Genes Encoding Ion Channels Research Articles

Linkage Evidence for a Two-Locus Inheritance of LQT-Associated Seizures in a Multigenerational LQT Family With a Novel KCNQ1 Loss-of-Function Mutation.

Mutations in several genes encoding ion channels can cause the long-QT (LQT) syndrome with cardiac arrhythmias, syncope and sudden death. Recently, mutations in some of these genes were also identified to cause epileptic seizures in these patients, and the sudden unexplained death in epilepsy (SUDEP) was considered to be the pathologic overlap between the two clinical conditions. For LQT-associated KCNQ1 mutations, only few investigations reported the coincidence of cardiac dysfunction and epileptic seizures. Clinical, electrophysiological and genetic characterization of a large pedigree (n = 241 family members) with LQT syndrome caused by a 12-base-pair duplication in exon 8 of the KCNQ1 gene duplicating four amino acids in the carboxyterminal KCNQ1 domain (KCNQ1dup12; p.R360_Q361dupQKQR, NM_000218.2, hg19). Electrophysiological recordings revealed no substantial KCNQ1-like currents. The mutation did not exhibit a dominant negative effect on wild-type KCNQ1 channel function. Most likely, the mutant protein was not functionally expressed and thus not incorporated into a heteromeric channel tetramer. Many LQT family members suffered from syncopes or developed sudden death, often after physical activity. Of 26 family members with LQT, seizures were present in 14 (LQTplus seizure trait). Molecular genetic analyses confirmed a causative role of the novel KCNQ1dup12 mutation for the LQT trait and revealed a strong link also with the LQTplus seizure trait. Genome-wide parametric multipoint linkage analyses identified a second strong genetic modifier locus for the LQTplus seizure trait in the chromosomal region 10p14. The linkage results suggest a two-locus inheritance model for the LQTplus seizure trait in which both the KCNQ1dup12 mutation and the 10p14 risk haplotype are necessary for the occurrence of LQT-associated seizures. The data strongly support emerging concepts that KCNQ1 mutations may increase the risk of epilepsy, but additional genetic modifiers are necessary for the clinical manifestation of epileptic seizures.

The ion channels and transporters gene expression profile indicates a shift in excitability and metabolisms during malignant progression of Follicular Lymphoma

The definition of the gene expression profile of genes encoding Ion Channels and Transporters (ICT-GEP) represents a novel and attracting aspect in cancer. We determined the ICT-GEP of Follicular Lymphoma (FL), and compared it with that of the more aggressive Diffuse Large B Cell Lymphoma (DLBCL). cDNA microarray data were collected both from patients enrolled for this study, and from public datasets. In FL the ICT-GEP indicated the overexpression of both the K+ channel encoding gene KCNN4, and SLC2A1, which encodes the Glut1 glucose transporter. SLC2A1 turned out to represent the hub of a functional network, connecting channels and transporters in FL. Relapsed FL patients were characterised by 38 differentially expressed ICT genes, among which ATP9A, SLC2A1 and KCNN4 were under-expressed, indicating a down-regulation of both excitability and glycolysis. A completely different profile of K+ channel encoding genes emerged in DLBCL accompanied by the over-expression of the fatty acid transporter-encoding gene SLC27A1 as well as of the metabolism regulator NCoR1. This indicates a change in excitability and a shift towards an oxidative metabolism in DLBCL. Overall, the ICT-GEP may contribute to identifying novel lymphoma biomarkers related to excitability and metabolic pathways, with particular relevance for drug resistant, relapsed FL.

Genome-wide association study identifies 30 loci associated with bipolar disorder.

