Carrier Frequency (carrier + frequency)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


Carrier frequency of SMA by quantitative analysis of the SMN1 deletion in the Iranian population

EUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2010
M. Hasanzad
Background and purpose:, Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder. Carrier frequency studies of SMA have been reported for various populations. Although no large-scale population-based studies of SMA have been performed in Iran, previous estimates have indicated that the incidence of autosomal recessive disorder partly because of the high prevalence of consanguineous marriage is much higher in the Iranian population than in other populations. Methods:, In this study, we used a reliable and highly sensitive quantitative real-time PCR assay with SYBR green I dye to detect the copy number of the SMN1 gene to determine the carrier frequency of SMA in 200 healthy unrelated, non-consanguineous couples from different part of Iran. Results:, To validate the method in our samples, we determined the relative quantification (RQ) of patients with homozygous deletion (0.00) and hemyzygous carriers (0.29,0.55). The RQ in 10 of 200 normal individuals were within the carrier range of 0.31,0.57, estimating a carrier frequency of 5% in the Iranian population. Conclusions:, Our data show that the SMA carrier frequency in Iran is higher than in the European population and that further programs of population carrier detection and prenatal testing should be implemented. [source]


Parkinson's disease and LRRK2: Frequency of a common mutation in U.S. movement disorder clinics

MOVEMENT DISORDERS, Issue 4 2006
Denise M. Kay PhD
Abstract The G2019S mutation in the LRRK2 gene is reportedly a common cause of familial Parkinson's disease (PD) and may also have a significant role in nonfamilial PD. The objective of this study was to assess mutation carrier frequency in PD patients from movement disorder clinics in the United States, stratified by family history, age at onset, and geography; to determine carrier frequency in a large and well-characterized control population; to examine segregation of mutation in families of patients; and to correlate genotype with clinical phenotype. One thousand four hundred twenty-five unrelated PD patients from movement disorder clinics in Oregon, Washington, and New York and 1,647 unrelated controls were studied. The G2019S mutation was detected using a TaqMan assay and verified by sequencing. Eighteen of 1,425 patients and one of 1,647 controls had the mutation. Carrier frequency (± 2SE) in patients was 0.013 ± 0.006 overall, 0.030 ± 0.019 in familial PD, 0.007 ± 0.005 in nonfamilial PD, 0.016 ± 0.013 in early-onset PD, and 0.012 ± 0.007 in late-onset PD. Geographic differences were insignificant. Age at onset of mutation carriers ranged from 28 to 71 years. Mutation carriers were clinically indistinguishable from idiopathic PD. LRRK2 G2019S is the single most common pathogenic mutation linked to neurodegenerative disease to date. © 2005 Movement Disorder Society [source]


Enhancement of steady-state auditory evoked magnetic fields in tinnitus

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2004
Eugen Diesch
Abstract The steady-state auditory evoked magnetic field and the Pbm, the magnetic counterpart of the second frontocentrally positive middle latency component of the transitory auditory evoked potential, were measured in ten tinnitus patients using a 122-channel gradiometer system. The patients had varying degrees of hearing loss. In all patients, the tinnitus frequency was located above the frequency of the audiometric edge, i.e. the location on the frequency axis above which hearing loss increases more rapidly. Stimuli were amplitude-modulated sinusoids with carrier frequencies at the tinnitus frequency, the audiometric edge, two frequencies below the audiometric edge, and two frequencies between the audiometric edge and the tinnitus frequency. Below the audiometric edge, the root-mean-square field amplitude of the steady-state response computed across the whole head as well as the contralateral and the ipsilateral dipole moment decreased as a function of carrier frequency. With carrier frequency above the audiometric edge, the steady-state response increased again. The amplitudes of the transitory Pbm component were patterned in a qualitatively similar way, but without the differences being significant. For the steady-state response, both whole-head root-mean-square field amplitude and the dipole moment of the sources at the tinnitus frequency showed significant positive correlations with subjective ratings of tinnitus intensity and intrusiveness. These correlations remained significant when the influence of hearing loss was partialled out. The observed steady-state response amplitude pattern likely reflects an enhanced state of excitability of the frequency region in primary auditory cortex above the audiometric edge. The relationship of tinnitus to auditory cortex hyperexcitability and its independence of hearing loss is discussed with reference to loss of surround inhibition in and map reorganization of primary auditory cortex. [source]


