a young age. The amino acid residue #382 is located in a transmembrane region and in silico analysis suggested a causative role for the variant. Modelling of the mutant protein structure showed that the variant causes a clash in the protein structure. Therefore, the variant could cause a conformational change that alters the ability of the protein in the modulation of ion channels Conclusions: The KCNN2 gene variant identified could be associated with ET. The variant could modify a voltage-independent potassium channel activated by intracellular calcium.

Agomelatine: A Potential Multitarget Compound for Neurodevelopmental Disorders

Agomelatine (AGM) is one of the latest atypical antidepressants, prescribed exclusively for the treatment of depression in adults. AGM belongs to the pharmaceutical class of melatonin agonist and selective serotonin antagonist ("MASS"), as it acts both as a selective agonist of melatonin receptors MT1 and MT2, and as a selective antagonist of 5-HT2C/5-HT2B receptors. AGM is involved in the resynchronization of interrupted circadian rhythms, with beneficial effects on sleep patterns, while antagonism on serotonin receptors increases the availability of norepinephrine and dopamine in the prefrontal cortex, with an antidepressant and nootropic effect. The use of AGM in the pediatric population is limited by the scarcity of data. In addition, few studies and case reports have been published on the use of AGM in patients with attention deficit and hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Considering this evidence, the purpose of this review is to report the potential role of AGM in neurological developmental disorders. AGM would increase the expression of the cytoskeleton-associated protein (ARC) in the prefrontal cortex, with optimization of learning, long-term memory consolidation, and improved survival of neurons. Another important feature of AGM is the ability to modulate glutamatergic neurotransmission in regions associated with mood and cognition. With its synergistic activity a melatoninergic agonist and an antagonist of 5-HT2C, AGM acts as an antidepressant, psychostimulant, and promoter of neuronal plasticity, regulating cognitive symptoms, resynchronizing circadian rhythms in patients with autism, ADHD, anxiety, and depression. Given its good tolerability and good compliance, it could potentially be administered to adolescents and children.

Modafinil and orexin system: interactions and medico-legal considerations

Modafinil (Mo) is increasingly being used as an enhancement drug rather than for its therapeutic effects. The effects of this drug have been examined in attention deficit disorders, depression, mental fatigue, and in enhancing concentration. The drug possesses wakefulness-promoting properties which are mediated through the interaction of orexinergic system with the activated sympathetic nervous system. Mo exerts a synergistic effect on the orexin system, controls energy expenditure and strengthens the ability of the individual to exercise. Some view Mo as a drug that enhances sports performance, since it induces a prolonged wakefulness and decreasing the sense of fatigue. These characteristics being similar to conventional stimulants have allowed Mo to emerge as a novel stimulant requiring medico-legal considerations. However, more studies are needed to better understand the mid and long-term effects of the drug on user/abuser.

Milk nutrition and childhood epilepsy: An ex vivo study on cytokines and oxidative stress in response to milk protein fractions

We present a pilot study on the effects of milk protein fractions [α_S1-casein (CN), α_S2-CN, κ-CN, β-CN, and a mix of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG)] from different animal species (bovine, ovine, and caprine) on pro- and anti-inflammatory cytokines and oxidative status in cultured peripheral blood mononuclear cells from children with generalized epilepsy. Peripheral blood mononuclear cells (PBMC) were obtained by density gradient from blood of 10 children with generalized epilepsy (5 males; mean age 33.6 ± 5.4 mo) and 10 controls (5 males; mean age 35.6 ± 6.8 mo). Children with epilepsy were grouped according to cytokine levels as follows: children with epilepsy having low levels of cytokines not different from those of control children (LL-EC); children with epilepsy having cytokine levels at least 5-fold higher (medium levels) than those of control children (ML-EC); and children with epilepsy having cytokine levels at least 10-fold higher (high levels) than those of control children (HL-EC). The production of tumor necrosis factor-α (TNF-α), IL-10, IL-6, and IL-1β was studied in cultured PBMC incubated with α_S1-CN, α_S2-CN, κ-CN, β-CN, and a mix of α-LA and β-LG from bovine, caprine, and ovine milks. The levels of reactive oxygen and nitrogen species (ROS/RNS) and catalase activity were assessed in cultured supernatant. In the HL-EC group, β-CN from small ruminant species (ovine and caprine) induced the highest levels of TNF-α, whereas PBMC incubated with α_S2-CN from ovine milk and the mix of β-LG and α-LA from all tested milk species had the lowest levels of TNF-α. Within the HL-EC group, production of IL-1β was higher for bovine and ovine α_S2-CN fractions and lower for caprine and ovine β-CN and κ-CN. In the HL-EC group, IL-6 was higher in cultured PBMC incubated with α_S2-CN from bovine and ovine milk than from caprine milk. The cytokine IL-10 did not differ among milking species. The highest levels of ROS/RNS were found after incubation of PBMC with the β-CN fraction in bovine milk. Catalase activity was higher in PBMC cultured with β-CN isolated from bovine and caprine milk and with α_S1-CN from ovine milk.