Bipolar disorder is a highly heritable psychiatric disorder. We performed a genome-wide association study including 20,352 cases and 31,358 controls of European descent, with follow-up analysis of 822 variants with P<1×10−4 in an additional 9,412 cases and 137,760 controls. Eight of the 19 variants that were genome-wide significant (GWS, p < 5×10−8) in the discovery GWAS were not GWS in the combined analysis, consistent with small effect sizes and limited power but also with genetic heterogeneity. In the combined analysis 30 loci were GWS including 20 novel loci. The significant loci contain genes encoding ion channels, neurotransmitter transporters and synaptic components. Pathway analysis revealed nine significantly enriched gene-sets including regulation of insulin secretion and endocannabinoid signaling. BDI is strongly genetically correlated with schizophrenia, driven by psychosis, whereas BDII is more strongly correlated with major depressive disorder. These findings address key clinical questions and provide potential new biological mechanisms for BD.

Heritability in genetic heart disease: the role of genetic background

BackgroundMutations in genes encoding ion channels or sarcomeric proteins are an important cause of hereditary cardiac disease. However, the severity of the resultant disease varies considerably even among those with...

Inwardly Rectifying Potassium Channels in Neurological Diseases in Last Decade

Along the last decade, the central role of ion channels in neurological diseases has been carefully studying. Especially, inwardly-rectifying potassium (Kir) channels controlling the cell excitability by acting towards the hyperpolarization phase of neuronal action potential are vital in the neurological disease mechanism. Recent functional studies have shown that the Kir channels associating with various neurological disorders, primarily epilepsy cannot carry K+ ions into the cell due to dysfunction. Investigations into the role of Kir channels with 7 subfamilies in the mechanism of neurological disorders (epilepsy, multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, autism, etc.) have shown that the Kir channels functionally may change. After the key role of Kir channels in the pathophysiology is shown, novel drug studies targeting these channels have begun to be developed. Mutations in genes encoding ion channel protein dysfunction have also been included in this review. This is the review to our knowledge in neurological disorders showing the functional expression of Kir channels. Our review shows that Kir channels may play a role in pathophysiology associated with neurologic diseases. In review, the role of Kir channels in various common neurological diseases will be classified and a resource will be created for the researchers

Glatiramer Acetate modulates ion channels expression and calcium homeostasis in B cell of patients with relapsing-remitting multiple sclerosis

To investigate the effects of Glatiramer Acetate (GA) on B cells by an integrated computational and experimental approach. GA is an immunomodulatory drug approved for the treatment of multiple sclerosis (MS). GA effect on B cells is yet to be fully elucidated. We compared transcriptional profiles of B cells from treatment-naïve relapsing remitting MS patients, treated or not with GA for 6 hours in vitro, and of B cells before and after six months of GA administration in vivo. Microarrays were analyzed with two different computational approaches, one for functional analysis of pathways (Gene Set Enrichment Analysis) and one for the identification of new drug targets (Mode-of-action by Network Analysis). GA modulates the expression of genes involved in immune response and apoptosis. A differential expression of genes encoding ion channels, mostly regulating Ca2+ homeostasis in endoplasmic reticulum (ER) was also observed. Microfluorimetric analysis confirmed this finding, showing a specific GA effect on ER Ca2+ concentration. Our findings unveils a GA regulatory effect on the immune response by influencing B cell phenotype and function. In particular, our results highlight a new functional role for GA in modulating Ca2+ homeostasis in these cells.

Timeline of Advances in Genetics of Primary Aldosteronism.

The overwhelming majority of cases of primary aldosteronism (PA) occur sporadically due to a unilateral aldosterone-producing adenoma (APA) or bilateral idiopathic adrenal hyperplasia. Familial forms of PA are rare with four subtypes defined to date (familial hyperaldosteronism types I-IV). The molecular basis of familial hyperaldosteronism type I (FH type I or glucocorticoid-remediable aldosteronism) was established in 1992; two decades later the genetic variant causing FH type III was identified and germline mutations causing FH type IV and FH type II were determined soon after. Effective diagnostic protocols and methods to detect the overactive gland in unilateral PA by adrenal venous sampling followed by laparoscopic adrenalectomy have made available APAs for scientific studies. In rapid succession, following the widespread use of next-generation sequencing, recurrent somatic driver mutations in APAs were identified in genes encoding ion channels and transporters. The development of highly specific monoclonal antibodies against key enzymes in adrenal steroidogenesis has unveiled the heterogeneous features of the diseased adrenal in PA and helped reveal the high proportion of APAs with driver mutations. We discuss what is known about the genetics of PA that has led to a clearer understanding of the disease pathophysiology.

