Миотония и миотонические разряды при дистрофической миотонии 1-го типа с ранним дебютом: обзор литературы и описание серии случаев

Background. Dystrophic myotonia type 1 (DM1) is the most common muscular dystrophy in patients of any age. Myotonia “delayed relaxation of muscle” is the leading symptom in DM1 and can occur at any time after onset disease. Myotonia symptoms and electrical myotonia registration are delayed after onset in patients with congenital and infantile forms of DM1. This makes it difficult to diagnose and prevent fatal complications in these patients in a timely manner. Objective: presentation of the clinical data and results of needle electromyography in patients with DM1 onset in the first decade of the life; determination of the first symptoms of the disease, to estimate the age of myotonia and electrical myotonia manifestation for the optimization of the timely diagnostics of the disease.Materials and methods. 13 patients with DM1 aged from 2 months to 34 years were described. 10 patients underwent needle electromyography with analysis of spontaneous activity and needle EMG pattern. The diagnosis was made on the basis of clinical and paraclinical manifestations of the disease and identification of an increase in CTG repeats (>50) in the DMPK gene.Results. The onset with extramuscular signs of respiratory and/or feeding disturbances, dysarthria, school learning disorders, autism spectrum disturbance and “floppy infant syndrome” was noted as the first symptoms of the disease. Clinical myotonia symptoms and electrical manifestations of myotonia were absent in all patients for a long time after the disease onset. DM1 was confirmed in all mothers, however in 5 cases the onset of the disease was later than the first symptoms in patients with congenital and childhood onset forms of DM1.Conclusion. The first symptoms of the congenital and infantile forms of DM1 are not specific and occur in a wide range of diseases. Such discriminating signs of DM1 as clinical myotonia, distal muscle atrophy and electrical myotonia appear much later than the onset disease. In the group of patients before and after the formation of phrasal speech, the presented combinations of symptoms allow diagnostics of the congenital and infantile forms of DM1 at the onset of the disease. In its turn, it allows genetic counseling in burdened families and timely prevention of fatal complications.Введение. Дистрофическая миотония 1‑го типа (ДМ1) – самая частая по распространенности среди мышечных дистрофий любого возраста. Миотония в виде задержки расслабления скелетной мускулатуры при произвольных движениях является ведущим симптомом при ДМ1. Симптомы миотонии и регистрация электрической миотонии отсрочены после дебюта у пациентов с врожденной/детской формой ДМ1, что затрудняет использование их в своевременной диагностике и проведение профилактики летальных осложнений у пациентов с ранним дебютом.Цель исследования – представить клинические данные и результаты игольчатой электромиографии больных с дебютом ДМ1 на 1‑м десятилетии жизни, определить первые симптомы заболевания и возраст появления миотонии и электрической миотонии для оптимизации своевременной диагностики заболевания.Материалы и методы. Приведено описание 13 больных с ДМ1 в возрасте от 2 мес до 34 лет. 10 больным проведена игольчатая электромиография с анализом спонтанной активности и паттерна поражения скелетных мышц. Диагноз подтверждался на основании клинико‑параклинических проявлений заболевания и увеличения CTG‑повторов >50 в гене DMPK.Результаты. Дебют с внемышечной симптоматики в виде нарушения дыхания и/или кормления, дизартрии, нарушения обучения в школе, признаков расстройства аутистического спектра и нозологически неспецифического симптомокомплекса «вялого ребенка» отмечен как первые симптомы заболевания. У всех больных клинические симптомы миотонии и электрические проявления миотонии при игольчатой электромиографии появлялись значительно позже после дебюта. У всех матерей подтверждена классическая форма ДМ1, у одной – ювенильная, однако у 5 женщин заболевание дебютировало позже, чем появились первые симптомы при врожденной или детской форме ДМ1 у их детей.Выводы. Первые симптомы при врожденной и детской форме ДМ1 неспецифичны и встречаются при широком спектре заболеваний, а дискриминирующие признаки ДМ1 в виде клинической миотонии, атрофии дистальных мышц и электрической миотонии появляются много позже дебюта. В группе больных до и после формирования фразовой речи представленные комбинации симптомов позволяют диагностировать врожденную и детскую форму ДМ1 в дебюте заболевания и проводить медико‑генетическое консультирование в семьях с отягощенным анамнезом и своевременную профилактику летальных осложнений

