Efficient strategy for the molecular diagnosis of intellectual disability using targeted high-throughput sequencing.

BACKGROUND: Intellectual disability (ID) is characterised by an extreme genetic heterogeneity. Several hundred genes have been associated to monogenic forms of ID, considerably complicating molecular diagnostics. Trio-exome sequencing was recently proposed as a diagnostic approach, yet remains costly for a general implementation. METHODS: We report the alternative strategy of targeted high-throughput sequencing of 217 genes in which mutations had been reported in patients with ID or autism as the major clinical concern. We analysed 106 patients with ID of unknown aetiology following array-CGH analysis and other genetic investigations. Ninety per cent of these patients were males, and 75% sporadic cases. RESULTS: We identified 26 causative mutations: 16 in X-linked genes (ATRX, CUL4B, DMD, FMR1, HCFC1, IL1RAPL1, IQSEC2, KDM5C, MAOA, MECP2, SLC9A6, SLC16A2, PHF8) and 10 de novo in autosomal-dominant genes (DYRK1A, GRIN1, MED13L, TCF4, RAI1, SHANK3, SLC2A1, SYNGAP1). We also detected four possibly causative mutations (eg, in NLGN3) requiring further investigations. We present detailed reasoning for assigning causality for each mutation, and associated patients' clinical information. Some genes were hit more than once in our cohort, suggesting they correspond to more frequent ID-associated conditions (KDM5C, MECP2, DYRK1A, TCF4). We highlight some unexpected genotype to phenotype correlations, with causative mutations being identified in genes associated to defined syndromes in patients deviating from the classic phenotype (DMD, TCF4, MECP2). We also bring additional supportive (HCFC1, MED13L) or unsupportive (SHROOM4, SRPX2) evidences for the implication of previous candidate genes or mutations in cognitive disorders. CONCLUSIONS: With a diagnostic yield of 25% targeted sequencing appears relevant as a first intention test for the diagnosis of ID, but importantly will also contribute to a better understanding regarding the specific contribution of the many genes implicated in ID and autism.

Obstructive Sleep Apnea and Hypopnea Efficacy and Safety of a Long-Acting beta2-Agonist.

The effect of inhaled long-acting beta2-agonists in obstructive sleep apnea syndrome (OSAS) is unknown, although from the pharmacological point of view both therapeutic and adverse effects need to be considered. The purpose of this study was to obtain data on the efficacy and safety of salmeterol in patients with OSAS. In a randomized, double-blind, placebo-controlled, cross-over study, effects of salmeterol on respiration during sleep and sleep quality were investigated in 20 patients with OSAS. Of these, 4 patients were female, 16 male; the average age was 53.0 +/- 7.8 years, with average body mass index 28.0 +/- 3.0 kg small middle dot m(-2) and average apnea hypopnea index 35.6 +/- 17.8 h(-1). Patients with asthma, chronic obstructive pulmonary disease (COPD), and left heart failure were excluded. Placebo or verum (50 &mgr;g salmeterol) was administered at 7 pm by meter dose inhaler and spacer device. All patients underwent full polysomnography during baseline, placebo, and verum night. Statistical analysis was performed by StudentOs t-test (p > 0.05). Between the placebo and verum there were no differences in total sleep time, sleep stages, apnea index (AI), apnea hypopnea index (AHI), and nadir oxygen saturation. There was, however, 1) a significant deterioration of mean oxygen saturation (SaO2m; placebo 93.1 +/- 2.0 vs. verum 92.5 +/- 2.2%; p = 0.01), 2) of percent of time spent with an oxygen saturation (SaO2)

20 ans après: a second mutation in MAOA identified by targeted high-throughput sequencing in a family with altered behavior and cognition.

Intellectual disability (ID) is characterized by an extraordinary genetic heterogeneity, with >250 genes that have been implicated in monogenic forms of ID. Because this complexity precluded systematic testing for mutations and because clinical features are often non-specific, for some of these genes only few cases or families have been unambiguously documented. It is the case of the X-linked gene encoding monoamine oxidase A (MAOA), for which only one nonsense mutation has been identified in Brunner syndrome, characterized in a single family by mild non-dysmorphic ID and impulsive, violent and aggressive behaviors. We have performed targeted high-throughput sequencing of 220 genes, including MAOA, in patients with undiagnosed ID. We identified a c.797_798delinsTT (p.C266F) missense mutation in MAOA in a boy with autism spectrum disorder, attention deficit and autoaggressive behavior. Two maternal uncles carry the mutation and have severe ID, with a history of maltreatment in early childhood. This novel missense mutation decreases MAOA enzymatic activity, leading to abnormal levels of urinary monoamines. The identification of this new point mutation confirms, for the first time since 1993, the monogenic implication of the MAOA gene in ID of various degrees, autism and behavioral disturbances. The variable expressivity of the mutation observed in male patients of this family may involve gene-environment interactions, and the identification of a perturbation in monoamine metabolism should be taken into account when prescribing psychoactive drugs in such patients.