Children are at risk of choking or aspiration and are at increased risk of chest infection. the condition, and side-effect profiles of treatment options. 1. Introduction Myasthenia gravis (MG) is an autoimmune disease in which antibodies are directed at the postsynaptic membrane of the neuromuscular junction, leading to varying degrees of muscle mass weakness and fatigability. Where MG presents before 19 years Sophoridine of age, it is termed juvenile myasthenia gravis (JMG). Although JMG shares many features with the more common adult MG, there are numerous important differences. In this paper we discuss the pathogenesis, epidemiology, presentation, treatment, and end result of JMG and spotlight some of the clinical features and difficulties particular to paediatric patients. 2. Pathogenesis In the majority of cases MG is usually caused by antibodies to the nicotinic acetylcholine receptor (AChR). Antibodies to the AChR are found in over 80% adults with generalised disease but only in 55% of adults with weakness confined to the oculomotor muscle tissue. Patients with AChR antibodies are often referred to as seropositive. AChR antibodies are probably less frequent in prepubertal patients than in adolescent and adult patients [1, 2] (observe Table 1). Antibodies to muscle-specific kinase (MuSK) and to Leucine Sophoridine rich protein 4 (LRP4) have been reported in some seronegative patients. Table 1 Comparisons of prepubertal and postpubertal features of JMG. [1, 2]68C92%[1, 2]80C90% [17, 18]23C43%[16, 19]79%  [1, 2, 20]26% 38%  Open in a separate window Child years myasthenias encompass JMG, which is the subject of this paper; congenital myasthenic syndromes, a heterogeneous group of genetically inherited disorders of the neuromuscular junction ; transient neonatal myasthenia, which results from placental transfer of maternal AChR (or very occasionally MuSK antibodies) to infants of mothers with autoimmune MG . 3. Epidemiology and Clinical Features JMG is usually a rare disorder of child years, but its incidence and prevalence vary geographically. Precise data on incidence and prevalence are not known. Paediatric presentation of MG is usually more common in Oriental than in Caucasian populations . Up to 50% of all cases of MG in Sophoridine Chinese populations present in childhood, mostly with ocular features, with a peak age at presentation of 5C10 years . Caucasian patients, in contrast, are more likely to present in adulthood [7, 8], with prepubertal onset in less than 10% cases [2, 9]. The most frequent clinical presentation of JMG is with ptosis, which is usually often associated with other ocular symptoms namely unilateral or asymmetric ophthalmoplegia, strabismus, and lid twitch, which may only be elicited after sustained upgaze . These symptoms cause particular problems in children as, if severe, they may cause prolonged amblyopia . Most children also develop generalised muscle mass weakness, which presents as painless fatigability of the bulbar and limb musculature, with resultant dysphonia, dysphagia, and proximal limb weakness. Weakness is usually often fluctuating and usually becomes more pronounced through the day and enhances with rest. Children are at risk of choking or aspiration and are at increased risk of chest infection. Occasionally, impairment of the respiratory muscle Sophoridine tissue necessitates ventilatory support. This is known as myasthenic crisis. Prepubertal children presenting with JMG have some interesting and unique clinical features compared with those who present around or after puberty [1, 2]. Prepubertal JMG is usually more likely to manifest as ocular myasthenia . There is an equivalent male: female ratio , in contrast to the female predominance that is seen in peri-/postpubertal children, and a better prognosis, with a higher rate of spontaneous remission in prepubertal presenters [1, 12]. Peri- or postpubertal patients presenting with JMG share more similarities with adult-onset MG (observe Table 1). Ocular myasthenia gravis (OMG) is usually, by definition, MG restricted to the oculomotor muscle tissue for 2 years without becoming generalised . In adult populations up to 80% patients with OMG at presentation will progress to generalised disease [8, 9, 15]. Case series in children (using a variety of treatment protocols and follow-up intervals) MCM2 have reported lower rates of generalisation than adults . Progression may be even less frequent in prepubertal children [17, 18]. 3.1. Transient Neonatal Myasthenia This results from transfer of maternal AChR antibodies across the placenta leading to defects of neuromuscular.