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 x 10(-8)). Further analysis revealed that rs2858884 is strongly linked to DRB1*03-DQB1*02 (P < 4 x 10(-43)) and DRB1*1301-DQB1*0603 (P < 3 x 10(-7)). Cases almost never carried a trans DRB1*1301-DQB1*0603 haplotype (odds ratio = 0.02; P < 6 x 10(-14)). This unexpected protective HLA haplotype suggests a virtually causal involvement of the HLA region in narcolepsy susceptibility.

Deletions of 11q22.3-q25 are associated with atypical lung carcinoids and poor clinical outcome

Carcinoids are slow-growing neuroendocrine tumors that, in the lung, can be subclassified as typical (TC) or atypical (AC). To identify genetic alterations that improve the prediction of prognosis, we investigated 34 carcinoid tumors of the lung (18 TCs, 15 ACs, and 1 unclassified) by using array comparative genomic hybridization (array CGH) on 3700 genomic bacterial artificial chromosome arrays (resolution ?1 Mb). When comparing ACs with TCs, the data revealed: i) a significant difference in the average number of chromosome arms altered (9.6 versus 4.2, respectively; P = 0.036), with one subgroup of five ACs having more than 15 chromosome arms altered; ii) chromosomal changes in 30% of ACs or more with additions at 9q (?1 Mb) and losses at 1p, 2q, 10q, and 11q; and iii) 11q deletions in 8 of 15 ACs versus 1 of 18 TCs (P = 0.004), which was confirmed via fluorescence in situ hybridization. The four critical regions of interest in 45% ACs or more comprised 11q14.1, 11q22.1-q22.3, 11q22.3-q23.2, and 11q24.2-q25, all telomeric of MEN1 at 11q13. Results were correlated with patient clinical data and long-term follow-up. Thus, there is a strong association of 11q22.3-q25 loss with poorer prognosis, alone or in combination with absence of 9q34.11 alterations (P = 0.0022 and P = 0.00026, respectively).

Persistent decline in estimated but not measured glomerular filtration rate on tenofovir may reflect tubular rather than glomerular toxicity

Tenofovir disoproxil fumarate (TDF) has been associated with proximal renal tubulopathy and reduction in estimated glomerular filtration rate (eGFR), without accounting for the tubular secretion of creatinine.

A comparison of measured and estimated glomerular filtration rate in successfully treated HIV-patients with preserved renal function

Monitoring of renal function becomes increasingly important in the aging population of HIV-1 infected patients. We compared Cockroft & Gault (C&G), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Modification of Diet in Renal Disease (MDRD), Cystatin C- and 24 h urine-based estimated GFR (eGFR) with the gold standard, measured GFR (mGFR) using [125I]-iothalamate.

Liver breath tests non-invasively predict higher stages of non-alcoholic steatohepatitis

Effectively assessing subtle hepatic metabolic functions by novel non-invasive tests might be of clinical utility in scoring NAFLD (non-alcoholic fatty liver disease) and in identifying altered metabolic pathways. The present study was conducted on 39 (20 lean and 19 obese) hypertransaminasemic patients with histologically proven NAFLD {ranging from simple steatosis to severe steatohepatitis [NASH (non-alcoholic steatohepatitis)] and fibrosis} and 28 (20 lean and eight overweight) healthy controls, who underwent stable isotope breath testing ([(13)C]methacetin and [(13)C]ketoisocaproate) for microsomal and mitochondrial liver function in relation to histology, serum hyaluronate, as a marker of liver fibrosis, and body size. Compared with healthy subjects and patients with simple steatosis, NASH patients had enhanced methacetin demethylation (P=0.001), but decreased (P=0.001) and delayed (P=0.006) ketoisocaproate decarboxylation, which was inversely related (P=0.001) to the degree of histological fibrosis (r=-0.701), serum hyaluronate (r=-0.644) and body size (r=-0.485). Ketoisocaproate decarboxylation was impaired further in obese patients with NASH, but not in patients with simple steatosis and in overweight controls. NASH and insulin resistance were independently associated with an abnormal ketoisocaproate breath test (P=0.001). The cut-off value of 9.6% cumulative expired (13)CO(2) for ketoisocaproate at 60 min was associated with the highest prediction (positive predictive value, 0.90; negative predictive value, 0.73) for NASH, yielding an overall sensitivity of 68% and specificity of 94%. In conclusion, both microsomal and mitochondrial functions are disturbed in NASH. Therefore stable isotope breath tests may usefully contribute to a better and non-invasive characterization of patients with NAFLD.