No evidence for association of the TP53 12139 and the BAX,248 polymorphisms with endemic pemphigus foliaceus (fogo selvagem)

INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 2 2006
K. F. Köhler
Summary Pemphigus foliaceus (PF) is an autoimmune bullous epidermal disease, characterized by autoantibodies specific to the desmosomal protein desmoglein 1 (dsg1) and by acantholysis, the rupture of the cellular junctions among keratinocytes. Known also as fogo selvagem (wild fire) in Brazil, the disease has distinct epidemiological characteristics, being endemic in certain regions of South America. It is a multifactorial (complex) disease, with oligo- or polygenic disease susceptibility. In view of the previously reported evidences of a role for apoptosis dysregulation in pemphigus pathogenesis, we hypothesized that genetic variants of molecules participating in apoptosis may contribute to interindividual variation of susceptibility to PF. The TP53 12139(G,C) and the BAX,248(G,A) single nucleotide polymorphisms (SNP) were analysed in a genetic association study. The allelic, genotypic and allele carrier frequencies for these SNPs did not differ statistically between the patient and the control groups, for both the Euro- and the Afro-Brazilian population strata. The results of this study lead us to conclude that, although the TP53 and BAX alleles analysed differ functionally, this variation does not alter the functionality of the molecules in a way that would interfere with the development of the disease. [source]


Killer immunoglobulin-like receptor ligand HLA-Bw4 protects against multiple sclerosis,

ANNALS OF NEUROLOGY, Issue 6 2009
Åslaug R. Lorentzen MD
Objective Multiple sclerosis (MS) is a chronic inflammatory disease affecting the central nervous system. A human leukocyte antigen (HLA) class II association is well established (DRB1*1501-DQB1*0602), but more recently HLA class II,independent associations with HLA class I variants have also been reported. The HLA class I (HLA-A, -B, -C) molecules serve as ligands for both T-cell receptors and killer immunoglobulin-like receptors (KIRs). We investigated the HLA class I alleles defined by their KIR binding motifs and the KIR genes to evaluate whether these genes could influence MS susceptibility or severity, alone or in combination. Methods We typed Norwegian MS patients (n = 631) and controls (n = 555) for HLA-A, -B, -C and -DRB1 alleles as well as the presence or absence of genes encoding inhibitory (KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL5, KIR3DL1, KIR3DL2, KIR3DL3) and activating (KIR2DS1, KIR2DS2, KIR2DS3, KIR2DL4, KIR2DS4, KIR2DS5, KIR3DS1) KIRs. Results The frequency of the HLA-Bw4 specificity, which is the ligand for the inhibitory KIR3DL1, was significantly reduced in MS patients as compared with controls (41.4% vs 55.1%, puncorrected (uc) = 4.6 × 10,6). Also after stratifying for known HLA class II associations, the HLA-Bw4 association was seen (puc = 0.002). No significant differences in gene carrier frequencies of inhibitory and activating KIRs were observed. However, our data indicate that MS patients who carry the activating KIR2DS2 and the inhibitory KIR2DL2 genes have more severe disease than patients not carrying these genes. Interpretation Carriage of the ligand of the inhibitory KIR3DL1 receptor, HLA-Bw4, was found to protect against MS in an HLA-DRB1 independent manner. Ann Neurol 2009;65:658,666 [source]


Carrier frequency of SMA by quantitative analysis of the SMN1 deletion in the Iranian population

EUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2010
M. Hasanzad
Background and purpose:, Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder. Carrier frequency studies of SMA have been reported for various populations. Although no large-scale population-based studies of SMA have been performed in Iran, previous estimates have indicated that the incidence of autosomal recessive disorder partly because of the high prevalence of consanguineous marriage is much higher in the Iranian population than in other populations. Methods:, In this study, we used a reliable and highly sensitive quantitative real-time PCR assay with SYBR green I dye to detect the copy number of the SMN1 gene to determine the carrier frequency of SMA in 200 healthy unrelated, non-consanguineous couples from different part of Iran. Results:, To validate the method in our samples, we determined the relative quantification (RQ) of patients with homozygous deletion (0.00) and hemyzygous carriers (0.29,0.55). The RQ in 10 of 200 normal individuals were within the carrier range of 0.31,0.57, estimating a carrier frequency of 5% in the Iranian population. Conclusions:, Our data show that the SMA carrier frequency in Iran is higher than in the European population and that further programs of population carrier detection and prenatal testing should be implemented. [source]