Macrophages facilitate post myocardial infarction arrhythmias: roles of gap junction and KCa3.1.

Effective therapeutic targets against post-myocardial infarction (MI) arrhythmias remain to be discovered. We aimed to investigate the role of macrophages in post-MI arrhythmias.Methods: Mononuclear cell accumulation, macrophage polarization from M0 to M1 subset, and gap junction formation were analyzed in MI patients and MI mice by flow cytometry, immunofluorescence and patch clamping. Differentially expressed genes were identified by RNA sequencing. Macrophages and cardiomyocytes were cocultured in vitro, and the effects of gap junction and KCa3.1 on electrophysiological properties were assessed by patch clamping. The effects of KCa3.1 inhibition on post-MI arrhythmias were assessed by intracardiac stimulation and ambulatory electrocardiograms in vivo.Results: Percentage of pro-inflammatory mononuclear cells were significantly elevated in patients with post-MI arrhythmias compared with MI patients without arrhythmias and healthy controls (p<0.001). Macrophages formed gap junction with cardiomyocytes in MI border zones of MI patient and mice, and pro-inflammatory macrophages were significantly increased 3 days post-MI (p<0.001). RNA sequencing identified Kcnn4 as the most differentially expressed gene encoding ion channel, and the upregulation is mainly attributed to macrophage accumulation and polarization into pro-inflammatory subset. In vitro coculture experiments demonstrated that connection with M0 macrophages via gap junction slightly shortened the action potential durations (APDs) of cardiomyocytes. However, the APD90 of cardiomyocytes connected with M1 macrophages were significantly prolonged (p<0.001), which were effectively attenuated by gap junction inhibition (p=0.002), KCa3.1 inhibition (p=0.008), KCa3.1 silencing (p<0.001) and store-operated Ca2+ channel inhibition (p=0.005). In vivo results demonstrated that KCa3.1 inhibition significantly decreased the QTc durations (p=0.031), intracardiac stimulation-induced ventricular arrhythmia durations (p=0.050) and incidence of premature ventricular contractions (p=0.030) in MI mice.Conclusion: Macrophage polarization leads to APD heterogeneity and post-MI arrhythmias via gap junction and KCa3.1 activation. The results provide evidences of a novel mechanism of post-MI heterogeneous repolarization and arrhythmias, rendering macrophages and KCa3.1 to be potential therapeutic targets.

Calcium Channelopathies: Structural Insights into Disorders of the Muscle Excitation-Contraction Complex.

Ion channels are membrane proteins responsible for the passage of ions down their electrochemical gradients and across biological membranes. In this, they generate and shape action potentials and provide secondary messengers for various signaling pathways. They are often part of larger complexes containing auxiliary subunits and regulatory proteins. Channelopathies arise from mutations in the genes encoding ion channels or their associated proteins. Recent advances in cryo-electron microscopy have resulted in an explosion of ion channel structures in multiple states, generating a wealth of new information on channelopathies. Disease-associated mutations fall into different categories, interfering with ion permeation, protein folding, voltage sensing, ligand and protein binding, and allosteric modulation of channel gating. Prime examples of these are Ca2+-selective channels expressed in myocytes, for which multiple structures in distinct conformational states have recently been uncovered. We discuss the latest insights into these calcium channelopathies from a structural viewpoint.

