José L. Vicario

Genome-wide association study identifies new HLA class II haplotypes strongly protective against narcolepsy

Narcolepsy is a rare sleep disorder with the strongest human leukocyte antigen (HLA) association ever reported. Since the associated HLA-DRB1*1501-DQB1*0602 haplotype is common in the general population (15–25%), it has been suggested that it is almost necessary but not sufficient for developing narcolepsy. To further define the genetic basis of narcolepsy risk, we performed a genome-wide association study (GWAS) in 562 European individuals with narcolepsy (cases) and 702 ethnically matched controls, with independent replication in 370 cases and 495 controls, all heterozygous for DRB1*1501-DQB1*0602. We found association with a protective variant near HLA-DQA2 (rs2858884; P < 3 × 10−8). Further analysis revealed that rs2858884 is strongly linked to DRB1*03-DQB1*02 (P < 4 × 10−43) and DRB1*1301-DQB1*0603 (P < 3 × 10−7). Cases almost never carried a trans DRB1*1301-DQB1*0603 haplotype (odds ratio = 0.02; P < 6 × 10−14). This unexpected protective HLA haplotype suggests a virtually causal involvement of the HLA region in narcolepsy susceptibility.

DQB1 locus alone explains most of the risk and protection in narcolepsy with cataplexy in Europe

STUDY OBJECTIVE Prior research has identified five common genetic variants associated with narcolepsy with cataplexy in Caucasian patients. To replicate and/or extend these findings, we have tested HLA-DQB1, the previously identified 5 variants, and 10 other potential variants in a large European sample of narcolepsy with cataplexy subjects. DESIGN Retrospective case-control study. SETTING A recent study showed that over 76% of significant genome-wide association variants lie within DNase I hypersensitive sites (DHSs). From our previous GWAS, we identified 30 single nucleotide polymorphisms (SNPs) with P < 10(-4) mapping to DHSs. Ten SNPs tagging these sites, HLADQB1, and all previously reported SNPs significantly associated with narcolepsy were tested for replication. PATIENTS AND PARTICIPANTS For GWAS, 1,261 narcolepsy patients and 1,422 HLA-DQB1*06:02-matched controls were included. For HLA study, 1,218 patients and 3,541 controls were included. MEASUREMENTS AND RESULTS None of the top variants within DHSs were replicated. Out of the five previously reported SNPs, only rs2858884 within the HLA region (P < 2x10(-9)) and rs1154155 within the TRA locus (P < 2x10(-8)) replicated. DQB1 typing confirmed that DQB1*06:02 confers an extraordinary risk (odds ratio 251). Four protective alleles (DQB1*06:03, odds ratio 0.17, DQB1*05:01, odds ratio 0.56, DQB1*06:09 odds ratio 0.21, DQB1*02 odds ratio 0.76) were also identified. CONCLUSION An overwhelming portion of genetic risk for narcolepsy with cataplexy is found at DQB1 locus. Since DQB1*06:02 positive subjects are at 251-fold increase in risk for narcolepsy, and all recent cases of narcolepsy after H1N1 vaccination are positive for this allele, DQB1 genotyping may be relevant to public health policy.

Clinical, polysomnographic and laboratory characteristics of narcolepsy-cataplexy in a sample of children and adolescents

OBJECTIVE To report our findings from a sample of narcoleptic children and adolescents evaluated in our unit from 1988 to 2005. PATIENTS AND METHODS The sample was composed of nine children (5 boys) with a mean age of 14.5 years at diagnosis. The protocol included the following: Epworth, Ullanlinna narcolepsy scale, and Stanford cataplexy questionnaires; physical, psychological and neurological examinations; neuroimaging; PSG+MSLT recordings; HLA and in two cases Hcrt-1 level in CSF. RESULTS Narcolepsy was sporadic in all cases. The first symptom was EDS with a mean age at onset of 9.4±2.5 years (range 6-13 years). All patients complained of cataplexy. Other symptoms were hypnagogic hallucinations (4 children) and sleep paralysis (3 children). All the children performed poorly at school, 4 had emotional disorders with depression, 4 displayed nocturnal eating and weight gain. Mean BMI was 25.0 kg/m(2). One girl was diagnosed as having precocious puberty, polycystic ovary syndrome (PCOS), hyperandrogenism and insulin resistance. The MRI showed a partial empty sella. Hcrt-1 was undetectable in her CSF. The mean Ullanlinna score was 24.6; PSG showed disturbed nocturnal sleep and the MSLT showed a mean sleep latency of 2.1 min and 3 SOREMPs. Eight children were DR2-DQ1-positive, whereas one boy was DR2-negative but DQ1-positive. In two patients, Hcrt-1 was undetectable. All children, in addition to scheduled naps during the day, were treated with modafinil or methylphenidate combined with an antidepressant and in two cases with sodium oxybate. CONCLUSION NC was sporadic in all children and associated with precocious puberty and PCOS, hyperandrogenism and insulin resistance in one case. EDS, cataplexy, disturbed nocturnal sleep, nocturnal eating, poor school performance, and emotional disorders were the principal complaints. All patients had DQB1∗0602 and Hcrt-1 was evaluated in two cases (undetectable in both).