Enhancement of steady-state auditory evoked magnetic fields in tinnitus

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2004
Eugen Diesch
Abstract The steady-state auditory evoked magnetic field and the Pbm, the magnetic counterpart of the second frontocentrally positive middle latency component of the transitory auditory evoked potential, were measured in ten tinnitus patients using a 122-channel gradiometer system. The patients had varying degrees of hearing loss. In all patients, the tinnitus frequency was located above the frequency of the audiometric edge, i.e. the location on the frequency axis above which hearing loss increases more rapidly. Stimuli were amplitude-modulated sinusoids with carrier frequencies at the tinnitus frequency, the audiometric edge, two frequencies below the audiometric edge, and two frequencies between the audiometric edge and the tinnitus frequency. Below the audiometric edge, the root-mean-square field amplitude of the steady-state response computed across the whole head as well as the contralateral and the ipsilateral dipole moment decreased as a function of carrier frequency. With carrier frequency above the audiometric edge, the steady-state response increased again. The amplitudes of the transitory Pbm component were patterned in a qualitatively similar way, but without the differences being significant. For the steady-state response, both whole-head root-mean-square field amplitude and the dipole moment of the sources at the tinnitus frequency showed significant positive correlations with subjective ratings of tinnitus intensity and intrusiveness. These correlations remained significant when the influence of hearing loss was partialled out. The observed steady-state response amplitude pattern likely reflects an enhanced state of excitability of the frequency region in primary auditory cortex above the audiometric edge. The relationship of tinnitus to auditory cortex hyperexcitability and its independence of hearing loss is discussed with reference to loss of surround inhibition in and map reorganization of primary auditory cortex. [source]


Array antenna assisted doppler spread compensator for OFDM

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2002
Minoru Okada
This paper proposes a novel array-antenna-assisted Doppler spread compensator for orthogonal frequency division multiplexing (OFDM), which is sensitive to fast time-variation of the radio propagation channel. In the proposed compensator, a linear array antenna is installed on top of the vehicle. The compensator estimates the received signal at a certain point on the linear array antenna by using space domain interpolation. Because the relative position of the estimated receiving point with respect to the ground does not change during the effective symbol duration of an OFDM signal, the time variation due to the movement of the vehicle can be compensated for. Computer simulation shows that the compensator can compensate for the bit error rate performance degradation due to time-variation of the channel when the velocity of the vehicle is up to 180km/h and a two-element array antenna is used at the carrier frequency of 600 MHz. The bit error rate performance can be further improved by using a four-element array antenna. [source]


Molecular diagnosis of inherited disorders: lessons from hemoglobinopathies,

HUMAN MUTATION, Issue 5 2005
George P. Patrinos
Abstract Hemoglobinopathies constitute a major health problem worldwide, with a high carrier frequency, particularly in certain regions where malaria has been endemic. These disorders are characterized by a vast clinical and hematological phenotypic heterogeneity. Over 1,200 different genetic alterations that affect the DNA sequence of the human ,-like (HBZ, HBA2, HBA1, and HBQ1) and ,-like (HBE1, HBG2, HBG1, HBD, and HBB) globin genes are mainly responsible for the observed clinical heterogeneity. These mutations, together with detailed information about the resulting phenotype, are documented in the globin locus-specific HbVar database. Family studies and comprehensive hematological analyses provide useful insights for accurately diagnosing thalassemia at the DNA level. For this purpose, numerous techniques can provide accurate, rapid, and cost-effective identification of the underlying genetic defect in affected individuals. The aim of this article is to review the diverse methodological and technical platforms available for the molecular diagnosis of inherited disorders, using thalassemia and hemoglobinopathies as a model. This article also attempts to shed light on issues closely related to thalassemia diagnostics, such as prenatal and preimplantation genetic diagnoses and genetic counseling, for better-quality disease management. Hum Mutat 26(5), 399,412, 2005. © 2005 Wiley-Liss, Inc. [source]