Molecular autopsy in a cohort of infants died suddenly at rest

Sudden infant death syndrome is the leading cause of death during the first year of life. A large part of cases remains without a conclusive cause of death after complete autopsy. In these situations, cardiac arrhythmia of genetic origin is suspected as the most plausible cause of death. Our aim was to ascertain whether genetic variants associated with sudden cardiac death might be the cause of death in a cohort of infants died suddenly. We analyzed 108 genes associated with sudden cardiac death in 44 post-mortem samples of infants less than 1 year old of age who died at rest. Definite cause of death was not conclusive in any case after a complete autopsy. Genetic analysis identified at least one rare variant in 90.90% of samples. A total of 121 rare genetic variants were identified. Of them, 33.05% were novel and 39.66% were located in genes encoding ion channels or associated proteins. A comprehensive genetic analysis in infants who died suddenly enables the unraveling of potentially causative cardiac variants in 2045% of cases. Molecular autopsy should be included in forensic protocols when no conclusive cause of death is identified. Large part genetic variants remain of uncertain significance, reinforcing the crucial role of genetic interpretation before clinical translation but also in early identification of relatives at risk.

The transcriptome of the rat subfornical organ is altered in response to early postnatal overnutrition

Early postnatal overnutrition in humans is associated with long-term negative outcomes including obesity, increased risk of type-II diabetes, and cardiovascular disease. Hypothalamic neurons from rodents exposed to early postnatal overnutrition show altered expression of satiety signals and receptors, and exhibit altered responses to many satiety signals, suggesting a hypothalamic link between early overnutrition and development of these sequelae. Importantly, several hypothalamic nuclei receive information regarding circulating hormones (such as insulin, leptin and ghrelin) from the subfornical organ (SFO), a forebrain sensory circumventricular organ which lacks a blood brain barrier. Previous transcriptomic studies indicate that challenges to energy balance and hydration status stimulate changes in gene expression within the SFO, including genes encoding ion channels and receptors. In order to determine if early postnatal overnutrition also causes changes in SFO gene expression which may be associated with homeostatic dysregulation, we performed whole transcriptome sequencing on SFO tissue from rats raised in small (4 pups), or control (large, 12 pups) litters. Illumina RNA sequencing was performed on SFO tissue from rats raised from small and large litters, and read sequences were aligned to the Rat Rnor_6.0 genome. Control data were further compared to previously published microarray data set for validation. We found statistically significant (p<0.05) changes in expression of 12 transcripts, three of which have likely roles in neuronal excitability, neurite outgrowth and differentiation, and food intake (Manf, Slc24a4, Cracr2b). Additionally, gene ontology analysis identified a trend among significantly altered transcripts in roles for oxidative stress response. We conclude that the SFO transcriptome is subtly altered by early postnatal overnutrition, and recommend further investigation of the effect of early postnatal overnutrition on SFO physiology and morphology.

Autism throughout genetics: Perusal of the implication of ion channels.

BackgroundAutism spectrum disorder (ASD) comprises a group of neurodevelopmental psychiatric disorders characterized by deficits in social interactions, interpersonal communication, repetitive and stereotyped behaviors and may be associated with intellectual disabilities. The description of ASD as a synaptopathology highlights the importance of the synapse and the implication of ion channels in the etiology of these disorders.MethodsA narrative and critical review of the relevant papers from 1982 to 2017 known by the authors was conducted.ResultsGenome‐wide linkages, association studies, and genetic analyses of patients with ASD have led to the identification of several candidate genes and mutations linked to ASD. Many of the candidate genes encode for proteins involved in neuronal development and regulation of synaptic function including ion channels and actors implicated in synapse formation. The involvement of ion channels in ASD is of great interest as they represent attractive therapeutic targets. In agreement with this view, recent findings have shown that drugs modulating ion channel function are effective for the treatment of certain types of patients with ASD.ConclusionThis review describes the genetic aspects of ASD with a focus on genes encoding ion channels and highlights the therapeutic implications of ion channels in the treatment of ASD.