A Missense Mutation in Myelin Oligodendrocyte Glycoprotein as a Cause of Familial Narcolepsy with Cataplexy

Narcolepsy is a rare sleep disorder characterized by excessive daytime sleepiness and cataplexy. Familial narcolepsy accounts for less than 10% of all narcolepsy cases. However, documented multiplex families are very rare and causative mutations have not been identified to date. To identify a causative mutation in familial narcolepsy, we performed linkage analysis in the largest ever reported family, which has 12 affected members, and sequenced coding regions of the genome (exome sequencing) of three affected members with narcolepsy and cataplexy. We successfully mapped a candidate locus on chromosomal region 6p22.1 (LOD score ¼ 3.85) by linkage analysis. Exome sequencing identified a missense mutation in the second exon of MOG within the linkage region. A c.398C>G mutation was present in all affected family members but absent in unaffected members and 775 unrelated control subjects. Transient expression of mutant myelin oligodendrocyte glycoprotein (MOG) in mouse oligodendrocytes showed abnormal subcellular localization, suggesting an altered function of the mutant MOG. MOG has recently been linked to various neuropsychiatric disorders and is considered as a key autoantigen in multiple sclerosis and in its animal model, experimental autoimmune encephalitis. Our finding of a pathogenic MOG mutation highlights a major role for myelin and oligodendrocytes in narcolepsy and further emphasizes glial involvement in neurodegeneration and neurobehavioral disorders. [corrected].

Narcolepsy with cataplexy and comorbid immunopathological diseases

Evidence suggests that autoimmune diseases tend to co‐occur so that patients with an autoimmune disorder are at higher risk of a second autoimmune disease. The association between allergic and autoimmune diseases is also of considerable interest. There are no reports on the association between sporadic or familial narcolepsy with cataplexy and other non‐neurological immune‐mediated diseases. This study reported on the comorbid immunopathological diseases associated with narcolepsy. One‐hundred and fifty six narcoleptic patients with a mean age at diagnosis of 39.1 ± 17.8 years (range, 6–70 years) were assessed using the clinical history, physical and neurological examinations, sleep questionnaires, neuroimaging and human leucocyte antigen typing. Diagnosis was confirmed by polysomnography followed by a multiple sleep latency test or by measuring hypocretin‐1 levels. Patients with immunopathological diseases were matched for gender and age at the onset of narcoleptic symptoms with narcoleptic patients without immunopathological diseases. Twenty‐six patients (16.6%; 50% women; one familial, 25 sporadic) had one or more immunopathological diseases associated: autoimmune diseases, such as idiopathic thrombocytopenic purpura, multiple sclerosis, systemic lupus erythematosus, psoriasis, Crohns disease, ulcerative colitis, autoimmune thyroid disease, Peyronies disease and idiopathic recurrent facial palsy; other immunopathological diseases, like atopic dermatitis, allergic asthma and allergic rhinitis. Although not significant, the age at diagnosis of narcolepsy was 9.3 years earlier in patients with narcolepsy + immunopathological diseases. The results demonstrate that the prevalence of comorbid immunopathological diseases is high in narcolepsy, and cataplexy is significantly more severe in patients with narcolepsy + immunopathological diseases.

