Sleep Disorder Kleine-Levin Syndrome (KLS) Joins the List of Polygenic Brain Disorders Associated with Obstetric Complications.

Kleine-Levin Syndrome is a rare neurological disorder with onset typically during adolescence that is characterized by recurrent episodes of hypersomnia, behavioral changes, and cognitive abnormalities, in the absence of structural changes in neuroimaging. As for many functional brain disorders, the exact disease mechanism in Kleine-Levin Syndrome is presently unknown, preventing the development of specific treatment approaches or protective measures. Here we review the pathophysiology and genetics of this functional brain disorder and then present a specific working hypothesis. A neurodevelopmental mechanism has been suspected based on associations with obstetric complications. Recent studies have focused on genetic factors whereby the first genome-wide association study (GWAS) in Kleine-Levin Syndrome has defined a linkage at the TRANK1 locus. A Gene x Environment interaction model involving obstetric complications was proposed based on concepts developed for other functional brain disorders. To stimulate future research, we here performed annotations of the genes under consideration for Kleine-Levin Syndrome in relation to factors expected to be associated with obstetric complications. Annotations used data-mining of gene/protein lists related to for hypoxia, ischemia, and vascular factors and targeted literature searches. Tentative links for TRANK1, four additional genes in the TRANK1 locus, and LMOD3-LMO2 are described. Protein interaction data for TRANK1 indicate links to CBX2, CBX4, and KDM3A, that in turn can be tied to hypoxia. Taken together, the neurological sleep disorder, Kleine-Levin Syndrome, shows genetic and mechanistic overlap with well analyzed brain disorders such as schizophrenia, autism spectrum disorder and ADHD in which polygenic predisposition interacts with external events during brain development, including obstetric complications.

Kleine-Levin syndrome is associated with birth difficulties and genetic variants in the TRANK1 gene loci.

Kleine-Levin syndrome (KLS) is a rare disorder characterized by severe episodic hypersomnia, with cognitive impairment accompanied by apathy or disinhibition. Pathophysiology is unknown, although imaging studies indicate decreased activity in hypothalamic/thalamic areas during episodes. Familial occurrence is increased, and risk is associated with reports of a difficult birth. We conducted a worldwide case-control genome-wide association study in 673 KLS cases collected over 14 y, and ethnically matched 15,341 control individuals. We found a strong genome-wide significant association (rs71947865, Odds Ratio [OR] = 1.48, P = 8.6 × 10-9) within the 3'region of TRANK1 gene locus, previously associated with bipolar disorder and schizophrenia. Strikingly, KLS cases with rs71947865 variant had significantly increased reports of a difficult birth. As perinatal outcomes have dramatically improved over the last 40 y, we further stratified our sample by birth years and found that recent cases had a significantly reduced rs71947865 association. While the rs71947865 association did not replicate in the entire follow-up sample of 171 KLS cases, rs71947865 was significantly associated with KLS in the subset follow-up sample of 59 KLS cases who reported birth difficulties (OR = 1.54, P = 0.01). Genetic liability of KLS as explained by polygenic risk scores was increased (pseudo R2 = 0.15; P < 2.0 × 10-22 at P = 0.5 threshold) in the follow-up sample. Pathway analysis of genetic associations identified enrichment of circadian regulation pathway genes in KLS cases. Our results suggest links between KLS, circadian regulation, and bipolar disorder, and indicate that the TRANK1 polymorphisms in conjunction with reported birth difficulties may predispose to KLS.

Twin Data: The Lives That Drive the Findings/Twin Research Reviews: Twin Concordance for Kleine-Levin Syndrome; Twin Study of Political Discussion; Twin Relationship Quality and Urinary Cortisol Level; Twin Research Guide/In the News: Twins' Same Day Deliveries; Death of a Twin Holocaust Survivor; Identical Vindman Twins; Twin Festival in France; Tiniest Twins.

Twin data and the results generated by research are driven by the behavioral and physical attributes of twin participants. However, many investigators working with twin data have limited personal contact with actual twin-pairs. This situation may be limiting with respect to interpretation of results and formulation of new hypotheses. In an attempt to rectify this issue, key aspects of the interconnected lives of co-twins in three monozygotic male twin-pairs are presented. The section that follows includes a review of twin research on Kleine-Levin syndrome, political discussion, twin relationship quality and urinary cortisol level, and guidelines for determining sample sizes. The final part of this report presents twin-related news items relating to twins' same day deliveries, death of a twin Holocaust survivor, the Vindman twins, a twin festival in France and the tiniest twins on record.