Implications of HSP 90 Q488H Polymorphism in Long QT Syndrome—A South Indian Study

Long QT syndrome (LQTS) is a rare primary cardiac electrophysiological disorder with characteristic symptoms of syncope, tachyarrhythmia and torsades-de-pointes. It is the outcome of mutations in genes encoding ion channels that function as voltage regulators. Heat shock protein (HSP) 90 is a molecular chaperone that plays vital roles in a variety of cellular processes, one of which is folding of nascent polypeptide chains into their native forms. The main objective of this study was to screen for HSP90 Q488H (C > G) polymorphism in patients with LQTS and identify its risk towards LQTS manifestation.

Expansions of intronic TTTCA and TTTTA repeats in benign adult familial myoclonic epilepsy

Epilepsy is a common neurological disorder, and mutations in genes encoding ion channels or neurotransmitter receptors are frequent causes of monogenic forms of epilepsy. Here we show that abnormal expansions of TTTCA and TTTTA repeats in intron 4 of SAMD12 cause benign adult familial myoclonic epilepsy (BAFME). Single-molecule, real-time sequencing of BAC clones and nanopore sequencing of genomic DNA identified two repeat configurations in SAMD12. Intriguingly, in two families with a clinical diagnosis of BAFME in which no repeat expansions in SAMD12 were observed, we identified similar expansions of TTTCA and TTTTA repeats in introns of TNRC6A and RAPGEF2, indicating that expansions of the same repeat motifs are involved in the pathogenesis of BAFME regardless of the genes in which the expanded repeats are located. This discovery that expansions of noncoding repeats lead to neuronal dysfunction responsible for myoclonic tremor and epilepsy extends the understanding of diseases with such repeat expansion.

Chapter 45 - Thermoregulation in epilepsy

Several aspects of thermoregulation play a role in epilepsy. Circuitries involved in thermoregulation are affected by seizures and epilepsy, hyperthermia may be both cause and result of seizures, and hypothermia may prevent or abort seizures. Autonomic manifestations of seizures including thermoregulatory disturbances are common in a variety of clinical epilepsy syndromes. Experimental hyperthermia has been studied extensively, predominantly to investigate febrile seizures of childhood. In particular prolonged or complex febrile seizures have been associated with the later development of epilepsy in adulthood and the pathophysiology of how febrile seizures cause epilepsy is of tremendous interest. Febrile seizures represent an opportunity to potentially intervene early in life in susceptible individuals and affect epileptogenesis. The pathophysiologic underpinnings of how hyperthermia induces seizures and how this in turn results in epilepsy are controversial, but likely involve multiple factors. Both glutamatergic and GABAergic neurotransmission is affected, and numerous mutations in genes encoding ion channels have been identified. Cytokines such as interleukin-1β have been implicated in febrile seizures as well as susceptibility to provoked seizures later in life. Hyperthermia is a common feature of generalized convulsive status epilepticus, but may also be seen with nonconvulsive seizures, indicating involvement of thermoregulatory centers.

Recent Progress in Identifying Genetic and Epigenetic Contributions to Epilepsy

Epilepsy is a serious disorder of the central nervous system characterized by recurrent seizures. There are many known causes of epilepsy, including genetic factors, brain damage, and environmental factors, but the pathogenic mechanisms are largely unknown. Numerous factors, including genetic mutations, brain damage, and environmental insults, have been implicated in the etiology of epilepsy, but the cause for individual epilepsy patients is often unknown. Research on inherited forms of epilepsy has identified mutations in genes encoding ion channels or neurotransmitter receptors. Family-based studies of inherited forms of epilepsy have previously identified mutations in genes encoding ion channels and neurotransmitter receptors. With a deepening understanding of the underlying cellular pathways, researchers have identified epilepsy candidate genes that function in synaptic vesicle trafficking, chromatin remodeling, transcription, and mammalian target of rapamycin (mTOR) signaling. More recently, genes involved in synaptic vesicle transport, chromatin remodeling, and transcription, as well as the mTOR signaling pathway, have also been implicated in inherited forms of the disorder. In addition, recent advances in DNA sequencing and genomic technologies have identified chromosomal copy number variants and epigenetic modifications as possible contributing factors in inherited epilepsy. In this review, we focus on the established and potential contributions of genes, chromosomal abnormalities, and epigenetic modifications to the development of epilepsy.

