Mutations in NALCN Cause an Autosomal-Recessive Syndrome with Severe Hypotonia, Speech Impairment, and Cognitive Delay

Sodium leak channel, nonselective (NALCN) is a voltage-independent and cation-nonselective channel that is mainly responsible for the leaky sodium transport across neuronal membranes and controls neuronal excitability. Although NALCN variants have been conflictingly reported to be in linkage disequilibrium with schizophrenia and bipolar disorder, to our knowledge, no mutations have been reported to date for any inherited disorders. Using linkage, SNP-based homozygosity mapping, targeted sequencing, and confirmatory exome sequencing, we identified two mutations, one missense and one nonsense, in NALCN in two unrelated families. The mutations cause an autosomal-recessive syndrome characterized by subtle facial dysmorphism, variable degrees of hypotonia, speech impairment, chronic constipation, and intellectual disability. Furthermore, one of the families pursued preimplantation genetic diagnosis on the basis of the results from this study, and the mother recently delivered healthy twins, a boy and a girl, with no symptoms of hypotonia, which was present in all the affected children at birth. Hence, the two families we describe here represent instances of loss of function in human NALCN

Multi-domain impact of elosufase alfa in Morquio A syndrome in the pivotal phase III trial

Objective: To report and discuss the multi-domain impact of elosulfase alfa, with focus on tertiary and composite endpoints, in the 24-week, randomized, double-blind, placebo-controlled phase 3 trial in patients with Morquio A syndrome (mucopolysaccharidosis IVA). Methods: Patients with Morquio A syndrome >= 5 aged years were randomized 1:1:1 to elosulfase alfa 2.0 mg/kg/week (qw; N = 58), elosulfase alfa 2.0 mg/kg/every other week (qow; N = 59), or placebo (N = 59) for 24 weeks. Primary and secondary efficacy measures were 6-minute walk test (6MWT; primary), 3-minute stair climb test (3-MSCT) and urinary keratan sulfate (KS). Safety was also evaluated. Tertiary efficacy measures included respiratory function measures, activities of daily living (MPS Health Assessment Questionnaire [MPS-HAQ]), anthropometric, echocardiographic and radiographic measures, hearing and corneal clouding assessment. In order to fully characterize treatment impact in this heterogeneous disorder, the effect of elosulfase alfa on composite efficacy measures was evaluated as well. Results: The study was not designed to have sufficient power for any of the tertiary outcomes. For most tertiary endpoints, subjects treated with the weekly dose of elosulfase alfa improved more than those receiving placebo. The largest treatment effects were seen in maximal voluntary ventilation (MVV), MPS-HAQ height, and growth rate. The qow group appeared similar to placebo. The analysis of a pre-specified composite endpoint (combining changes from baseline in 6MWT, 3MSCT and MW z-scores equally weighted) showed a modest positive impact of elosulfase alfa qw versus placebo group (P = 0.053). As a pre-specified supportive analysis, the O'Brien Rank Sum composite endpoint (changes from baseline in 6MWT, 3MSC, and MW), analysis also showed that the qw group performed better than the placebo group (P = 0.011). In post-hoc analyses, combinations of other endpoints were also explored using the O'Brien Rank Sum test and showed statistically significant differences between elosulfase alfa qw and placebo favoring elosulfase alfa qw. Differences between elosulfase alfa qow and placebo were not statistically significant. Positive changes were observed in most tertiary variables, demonstrating the efficacy of weekly treatment with elosulfase alfa. Conclusions: Treatment with weekly elosulfase alfa led to improvements across most efficacy measures, resulting in clinically meaningful benefits in a heterogeneous study population. (C) 2014 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/