Germline mutations 657del5 of the NBS1 gene contribute significantly to the incidence of breast cancer in Central Poland

INTERNATIONAL JOURNAL OF CANCER, Issue 2 2006
Jan Steffen
Abstract Recent studies have demonstrated that heterozygous carriers of the NBS1 657del5 mutation have an increased risk for familial and bilateral breast cancer, but similar studies in consecutive breast cancer patients were inconclusive. Here, in a study of 562 nonselected breast cancer patients from Central Poland, we found 11 (1.96%) 657del5 mutation carriers vs. 3.47 expected (OR 3.21, 95%CI: 1.36,7.61, p = 0.0107) and only 9 (1.6%) carriers of the 5382insC mutation of the BRCA1 gene, most frequently found among breast cancer patients in Poland. No carriers of R215W, another pathogenic mutation of the NBS1 gene, were found in the present study. All carriers of the 657del5 mutation had sporadic breast tumors while 5 of 9 5382insC carriers had a family history of breast/ovarian cancer or bilateral breast carcinoma. In the pooled group of patients from the present and our previous study, carried out also in patients from Central Poland, we obtained the following risk estimates (OR) for 657del5 carriers, as related to the age at breast cancer diagnosis: <40 years: 8.36; (95%CI: 2.57,27.27) p = 0.0003; <50 years: 4.27 (95%CI: 1.67,10.89) p = 0.003; ,50 years: 2.40 (95%CI: 0.91,6.35) p = 0.1250; all ages: 3.13 (95% CI: 1.40,7.00) p = 0.0066. These findings demonstrate conclusively that NBS1 657del5 mutation carriers have a significantly, though moderately increased, age-related risk of breast cancer, and imply that in populations with a high 657del5 carrier frequency this mutation may contribute substantially to the overall incidence of breast cancer, particularly in younger age groups. © 2006 Wiley-Liss, Inc. [source]


An optimum design of deep-space downlinks affected by tropospheric attenuation,

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2009
Emilio Matricciani
Abstract In the paper, we propose an optimum design of deep-space downlinks made with 2 hops, at Ka band and above, in which each hop should be designed for providing half of the total noise-to-signal power ratio. We have derived this result from maximizing the ratio between the tropospheric attenuation in the 2-hop downlink and that in the 1-hop downlink. The design of the 1st hop (free-space) of the 2-hop downlink can reduce the spacecraft power, for the same antennas physical size, by increasing the carrier frequency from Ka band (32,GHz) to W band (80,GHz). This choice is not available in 1-hop downlink design because of the huge Earth tropospheric attenuation expected in the W frequency band. To show a practical design, we have applied the theory to compare 1-hop downlink design at 32,GHz to 2-hop downlink design that adopts 32 or 80,GHz in the 1st hop. The calculations refer to spacecrafts located at two astronomical units (300×106,km, about planet Mars) and to NASA and ESA receiving stations located in Goldstone (California), Cebreros (Madrid, Spain), Canberra and New Norcia (Australia). At 0.1% outage probability, in an average year or in the worst month, 1-hop downlinks show performance critical or close to fail, because of the large tropospheric attenuation (except at Goldstone), while 2-hop downlinks always work. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Scale effects and constraints for sound production in katydids (Orthoptera: Tettigoniidae): correlated evolution between morphology and signal parameters

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2009
F. MONTEALEGRE-Z
Abstract Male katydids (Orthoptera: Tettigoniidae) produce mating calls by rubbing the wings together, using specialized structures in their forewings (stridulatory file, scraper and mirror). A large proportion of species (ca. 66%) reported in the literature produces ultrasonic signals as principal output. Relationships among body size, generator structures and the acoustic parameters carrier frequency (fc) and pulse duration (pd), were studied in 58 tropical species that use pure-tone signals. A comparative analysis, based on the only available katydid phylogeny, shows how changes in sound generator form are related to changes in fc and pd. Anatomical changes of the sound generator that might have been selected via fc and pd are mirror size, file length and number of file teeth. Selection for structures of the stridulatory apparatus that enhance wing mechanics via file-teeth and scraper morphology was crucial in the evolution of ultrasonic signals in the family Tettigoniidae. [source]