Kleine-Levin syndrome is associated with LMOD3 variants.

Kleine-Levin syndrome (KLS) is a rare periodic hypersomnia with associated behavioural abnormalities but with often favourable prognosis. There is excess risk of KLS in first-degree relatives, suggesting a strong genetic contribution. So far, no mutation is identified in KLS and comprehensive genetic analysis of affected individuals is lacking. Here we performed whole genome single-nucleotide polymorphism (SNP) genotyping and exome sequencing in a large family with seven affected members. The identified gene with a mutation was resequenced in 38 sporadic KLS patients and the expression of the gene product was mapped in the mouse brain. Linkage analysis mapped the disease locus to chromosome 3 and exome analysis identified a heterozygous missense variant in LMOD3 (p.E142D) in the linkage interval. The variant was found to segregate in all affected and one presumably unaffected member of the family. Resequencing LMOD3 in 38 other KLS patients and their families revealed three other low frequency or rare missense variants in seven cases that were inherited with incomplete penetrance. LMOD3 is expressed in the brain and colocalized with major structures involved in the regulation of vigilance states. LMOD proteins are structural proteins and seem to be developmentally regulated. Our findings suggest that KLS might be a structural/neurodevelopmental brain disease.

Kleine-Levin syndrome: clues to aetiology.

Kleine-Levin syndrome (KLS) is the commonest recurrent sleep disorder, with a prevalence of 1-2 per million population. Clear diagnostic criteria are now defined, but effective treatment remains elusive. The significant body of published literature allows consideration of possible aetiological mechanisms, an understanding of which could guide the development of therapeutic strategies. Functional imaging studies have been inconclusive; although diencephalic abnormalities are a common finding, no consistent pattern has emerged, and these studies have not revealed the mechanism(s) underlying the development of the abnormalities detected. An autoimmune aetiology is consistent with the available data. In this review, we argue that, in order to further our understanding of KLS, there needs to be a co-ordinated international effort to standardise approaches to functional imaging studies, genetic analyses that specifically address the possibility of an autoimmune aetiology, and clinical trials of immunosuppressive therapies.

Familial Kleine-Levin Syndrome: A Specific Entity?

STUDY OBJECTIVES: Kleine-Levin syndrome (KLS) is a rare, mostly sporadic disorder, characterized by intermittent episodes of hypersomnia plus cognitive and behavior disorders. Although its cause is unknown, multiplex families have been described. We contrasted the clinical and biological features of familial versus sporadic KLS. METHODS: Two samples of patients with KLS from the United States and France (n = 260) were studied using clinical interviews and human leukocyte antigen (HLA) genotyping. A multiplex family contained two or more first- or second-degree affected relatives (familial cases). RESULTS: Twenty-one patients from 10 multiplex families (siblings: n = 12, including two pairs of monozygotic twins; parent-child: n = 4; cousins: n = 2; uncle-nephews: n = 3) and 239 patients with sporadic KLS were identified, yielding to 4% multiplex families and 8% familial cases. The simplex and multiplex families did not differ for autoimmune, neurological, and psychiatric disorders. Age, sex ratio, ethnicity, HLA typing, karyotyping, disease course, frequency, and duration of KLS episodes did not differ between groups. Episodes were less frequent in familial versus sporadic KLS (2.3 ± 1.8/y versus 3.8 ± 3.7/y, P = 0.004). Menses triggered more frequently KLS onset in the nine girls with familial KLS (relative risk, RR = 4.12, P = 0.03), but not subsequent episodes. Familial cases had less disinhibited speech (RR = 3.44, P = 0.049), less combined hypophagia/hyperphagia (RR = 4.38, P = 0.006), more abrupt termination of episodes (RR = 1.45, P = 0.04) and less postepisode insomnia (RR = 2.16, P = 0.008). There was similar HLA DQB1 distribution in familial versus sporadic cases and no abnormal karyotypes. CONCLUSION: Familial KLS is mostly present in the same generation, and is clinically similar to but slightly less severe than sporadic KLS.

Kleine-Levin syndrome. Familial cases and comparison with sporadic cases.