P.293 - Classic congenital myopathy with recessive mutations in genes encoding ion channels: clinical phenotype and good response to acetazolamide

We present data on 2 children with congenital myopathy due to mutations in genes encoding ion-channels. First, is a 10-year-old boy with neonatal hypotonia with lower limb contractures, bulbar and facial weakness, ophthalmoplegia, ptosis with maximal functional ability to sit independently. He uses NIV since the age of 7. He has periodic short-lived episodes where he loses head-control, develops slurred speech but remains conscious. Triggers include rest, hot weather, fasting, and illness. Exercise testing and CK were normal. Muscle MRI and biopsy showed changes compatible with congenital myopathy. Compound heterozygous mutations (p.Q1265H & p.E100K) were identified in CACNA1S gene using whole exome sequencing. p.E100K in isolation would predict a periodic paralysis phenotype. With acetazolamide, his periodic symptoms completely resolved and he gained some overall muscle strength over 1 year. Second, is a 16-year-old girl with neonatal-onset hypotonia, facial, axial and proximal weakness, hip, knee and ankle contractures with respiratory and feeding difficulties. She has ophthalmoplegia and uses NIV since the age of 6 and needed scoliosis surgery at 13. From the age of 12, she describes marked diurnal fluctuation in strength with short-lived episodic weakness during febrile illnesses, exertion and on hot days. She has significant fatigability. CK, stimulation SFEMG and exercise test were normal. Muscle biopsy and muscle MRI showed features of congenital myopathy. Compound heterozygous mutations were identified in SCN4A using whole exome sequencing. p.R1135C is reported previously with periodic paralysis. Treatment with salbutamol reduced fatigue. With acetazolamide, her periodic weakness and fluctuation in symptoms significantly improved. This report demonstrates the role of genetic evaluation in ion-channel related congenital myopathies. Mutations in specific regions of the channel may predict fluctuant symptoms and can help identify those who could be offered acetazolamide. These conditions present a diagnostic challenge as classical congenital myopathy mimics.

Analysis of gene mutation and clinical characteristics in patients with idiopathic epilepsy

Objective: To explore the association between gene mutations and clinical characteristics in Chinese patients with epilepsy. Methods: A total of twenty-three patients with idiopathic epilepsy admitted to the Xuanwu Hospital of Capital Medical University from January 2014 to July 2016 were included.The age at onset of epilepsy ranged from 8 months to 31 years.All patients were screened for mutations by next-generation of sequencing (NGS), using a targeted capture panel of epilepsy and related seizures to screen forgene causative for or related to epilepsy.Some mutations were verified for inheritance by Sanger sequencing of two generations in the family.The differences in clinical characteristics among different mutation carriers were compared. Results: A total of 38 mutations were identified in 23 patients.Most of the patients presented with tonic-clonic seizures, and most were not accompanied by mental retardation.Causative genes were dominated by those encoding ion channel, enzyme and proteins with special functions.Although mutation carriers for genes encoding ion channel proteins and those with special functions were not significantly different in age at onset, types of seizure, family history or complications(P>0.05), patients presenting with tonic-clonic seizures had higher frequency of mutations in genes encoding ion channel (15/15)than those encoding proteins with special function(16/20)(P=0.066). Conclusions: NGS is a useful technology in detecting mutations in patients with various types of epilepsy and aiding in etiological diagnosis of the disease.Tonic-clonic seizures may correlate with mutations in genes encoding ion channel.