A simple approach for phase-modulated single-scan 2D NMR spectroscopy

MAGNETIC RESONANCE IN CHEMISTRY, Issue 10 2005
Nikolas Salisbury Andersen
Abstract Conventional NMR spectroscopy techniques require long acquisition times due to the recovery time between the repeated excitations necessary for each increment of the evolution times in the indirectly detected dimensions. Here we outline a pulse sequence element for gradient-assisted ultrafast multidimensional NMR spectroscopy using frequency-modulated ,chirp' pulses to generate phase-modulated magnetization in an indirectly detected spectral dimension. The potential of this sequence element is demonstrated by acquiring a correlation spectroscopy (COSY) spectrum in 96 ms. This new pulse sequence element is an extension of ultrafast spectroscopy techniques based on the generation of amplitude modulation of the NMR signal in the indirectly detected spectral dimensions. The use of phase modulation instead of amplitude modulation helps broaden the applicability and may provide an increase of sensitivity in some experiments due to the ability to distinguish between positive and negative frequency offsets relative to the carrier frequency of the sequence element. Copyright © 2005 John Wiley & Sons, Ltd. [source]


X-band low phase noise in-phase and out-of-phase injection-locked push,push DRO

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2010
Zhou Cao
Abstract An X-band push,push dielectric resonator (DR) oscillator with injection locking capability has been developed. Two injection locking methods, i.e., the in-phase method and the out-of-phase method, are studied. It is found that the out-of-phase method has wider locking range and much less effects on fundamental suppression than that of the in-phase method. The oscillator generates an output power of 9.5 dBm at 12.4 GHz and has a fundamental suppression of 32.5 dBc. Despite using a high quality (Q) factor DR, wide locking range has been obtained. SiGe HBTs with good flicker noise performance were chosen for low phase noise design. The phase noise values of the free running oscillator are ,104.4 dBc/Hz, ,120.2 dBc/Hz, and ,142.6 dBc/Hz at 10 kHz, 100 kHz, and 1 MHz offsets from the carrier frequency, respectively. The phase noise performance is superior or comparable to the reported designs. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2448,2452, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25510 [source]


A low voltage balanced Clapp VCO in 0.13 micromolar CMOS technology

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2010
Sheng-Lyang Jang
Abstract A balanced voltage-controlled oscillator (VCO) is designed and implemented in a 0.13 ,m CMOS 1P8M process. The designed VCO circuit topology is an all nMOS LC-tank Clapp VCO using a series-tuned resonator. At the supply voltage of 0.5 V, the output phase noise of the VCO is ,108.69 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 17.72 GHz, and the figure of merit is ,186.84 dBc/Hz. The core power consumption is 4.2 mW. Tuning range is about 3.32 GHz, from 17.55 to 20.87 GHz, while the control voltage was tuned from 0 to 1.3 V. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1623,1625, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25275 [source]


Ka-band substrate integrated waveguide voltage-controlled Gunn oscillator

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2010
Zhou Cao
Abstract A Ka-band substrate integrated waveguide (SIW) voltage-controlled oscillator (VCO) is demonstrated using GaAs Gunn diode.GaAs hyperabrupt varactor is employed in parallel to the Gunn diode for low phase noise and wideband tuning. The VCO achieves a tuning range of more than 1 GHz by varying the varactor tuning voltage between 0 V and 9 V, and phase noise of ,102.1 dBc/Hz at 1 MHz offset from a 36 GHz carrier frequency. The output power varies from 9.3 dBm to 11.3 dBm within the tuning range. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1232,1235, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25169 [source]


SCM transmission in MM fiber with automatic selection of the subcarrier frequency

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2009
Marcin Kowalczyk
Abstract Demonstrated was a 10 Mbit/s binary frequency shift keying subcarrier multiplexing system operating beyond the pass-band of 1 km MM graded index optical fiber. The system automatically adjusted the carrier frequency to the fiber frequency response. Transmission of four 10 Mbit/s channels was also shown over the same fiber. No visible channel interaction was observed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1212,1214, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24277 [source]