OBJECTIVES: To highlight the occurrence of familial cases and addresses, whether familial Kleine-Levine syndrome (KLS) presents the same spectrum of disease, as that seen in sporadic KLS.   METHODS: Between September and December 2014, reports of familial cases of KLS were identified by searching the Library of Congress, PubMed, and Web of Science databases restricted to the English language, with no restriction on date of publication. All cases were reviewed to identify familial cases consistent with current diagnostic criteria for sporadic KLS.   RESULTS: Six reviews and 11 case reports describing cases of familial KLS were identified. In 17 of the 29 familial cases identified, sufficient clinical details were described to be confident that these cases were familial and consistent with the description of KLS in the International Classification of Sleep Disorders 3rd edition (ICSD-3), and recent detailed reviews of sporadic KLS. CONCLUSION: A significant number of familial cases of KLS have been described that are consistent with the ICSD-3 description of KLS, and indistinguishable from sporadic KLS. This suggests that study of familial KLS using modern genetic techniques may be useful in elucidating the pathogenesis of this rare condition.

[The Kleine-Levin syndrome: new aspects of a rare disease]. / Das Kleine-Levin-Syndrom : Neues von einer seltenen Erkrankung.

The Kleine-Levin syndrome (KLS) is a rare disease which can occur one to several times per year. The KLS belongs to the group of hypersomnia of central origin occurring mainly during the second decade of life after infections, sleep deprivation, alcohol consumption or minor trauma. Early manifestation combined with hypersexuality during symptomatic phases can be a predictor for a long course of the disease, which lasts a mean of 1-27 years. Due to the lack of biological markers diagnosis at first manifestation is difficult. The classical trias of hypersomnia, hyperphagia and hypersexuality can only be found in 45 % of patients. The dominant clinical symptoms are hypersomnia with changes in perception and behavior. Subtraction of perfusion studies performed during symptomatic and asymptomatic phases showed decreased perfusion of the left hypothalamus, thalamus, basal ganglia, medial and dorsolateral frontal and temporal regions. In the few patients who had lumbar punctures in both symptomatic and asymptomatic phases hypocretin-1 was moderately to slightly lowered during symptomatic phases. Meta-analyses showed good therapeutic effects of stimulants on the symptom sleepiness. Lithium reduces the frequency and duration of symptomatic phases. Assuming that KLS is underdiagnosed it should be considered as a differential diagnosis in young patients with recurrent hypersomnia.

Monozygotic twins concordant for Kleine-Levin syndrome.

BACKGROUND: Kleine-Levin syndrome is a rare sleep disorder of unknown etiology. It is characterized by intermittent periods of excessive sleepiness, cognitive disturbances and behavioral abnormalities. Nine cases of familial Kleine-Levin syndrome have been identified, but there are no reported cases describing twins that are affected by the syndrome. CASE PRESENTATION: We report the cases of 16-year-old monozygotic twin boys who both suffered from Kleine-Levin syndrome. In both cases, the onset of the first episode was preceded by an influenza infection. During symptomatic periods they slept for the entire day except for meals and bathroom visits. Actimetry recordings revealed that during symptomatic periods, daily activity was lower than that of asymptomatic periods, on the other hand, activity during the night was significantly higher in symptomatic periods than asymptomatic periods. Polysomnography (PSG) data during symptomatic periods revealed a decrease in sleep efficiency. Human leukocyte antigen (HLA) typing revealed no DQB1*02 loci. They were administered lithium carbonate but the beneficial effect was limited. CONCLUSIONS: Our observations suggest that Kleine-Levin syndrome may be due to genetic and autoimmune processes, although etiologic relationship to specific HLA type remains controversial.

Distribution of HLA-DQB1 alleles in patients with Kleine-Levin syndrome.

Kleine-Levin syndrome (KLS) is a rare disorder characterized by recurrent episodes of hypersomnia, cognitive or behavior disturbances, compulsive eating behavior, and hypersexuality. The etiology of KLS remains unknown even though its clinical symptoms suggest an underlying autoimmune process. In this study, we analyzed the human leukocyte antigen (HLA) typing alleles in Taiwanese patients with KLS using the polymerase chain reaction sequence-specific priming technique. We report that an immunoresponsive HLA-DQB1, DQB1∗0602, was detected in significant quantities in patients with KLS (three of 12, p=0.046) and could elevate the risk of KLS (odds ratio, 1.143; 95% confidence interval, 0.0982-1.329). In conclusion, an identification of genomic susceptibility to KLS will be helpful in determining the immunospecific targeted therapies for patients with KLS.