Association of clinical severity of cystic fibrosis with variants in the SLC gene family (SLC6A14, SLC26A9, SLC11A1 and SLC9A3)

IntroductionCystic fibrosis (CF) manifests with clinical and histopathological variability depending on environmental and genetic factors. Moreover, the genes encoding ion channels[rs3788766(SLC6A14), rs7512462(SLC26A9), rs17235416(SLC11A1) and rs17563161(SLC9A3)] have been insufficiently studied as modifier genes. Then, our objective was associate the variants in the genes of SLC family with 43 CF severity markers. MethodsThe variants were identified by real-time-PCR in 188 CF patients considering the CFTR genotype. Statistical analyses were performed by parametric and nonparametric tests. The correction by multiple testing was performed by the False Rate Discovery test, alpha=0.05. ResultsDepending on the CFTR mutations, we found association of: (i) rs3788766*CC with mucoid Pseudomonas aeruginosa (OR=0.171; 95%CI=0.029–0.696), non-mucoid P. aeruginosa (OR=0.283; 95%CI=0.094–0.853) and Staphyloccocus aureus (OR=4.443; 95%CI=1.019–40.64), largest FEFmax(p=0.041) and best response to bronchodilator for FEF50%(p=0.033) and FEV1/FVC(p=0.044); (ii) rs3788766*CT with early start of pulmonary symptom (OR=3.524; 95%CI=1.229–10.1) and osteoporosis (OR=0.203; 95%CI=0.022–0.883); (iii) rs3788766*TT with lowest body mass index (OR=4.242; 95%CI=1.505–11.95), presence of mucoid P. aeruginosa (OR=3.176; 95%CI=1.29–7.819) and S. aureus (OR=0.116; 95%CI=0.004–0.881), highest Bhalla score (p=0.047) and lowest FEFmax(p=0.028) and FEF25%(p=0.031) values; (iv) rs7512462*CC with highest Shwachman-Kulczycki score (p=0.019), FVC(p=0.043), FEV1(p=0.047), FEV1/FVC(p=0.022), FEF50%(p=0.038) and FEF25–75%(p=0.016); (v) rs7512462*CT with lowest values of FVC(p=0.034), FEV1(p=0.047), FEV1/FVC(p=0.022), FEF25%(p=0.012), FEF50%(p=0.038), FEF75%(p=0.008), FEF25–75%(p=0.016) and ERV(p=0.023); (vi) rs7512462*TT with best response to the inhaled bronchodilator for FEV1(p=0.011), FEF50%(p=0.019), FEF75%(p=0.036) and FEF25–75%(p=0.008); (vii) rs17234516*Normal allele with lowest value of SaO2 (p=0.010) and S. aureus (OR=3.333; 95%CI=1.085–10.24); (viii) rs17563161*GG with lowest age for onset of digestive symptoms (OR=2.564; 95%CI=1.234–5.33). ConclusionsThe clinical and laboratory variability of CF were associated with the variants in the genes of SLC family in our sample.

Finding genes and lineages under selection in speciation.

What are the genes and traits that respond to selection and cause prezygotic reproductive isolation between species? This question has been hard to answer because genomes are large, the targets of selection may be scattered across the genome (Sabeti etal., ) and different genes may respond to the same selective pressure in different populations (Scheinfeldt etal., ). In this issue of Molecular Ecology, Weber etal. () use a clever comparative approach and leading-edge transcriptomic methods to identify the species and genes under positive selection for divergence between brittle stars (the echinoderm class Ophiuroidea) in the Ophioderma longicauda species complex. They found convincing evidence of positive or diversifying selection acting on two genes encoding ion channels that form part of the signal transduction cascade within the sperm in response to pheromones. Evidence for selection was concentrated in genes from one species (called C5, with internal fertilization and female parental care of brooded juveniles and not in the other species (called C3, with more conventional broadcast spawning and planktonic development of embryos and larvae). That analysis greatly extends the range of taxa, life history traits and molecules that are associated with positive selection in speciation. It also illustrates some of the current limitations on the application of RNAseq methods in the search for the targets of selection in nonmodel organisms like brittle stars. From both points of view, the new work by Weber etal. () has important implications for our understanding of speciation in the ocean.