Comorbidity of Narcolepsy Type 1 With Autoimmune Diseases and Other Immunopathological Disorders: A Case-Control Study

Background Several evidences suggest that autoimmune diseases (ADs) tend to co-occur in an individual and within the same family. Narcolepsy type 1 (NT1) is a chronic sleep disorder caused by a selective loss of hypocretin-producing neurons due to a mechanism of neural destruction that indicates an autoimmune pathogenesis, although no evidence is available. We report on the comorbidity of ADs and other immunopathological diseases (including allergy diseases) in narcolepsy. Methods We studied 158 Caucasian NT1 patients (60.7% male; mean age 49.4 ± 19.7 years), in whom the diagnosis was confirmed by polysomnography followed by a multiple sleep latency test, or by hypocretin-1 levels measurements. Results Thirty out of 158 patients (18.99%; 53.3% female; 29 sporadic and one familial cases) had one or more immunopathological diseases associated. A control group of 151 subjects were matched by gender and age with the narcolepsy patients. Results demonstrated that there was a higher frequency of ADs in our series of narcolepsy patients compared to the sample of general population (odds ratio: 3.17; 95% confidence interval: 1.01 - 10.07; P = 0.040). A temporal relationship with the age at onset of the diseases was found. Conclusions Cataplexy was significantly more severe in NT1 patients with immunopathological diseases, and immunopathological diseases are a risk factor for severe forms of cataplexy in our series (odds ratio: 23.6; 95% confidence interval: 5.5 - 100.1).

Narcolepsy-cataplexy induced by a cow milk oral immunotherapy protocol?

To the editor, We recently observed recurrent hypersomnia in a 24-year-old man, which had been occurring several times a year since the patient was 13 years old. He also suffered from episodic hyperphagia and hypersexuality. A diagnosis of Kleine–Levin syndrome (KLS) was made. Brain MRI was normal. He was positive for HLA DQB1 02 typing, and a moderate hypoperfusion in basal ganglia was found using brain SPECT. After treatment failure with lithium (1200 mgr/day) the patient manifested continuous cycle, alternating periods of pseudohypersomnia, true hypersomnia and normal period, without interruption. He displayed progressive pseudohypersomnia (drowsy and apathetic but unable to sleep), profuse sweating, seborrhea and facial flushing [1,2], for 10–12 days then later displayed true hypersomnia, sleeping 20–22 h/day for 3–4 days. Finally, there was a normal period lasting 8–10 days, preceded by a brief period of insomnia for 1–2 days. After progressive worsening, coupled with alcohol consumption to induce sleep and the emergence of suicidal thoughts, we started treatment with 4 gm/night of sodium oxybate (SO) during the patient’s pseudo-hypersomnia with positive results. The patient was feeling rested and remembered dreams, something that did not happen in the past. He worsened again with temporary treatment withdrawal. We restarted treatment with SO and performed polysomnographic studies. A gradual improvement in sleep efficiency and REM sleep percentage was observed, without any change in slow wave sleep. Results were excellent after reaching 7–8 gm/night. The patient remained asytomatic after 30 months of treatment. We suggest that SO may be an alternative option for KLS, which is difficult to treat and its pathophysiology remains unknown [3]. Conflict of Interest

Three new HLA class I alleles with synonymous mutations: HLA-A*03:01:62 , -C*07:02:82 and -C*12:03:42

Three new HLA class I alleles with synonymous mutations were identified.

Report From the First and Second Spanish Killer Immunoglobulin-Like Receptor Genotyping Workshops: External Quality Control for Natural Killer Alloreactive Donor Selection in Haploidentical Stem Cell Transplantation

An important factor affecting the success in the setting of related haploidentical hematopoietic stem cell transplantation (HSCT) is the graft-versus-leukemia effect mediated by natural killer (NK) cells when the donor displays NK alloreactivity versus the recipient. NK cell function is regulated by killer immunoglobulin-like receptors (KIR) and it has been described that donor KIR genotype influences transplantation outcome. This has led to a requirement of laboratories to have a quality assurance program for validation and control of their KIR genotyping methods. The goal of the 1st and 2nd Spanish KIR Genotyping Workshops was to provide an external proficiency testing program in KIR genotyping for Spanish immunology and transplant laboratories. These workshops were conducted during the years 2014-2016 and consisted of 17 participating laboratories typing a set of 20 samples. The presence/absence of 16 mandatory KIR loci (2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 2DP1, 3DL1, 3DL2, 3DL3, 3DS1, and 3DP1) was evaluated per sample. Methods for KIR genotyping included polymerase chain reaction with the use of sequence-specific primers and sequence-specific oligoprobes. Consensus typing was reached in all samples, and the performance of laboratories in external proficiency testing was satisfactory in all cases. The polymorphism detected in the small sample studied in both workshops is indicative of an ample variety of KIR gene profiles in the Spanish population.

Characterization of the novel HLA-A*80:04 allele identified in a Spanish volunteer donor

HLA‐A*80:04 shows one amino acid replacement, A76 > E, when compared with the A*80:01 allele.