Milk from different species: Relationship between protein fractions and inflammatory response in infants affected by generalized epilepsy

The present study was undertaken to evaluate the effect of protein fractions from bovine, caprine, and ovine milk on production of cytokines and reactive oxygen species (ROS) and reactive nitrogen species (RNS) by cultured peripheral blood mononuclear cells (PMBC) from infants with generalized epilepsy. Bovine, caprine, and ovine bulk milks were pasteurized and analyzed for chemical composition. Then, PBMC were isolated from 10 patients with generalized epilepsy (5 males; mean age 33.6±5.4mo). Production of tumor necrosis factor-α (TNF-α), IL-10, IL-6, and IL-1β was studied in cultured PBMC (from infants with epilepsy and controls) stimulated by bovine, caprine, and ovine milk and casein and whey protein fractions, and levels of ROS and RNS were measured in the culture supernatant. The ability of PBMC to secrete cytokines in response to milk and protein fraction stimulation may predict the secretion of soluble factor TNF-α in the bloodstream of challenged patients. Bovine, caprine, and ovine bulk milks induced low-level production of IL-10 by cultured PBMC in at least 50% of cases; the same behavior was observed in both casein and whey protein fractions for all species studied. Bovine and ovine milk and their casein fractions induced production of lower levels of IL-1β in 80% of patients, whereas caprine milk and its casein fraction induced the highest levels in 80% of patients. The amount of IL-6 detected after stimulation of PBMC by milk and its fractions for all species was lower than that of other proinflammatory cytokines. In the bovine, total free radicals were higher in bulk milk and lower in the casein fraction, whereas the whey protein fraction showed an intermediate level; in caprine, ROS/RNS levels were not different among milk fractions, whereas ovine had higher levels for bulk milk and casein than the whey protein fraction. Lower levels of ROS/RNS detected in PBMC cultured with caprine milk fraction could be responsible for the lower levels of TNF-α cytokine in the corresponding fraction. Cytokines might be useful biomarkers to discriminate the effects of foods on the inflammatory response; dietary strategies could help in alleviating the negative effects of epilepsy in infants.

A qualitative description of the peptide sharing between poliovirus and Homo sapiens

In a companion paper, we reported that pentapeptides from human poliovirus 1, Mahoney strain, occur repeatedly in human proteins for a total of more than 18,000 overlaps. In the present study, we describe the distribution of the polio pentapeptides throughout biochemical pathways and networks characterizing functions and tissues in the human host. The present study might be of help to better define the poliovirus-host relationships as well as for designing peptide modules with anti-polio activity.

A quantitative description of the peptide sharing between poliovirus and Homo sapiens

In the present study, we analyze the peptide commonality between poliovirus polyprotein and the human proteins. We report on the following findings: (1) the extent of polio peptide overlap on the human proteome is high, and involves the entire viral polyprotein; (2) viral peptide matching affects human proteins linked to fundamental cellular functions. The data may help to further our understanding of the relationships between poliovirus and the human host.