Validation of the ICSD-2 criteria for CSF hypocretin-1 measurements in the diagnosis of narcolepsy in the Danish population.

STUDY OBJECTIVES: The International Classification of Sleep Disorders (ICSD-2) criteria for low CSF hypocretin-1 levels (CSF hcrt-1) still need validation as a diagnostic tool for narcolepsy in different populations because inter-assay variability and different definitions of hypocretin deficiency complicate direct comparisons of study results. DESIGN AND PARTICIPANTS: Interviews, polysomnography, multiple sleep latency test, HLA-typing, and CSF hcrt-1 measurements in Danish patients with narcolepsy with cataplexy (NC) and narcolepsy without cataplexy (NwC), CSF hcrt-1 measurements in other hypersomnias, neurological and normal controls. Comparisons of hypocretin deficiency and frequency of HLA-DQB1*0602-positivity in the Danish and eligible NC and NwC populations (included via MEDLINE search), by (re)calculation of study results using the ICSD-2 criterion for low CSF hcrt-1 (< 30% of normal mean). MEASUREMENTS AND RESULTS: In Danes, low CSF hcrt-1 was present in 40/46 NC, 3/14 NwC and 0/106 controls (P < 0.0001). Thirty-nine of 41 NC and 4/13 NwC patients were HLA-DQB1*0602-positive (P < 0.01). Hypocretin-deficient NC patients had higher frequency of cataplexy, shorter mean sleep latency, more sleep onset REM periods (P < 0.05) and more awakenings (NS) than did NC patients with normal CSF hcrt-1. Across populations, low CSF hcrt-1 and HLA-DQB1*0602-positivity characterized the majority of NC (80% to 100%, P = 0.53; 80% to 100%, P = 0.11) but a minority of NwC patients (11% to 29%, P = 0.75; 29% to 89%, P = 0.043). CONCLUSION: The study provides evidence that hypocretin deficiency causes a more severe NC phenotype. The ICSD-2 criterion for low CSF hcrt-1 (< 30% of normal mean) is valid for diagnosing NC, but not NwC. HLA-typing should precede CSF hcrt-1 measurements because hypocretin deficiency is rare in HLA-DQB1*0602-negative patients.

Kleine-Levin syndrome: a systematic study of 108 patients.

OBJECTIVE: Kleine-Levin syndrome is a rare disorder characterized by relapsing-remitting episodes of hypersomnia, cognitive disturbances, and behavioral disturbances, such as hyperphagia and hypersexuality. METHODS: We collected detailed clinical data and blood samples on 108 patients, 79 parent pairs, and 108 matched control subjects. We measured biological markers and typed human leukocyte antigen genes DR and DQ. RESULTS: Novel predisposing factors were identified including increased birth and developmental problems (odds ratio, 6.5). Jewish heritage was overrepresented, and five multiplex families were identified. Human leukocyte antigen typing was unremarkable. Patients were 78% male (mean age at onset, 15.7 +/- 6.0 years), averaged 19 episodes of 13 days, and were incapacitated 8 months over 14 years. The disease course was longer in men, in patients with hypersexuality, and when onset was after age 20. During episodes, all patients had hypersomnia, cognitive impairment, and derealization; 66% had megaphagia; 53% reported hypersexuality (principally men); and 53% reported a depressed mood (predominantly women). Patients were remarkably similar to control subjects between episodes regarding sleep, mood, and eating attitude, but had increased body mass index. We found marginal efficacy for amantadine and mood stabilizers, but found no increased family history for neuropsychiatric disorders. INTERPRETATION: The similarity of the clinical and demographic features across studies strongly suggests that Kleine-Levin syndrome is a genuine disease entity. Familial clustering and increased prevalence in the Jewish population support a role for a major genetic susceptibility factor. Considering the inefficacy of available treatments, we propose that disease management should primarily be supportive and educational.

Clinical characteristics and HLA typing of a family with Kleine-Levin syndrome.