Wideband MIMO measurements of outdoor NLOS channels

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2006
Yaoqing Yang
Abstract The measurement results of the wideband wireless multiple-input multiple-output (MIMO) channels in outdoor environments are presented. Our wideband wireless MIMO channel sounder consists of four transmitters and eight receivers, and operates at a carrier frequency of 1.8 GHz with a bandwidth of 2.5 MHz. After obtaining the multipath delay profiles from the data collected in non-line-of-sight (NLOS) environments, realistic wideband MIMO channel capacities are computed and compared with the ideal channel simulation. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 216,218, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21309 [source]


Parkinson's disease and LRRK2: Frequency of a common mutation in U.S. movement disorder clinics

MOVEMENT DISORDERS, Issue 4 2006
Denise M. Kay PhD
Abstract The G2019S mutation in the LRRK2 gene is reportedly a common cause of familial Parkinson's disease (PD) and may also have a significant role in nonfamilial PD. The objective of this study was to assess mutation carrier frequency in PD patients from movement disorder clinics in the United States, stratified by family history, age at onset, and geography; to determine carrier frequency in a large and well-characterized control population; to examine segregation of mutation in families of patients; and to correlate genotype with clinical phenotype. One thousand four hundred twenty-five unrelated PD patients from movement disorder clinics in Oregon, Washington, and New York and 1,647 unrelated controls were studied. The G2019S mutation was detected using a TaqMan assay and verified by sequencing. Eighteen of 1,425 patients and one of 1,647 controls had the mutation. Carrier frequency (± 2SE) in patients was 0.013 ± 0.006 overall, 0.030 ± 0.019 in familial PD, 0.007 ± 0.005 in nonfamilial PD, 0.016 ± 0.013 in early-onset PD, and 0.012 ± 0.007 in late-onset PD. Geographic differences were insignificant. Age at onset of mutation carriers ranged from 28 to 71 years. Mutation carriers were clinically indistinguishable from idiopathic PD. LRRK2 G2019S is the single most common pathogenic mutation linked to neurodegenerative disease to date. © 2005 Movement Disorder Society [source]


Preconceptional and prenatal screening for fragile X syndrome: Experience with 40 000 tests

PRENATAL DIAGNOSIS, Issue 11 2007
Michal Berkenstadt
Abstract Objectives To determine the carrier frequency of fragile X syndrome, and the rate of expansion from premutation (PM) carrier to full mutation (FM) fetus. Methods Results were analyzed on women with no family history of fragile X syndrome, or who were PM/FM carriers, who were tested between January 1994 and June 2004. PM was defined 55,199 repeats, FM above 200. Results Out of 40 079 women screened, 5 FM and 255 PM carriers were detected. There was no significant difference in carrier frequency between those with versus those without family history of mental retardation or developmental abnormalities: 1 in 128 (28/3596) versus 1 in 157 (232/36 483). However, the median of repeats differed significantly: 58 and 66 repeats, respectively, (P < 0.0001). Invasive prenatal diagnosis was carried out in 370 pregnancies (7 FM and 363 PM). Thirty FM fetuses were detected. There was a lower expansion rate in cases without a family history: 10% (17/169 PMs) compared to 50% (11/22 PMs) in those with a history, but this could be accounted for by the difference in allele size. Conclusion There is now sufficient information on screening parameters and prenatal diagnosis of fragile X syndrome to offer testing to women of reproductive age. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Frequency processing at consecutive levels in the auditory system of bush crickets (tettigoniidae)

