Twin T an identical twin remained in hospital

Twin 2 (T2), an identical twin, remained in hospital for 38 days after childbirth complications, but her further neurological, psychological and motor development was normal. She started migrane onset at 9 yo. At 14, she reported symptoms directly related to excess sleepiness interfering in her everyday activities. At that time, her parents noticed sleep talk and agitated sleep. She had her first cataplexy episode at the same age as T1, 17 years old. She continuously complained of excessive sleepiness, and excessive irritability. Unlike T1, T2 did not have sleep paralysis or hypnagogic hallucinations, nor were there complaints related to cognitive performance (Table 1). During initial clinical follow-up (before results of the exams) the patient frequently complained of sleepiness during the day, excessive irritability, tiredness, constant fatigue relieved by short naps (30min) during daytime, and frequent cataplexy episodes. The polysomnography and MSLT endorsed the clinical diagnostic of narcolepsy with cataplexy (Table 2). The determination of HLA haplotype (A2, A26, B49, B57, DR1, DR7, DR53, DQ2 and DQ5) did not show the presence of smad inhibitor associated with genetic susceptibility to narcolepsy (Table 1).
Discussion Narcolepsy usually occurs sporadically, but may also show a familiar pattern. Estimates of familial incidence range from 4.3% of all narcolepsy cases in Japan to 9.9% in Canada, and, the risk of a first-degree relative of a patient having narcolepsy–cataplexy is 1–2% (10–40 times higher than the prevalence for the general population) which suggests a genetic etiology. Eight of the 18 monozygotic twin pairs described in the literature were described as concordant for the narcolepsy diagnosis, and only three pairs were considered “positive HLA” [5,12–14]. In other words, most monozigotic twin pairs are discordant for narcolepsy suggesting that nongenetic, and even possible, environmental factors can also be involved in the pathophysiology of human narcolepsy. In the present cases, the presence of alleles associated with a certain kind of genetic susceptibility (HLA) to narcolepsy was not detected. The present paper endorses the hypothesis of the possible involvement of other genes (besides HLA) such as T-cell receptor alpha (TCRA) locus[15] as well as also possible neuro-imuno-genetical interactions with a restricted harmful process involving the neurons controlling hypocretin neurotransmission [16]. Unfortunately, after 2004, the patients described above, could not be found for further evaluations (such as cerebrospinal fluid hypocretin-1 testing).
Acknowledgments
Introduction Narcolepsy is a chronic neurological disease characterized by diurnal excessive sleepiness (DES), sleep paralysis, hypnagogic or hypnopompic hallucinations and cataplexy [1]. Narcolepsy with cataplexy represents about 60–70% of all attended cases in treatment centers for these patients [2,3]. Actually, we know that narcolepsy with cataplexy and the deficiency of hypocretin are associated with polymorphism of the human leukocyte antigen HLA-DQB1⁎0602, altered levels of CD40L and T cell receptors, suggesting that an autoimmune process might be involved [3]. Narcolepsy affects 1 in every 2000–4000 individuals in the general population and the treatment aims to control the diurnal excessive sleepiness (DES), nocturnal complaints of sleep fragmentation, cataplexy and psychosocial adaptation [4,5]. DES is treated with sleep hygiene measures, programmed naps and social measures (working time adaptation to accommodate for naps). Stimulant medications are also utilized to increase awareness, such as modafinil and methylfenidate [2]. For the control of cataplexy, tricyclic antidepressants can be used, serotonin-reuptake inhibitor antidepressants and dual antidepressants, besides some other drugs such as sodium hydroxybutyrate (not available in Brazil) [4].