Performance of the NA62 trigger system

The NA62 experiment at CERN targets the measurement of the ultra-rare K+ ->pi+ nu nu decay, and carries out a broad physics programme that includes probes for symmetry violations and searches for exotic particles. Data were collected in 2016–2018 using a multi-level trigger system, which is described highlighting performance studies based on 2018 data

Externalities and the nucleolus

In most economic applications, externalities prevail: the worth of a coalition depends on how the other players are organized. We show that there is a unique natural way of extending the nucleolus from (coalitional) games without externalities to games with externalities. This is in contrast to the Shapley value and the core for which many different extensions have been proposed

Search for π⁰ decays to invisible particles

The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson

Measurement of the very rare K + → π+νν¯ decay

The NA62 experiment reports the branching ratio measurement BR(K+→π+νν¯)=(10.6−3.4+4.0|stat±0.9syst)×10−11 at 68% CL, based on the observation of 20 signal candidates with an expected background of 7.0 events from the total data sample collected at the CERN SPS during 2016–2018. This provides evidence for the very rare K+→π+νν¯ decay, observed with a significance of 3.4σ. The experiment achieves a single event sensitivity of (0.839 ± 0.054) × 10−11, corresponding to 10.0 events assuming the Standard Model branching ratio of (8.4 ± 1.0) × 10−11. This measurement is also used to set limits on BR(K+→ π+X), where X is a scalar or pseudo-scalar particle. Details are given of the analysis of the 2018 data sample, which corresponds to about 80% of the total data sample

Physics beyond the standard model with kaons at NA62

The NA62 experiment at CERN Super Proton Synchrotron was designed to measure BR(K+ \u2192 \u3c0+\u3bdv\u304) with an in-fight technique, never used before for this measurement. This decay is characterised by a very precise prediction in the Standard Model. Its branching ratio, which is expected to be less than 10-10, is one of the best candidates to indicate indirect effects of new physics beyond SM at the highest mass scales. NA62 result on K+ \u2192 \u3c0+\u3bdv\u304 from the full 2016 data set is described. Also a search for an invisible dark photon A\u2032 has been performed, exploiting the efficient photon-veto capability and high resolution tracking of the NA62. The signal stems from the chain K+ \u2192 \u3c0+\u3c00 followed by \u3c00 \u2192 A\u2032\u3b3. No significant statistical excess has been identified. Upper limits on the dark photon coupling to the ordinary photon as a function of the dark photon mass have been set, improving on the previous limits over the mass range 60 - 110 MeV/c2

Recent results in kaon physics

A review of the present experimental status of the K → πνν (Kπνν) and other kaon decay analyses at experiments NA62 (CERN) and KOTO (J-PARC) is given. The Kπνν decay is one of the best candidates among the rare meson decays for indirect searches for new physics in the mass ranges complementary to those accessible by current accelerators. The Standard Model (SM) prediction of the branching fraction (B) of the Kπνν decay is lower than 10−10 in both neutral and charged modes. The NA62 experiment aims to measure the B of the charged mode with better than 10% precision. Three candidate events, compatible with the SM prediction, have been observed from a sample of 2.12×1012 K+ decays collected in 2016 and 2017 by NA62. More than twice the statistics is available in the 2018 dataset currently being analysed. The KOTO experiment in Japan aims to measure B(KL → π0νν) using a technique similar to NA62, but with much lower momentum. In the first dataset taken in 2015 zero signal candidate events were observed. The current status of the analysis of the 2016-2018 dataset with 1.4 times more data is presented. Finally, the most recent results of other physics analyses at the NA62 experiment are summarised