Terlipressin as an adjunct vasopressor in refractory hypotension after tricyclic antidepressant intoxication

AIM OF STUDY: To report the management of cardiovascular failure refractory to standard catecholamine therapy with terlipressin in a patient with tricyclic antidepressant (TCA) intoxication. CASE REPORT: A 41-year-old woman, with suicidal ingestion of 11.25 g amitriptyline and 1500 mg diclofenac, was admitted to the emergency department. After 30 min in ventricular fibrillation, with ongoing CPR, she regained a potentially perfusing rhythm, but with hypotension refractory to standard catecholamine therapy with adrenaline, 2 microg/kg/min (norepinephrine); adrenaline, 1 microg/kg/min (epinephrine) until 55 min after admission. An injection of 1 mg terlipressin restored mean arterial blood pressure >65 mmHg within 10 min. Ten hours after admission to the intensive care unit, catecholamine support could be withdrawn because of a stable haemodynamic state. Within 7 days, all organ function recovered, and the patient regained full neurological function. CONCLUSIONS: Successful management of cardiovascular failure with terlipressin after TCA intoxication refractory to catecholamines suggests a potential role for terlipressin as an adjunct vasopressor in severely hypotensive patients.

Development of a genotyping microarray for Usher syndrome

BACKGROUND: Usher syndrome, a combination of retinitis pigmentosa (RP) and sensorineural hearing loss with or without vestibular dysfunction, displays a high degree of clinical and genetic heterogeneity. Three clinical subtypes can be distinguished, based on the age of onset and severity of the hearing impairment, and the presence or absence of vestibular abnormalities. Thus far, eight genes have been implicated in the syndrome, together comprising 347 protein-coding exons. METHODS: To improve DNA diagnostics for patients with Usher syndrome, we developed a genotyping microarray based on the arrayed primer extension (APEX) method. Allele-specific oligonucleotides corresponding to all 298 Usher syndrome-associated sequence variants known to date, 76 of which are novel, were arrayed. RESULTS: Approximately half of these variants were validated using original patient DNAs, which yielded an accuracy of >98%. The efficiency of the Usher genotyping microarray was tested using DNAs from 370 unrelated European and American patients with Usher syndrome. Sequence variants were identified in 64/140 (46%) patients with Usher syndrome type I, 45/189 (24%) patients with Usher syndrome type II, 6/21 (29%) patients with Usher syndrome type III and 6/20 (30%) patients with atypical Usher syndrome. The chip also identified two novel sequence variants, c.400C>T (p.R134X) in PCDH15 and c.1606T>C (p.C536S) in USH2A. CONCLUSION: The Usher genotyping microarray is a versatile and affordable screening tool for Usher syndrome. Its efficiency will improve with the addition of novel sequence variants with minimal extra costs, making it a very useful first-pass screening tool.

Identification of novel mutations in X-linked retinitis pigmentosa families and implications for diagnostic testing

PURPOSE: The goal of this study was to identify mutations in X-chromosomal genes associated with retinitis pigmentosa (RP) in patients from Germany, The Netherlands, Denmark, and Switzerland. METHODS: In addition to all coding exons of RP2, exons 1 through 15, 9a, ORF15, 15a and 15b of RPGR were screened for mutations. PCR products were amplified from genomic DNA extracted from blood samples and analyzed by direct sequencing. In one family with apparently dominant inheritance of RP, linkage analysis identified an interval on the X chromosome containing RPGR, and mutation screening revealed a pathogenic variant in this gene. Patients of this family were examined clinically and by X-inactivation studies. RESULTS: This study included 141 RP families with possible X-chromosomal inheritance. In total, we identified 46 families with pathogenic sequence alterations in RPGR and RP2, of which 17 mutations have not been described previously. Two of the novel mutations represent the most 3'-terminal pathogenic sequence variants in RPGR and RP2 reported to date. In exon ORF15 of RPGR, we found eight novel and 14 known mutations. All lead to a disruption of open reading frame. Of the families with suggested X-chromosomal inheritance, 35% showed mutations in ORF15. In addition, we found five novel mutations in other exons of RPGR and four in RP2. Deletions in ORF15 of RPGR were identified in three families in which female carriers showed variable manifestation of the phenotype. Furthermore, an ORF15 mutation was found in an RP patient who additionally carries a 6.4 kbp deletion downstream of the coding region of exon ORF15. We did not identify mutations in 39 sporadic male cases from Switzerland. CONCLUSIONS: RPGR mutations were confirmed to be the most frequent cause of RP in families with an X-chromosomal inheritance pattern. We propose a screening strategy to provide molecular diagnostics in these families.