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 15 2010
Tim Daniel Ostrowski
Abstract We asked how processing of male signals in the auditory pathway of the bush cricket Ancistrura nigrovittata (Phaneropterinae, Tettigoniidae) changes from the ear to the brain. From 37 sensory neurons in the crista acustica single elements (cells 8 or 9) have frequency tuning corresponding closely to the behavioral tuning of the females. Nevertheless, one-quarter of sensory neurons (approximately cells 9 to 18) excite the ascending neuron 1 (AN1), which is best tuned to the male's song carrier frequency. AN1 receives frequency-dependent inhibition, reducing sensitivity especially in the ultrasound. When recorded in the brain, AN1 shows slightly lower overall activity than when recorded in the prothoracic ganglion close to the spike-generating zone. This difference is significant in the ultrasonic range. The first identified local brain neuron in a bush cricket (LBN1) is described. Its dendrites overlap with some of AN1-terminations in the brain. Its frequency tuning and intensity dependence strongly suggest a direct postsynaptic connection to AN1. Spiking in LBN1 is only elicited after summation of excitatory postsynaptic potentials evoked by individual AN1-action potentials. This serves a filtering mechanism that reduces the sensitivity of LBN1 and also its responsiveness to ultrasound as compared to AN1. Consequently, spike latencies of LBN1 are long (>30 ms) despite its being a second-order interneuron. Additionally, LBN1 receives frequency-specific inhibition, most likely further reducing its responses to ultrasound. This demonstrates that frequency-specific inhibition is redundant in two directly connected interneurons on subsequent levels in the auditory system. J. Comp. Neurol. 518:3101,3116, 2010. © 2010 Wiley-Liss, Inc. [source]


Revisiting MSUD in Portuguese Gypsies: Evidence for a Founder Mutation and for a Mutational Hotspot within the BCKDHA Gene

ANNALS OF HUMAN GENETICS, Issue 3 2009
Sofia Quental
Summary Maple syrup urine disease (MSUD) is a rare autosomal recessive disorder of branched-chain amino acid metabolism. In the context of the wide mutational spectrum known for this disease, a few common mutations have been described in populations where founder effects played a major role in modeling diversities. In Portugal, for instance, a high proportion of patients are of Gypsy origin and all share the same mutation (c.117delC-,; p.R40GfsX23), causing the neonatal severe form of MSUD. In this study, we used four microsatellite markers closely flanking the BCKDHA gene (E1, protein) to demonstrate that c.117delC-, is a founder mutation responsible for the high incidence of the disorder among Portuguese Gypsies. These results are of medical relevance since carrier tests and prenatal diagnosis can be offered to families at risk, particularly because the carrier frequency of c.117delC-, was estimated at 1.4% among the healthy Portuguese Gypsies from the South of the country. Finally we present evidence that the genomic region of the BCKDHA gene where c.117delC-, is located is likely a mutational hotspot, since recurrence of c.117delC-, was observed in two distinct population groups. [source]


Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations and risk for pancreatic adenocarcinoma

CANCER, Issue 1 2010
Robert R. McWilliams MD
Abstract BACKGROUND: Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are common in white persons and are associated with pancreatic disease. The purpose of this case-control study was to determine whether CFTR mutations confer a higher risk of pancreatic cancer. METHODS: In a case-control study, the authors compared the rates of 39 common cystic fibrosis-associated CFTR mutations between 949 white patients with pancreatic adenocarcinoma and 13,340 white controls from a clinical laboratory database for prenatal testing for CFTR mutations. The main outcome measure was the CFTR mutation frequency in patients and controls. RESULTS: Overall, 50 (5.3%) of 949 patients with pancreatic cancer carried a common CFTR mutation versus 510 (3.8%) of 13,340 controls (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.04-1.89; P = .027). Among patients who were younger when their disease was diagnosed (<60 years), the carrier frequency was higher than in controls (OR, 1.82; 95% CI, 1.14-2.94; P = .011). In patient-only analyses, the presence of a mutation was associated with younger age (median 62 vs 67 years; P = .034). In subgroups, the difference was seen only among ever-smokers (60 vs 65 years, P = .028). Subsequent sequencing analysis of the CFTR gene detected 8 (16%) compound heterozygotes among the 50 patients initially detected to have 1 mutation. CONCLUSIONS: Carrying a disease-associated mutation in CFTR is associated with a modest increase in risk for pancreatic cancer. Those affected appear to be diagnosed at a younger age, especially among smokers. Clinical evidence of antecedent pancreatitis was uncommon among both carriers and noncarriers of CFTR mutations. Cancer 2010. © 2010 American Cancer Society. [source]