BACKGROUND: Kleine-Levin syndrome (KLS) is a rare disorder of unknown etiology. To date, only four familial cases have been described. The possible presence of genetic and autoimmune processes has been postulated recently. Our objective was to report for the first time a multiplex KLS Saudi family with 6 out of 12 family members affected. METHODS: The demographic and clinical features of the six affected family members are described. KLS was diagnosed according to the International Classification of Sleep Disorders (ICSD). Human leukocyte antigen (HLA) typing was performed for both affected and unaffected family members and compared to previous studies. RESULTS: The father and three male and two female children were affected. Age of onset ranged from 15 to 21 years. Symptoms disappeared in four family members. HLA typing was identical in the father and two children (1F and 5M). All affected members shared one-half of HLA antigens. HLA typing revealed that four members out of the six affected members are homozygous at DQB1 *02 loci. CONCLUSIONS: This report provides a description of a multiplex KLS family with six members affected. HLA-DQB1 *02 homozygosity was present in 4/6 affected and 2/6 unaffected family members. The family studied presents an invaluable opportunity for further DNA and genetic studies, which may help in finding the mutation in the future.

Familial Kleine-Levin syndrome: two siblings with unusually long hypersomnic spells.

Kleine-Levin syndrome is a rare, sporadic disorder, with discrete spells of hypersomnolence occurring during adolescence, variously accompanied by megaphagia, behavioral changes, psychosis, and mild autonomic symptoms. Familial cases have not previously been reported. We describe 2 siblings who shared uncharacteristically prolonged episodes of hypersomnolence, and the HLA-DR2 haplotype. In one patient, levels of cerebrospinal fluid orexin (hypocretin) during an attack were normal. The presence of an increased sleep drive, despite the occurrence of large amounts of ostensibly restorative sleep, suggests the possible existence of a disorder of sleep satiety.

Kleine-Levin syndrome: an autoimmune hypothesis based on clinical and genetic analyses.

BACKGROUND: Kleine-Levin syndrome (KLS) is a rare disorder of unknown etiology. Pathophysiologic hypotheses include a hypothalamic dysfunction and abnormalities in the central serotonin and dopamine metabolism. Several clinical symptoms also suggest an underlying autoimmune process. OBJECTIVE: To systematically investigate patients with KLS with reference to the available hypotheses. METHODS: The authors collected clinical, polysomnographic, CSF, CT, and MRI records and analyzed gene polymorphisms of HLA-DQB1, tryptophan hydroxylase (TpH), and catechol-O-methyltransferase (COMT) in 30 unrelated patients with KLS and their families. The genotype data were contrasted with data from a normal control population. RESULTS: Only human leukocyte antigen (HLA)-DQB1*0201 allele frequency was significantly increased in patients with KLS. Three patients with KLS but none of the control subjects were DQB1*0201 homozygous. Two affected subjects from the same family were DQB1*0201 homozygous. In 17 DQB1*0201 heterozygous parents, 11 (64.7%) had transmitted this allele, suggesting a preferential transmission. CONCLUSION: These findings, together with the young age at onset, the recurrence of symptoms, and the frequent infectious precipitating factors, suggest an autoimmune etiology for Kleine-Levin syndrome.

[Sleep disorders and child and adolescent psychiatric illnesses]. / Schlafstörungen bei kinder- und jugendpsychiatrischen Erkrankungen.

As a symptom of many psychiatric disorders of childhood and adolescence, sleep disturbances often complicate the course and treatment of the underlying disorder. A somatic aetiology, e.g., as in Kleine-Levin syndrome or narcolepsy, may lead to diagnostic misinterpretations. It is not clear whether specific alterations of sleep architecture already exist in this age group and are thus trait markers for psychiatric disorders. Although it is well-known that sleep problems in adults, especially insomnia, are important in the later development of depressive syndromes, it is not clear whether persistent sleep problems during childhood constitute markers of vulnerability for psychiatric disorders. This review demonstrates interactions between sleep disturbances and psychiatric disorders of childhood and adolescence and their importance for assessment and therapy.

Electrophysiological and immunogenetic findings in recurrent monosymptomatic-type hypersomnia: a study of two unrelated Italian cases.

MSLT and immunogenetic findings in two unrelated Italian subjects with recurrent monosymptomatic hypersomnia are reported. In both patients MSLT documented a markedly increased daytime sleep propensity during the attacks without augmented REM sleep pressure. Both patients share the same HLA haplotype (HLA-DR1, DQ1) which has been found in Kleine-Levin syndrome. This makes these subtypes of recurrent hypersomnia indistinguishable one from the other, under the immunogenetic profile, but permits differentiation from narcolepsy which is HLA-DR2, DQ1 closely linked.