Confirmation of Clinical Diagnosis in Requests for Prenatal Prediction of SMA Type I

The recent discovery of a major SMA-locus in the chromosomal region 5q makes it possible to carry out prenatal DNA studies in families in which a child with SMA type I has been born. Since direct mutation analysis is not yet possible, the reliability of prenatal prediction of SMA type I usually depends on the certainty of the clinical diagnosis in the index patient. Sixteen requests were received for DNA studies in couples who had had a previous child with SMA type I. After re-evaluation, the performance of prenatal diagnosis was rejected in four cases. Among the other twelve families prenatal DNA analysis of chorion villus biopsies has been carried out in three families. In all three cases the fetus had inherited the high-risk haplotypes from both parents, and the parents chose to terminate the pregnancy. An illustration of the prenatal DNA studies in one family is given. The importance of confirmation of the diagnosis SMA type I before performing DNA studies is emphasised

Molecular prediction of disease risk and severity in a large Dutch Crohn's disease cohort

Item does not contain fulltextBACKGROUND: Crohn's disease and ulcerative colitis have a complex genetic background. We assessed the risk for both the development and severity of the disease by combining information from genetic variants associated with inflammatory bowel disease (IBD). METHODS: We studied 2804 patients (1684 with Crohn's disease and 1120 with ulcerative colitis) and 1350 controls from seven university hospitals. Details of the phenotype were available for 1600 patients with Crohn's disease and for 800 with ulcerative colitis. Genetic association for disease susceptibility was tested for the nucleotide-binding and oligomerisation domain 2 gene (NOD2), the IBD5 locus, the Drosophila discs large homologue 5 and autophagy-related 16-like 1 genes (DLG5 and ATG16L1) and the interleukin 23 receptor gene (IL23R). Interaction analysis was performed for Crohn's disease using the most associated single nucleotide polymorphism (SNP) for each locus. Odds ratios were calculated in an ordinal regression analysis with the number of risk alleles as an independent variable to analyse disease development and severity. RESULTS: Association with Crohn's disease was confirmed for NOD2, IBD5, DLG5, ATG16L1 and IL23R. Patients with Crohn's disease carry more risk alleles than controls (p = 3.85 x 10(-22)). Individuals carrying an increasing number of risk alleles have an increasing risk for Crohn's disease, consistent with an independent effects multiplicative model (trend analysis p = 4.25 x 10(-23)). Patients with Crohn's disease with a more severe disease course, operations or an age of onset below 40 years have more risk alleles compared to non-stricturing, non-penetrating behaviour (p = 0.0008), no operations (p = 0.02) or age of onset above 40 years (p = 0.028). CONCLUSION: Crohn's disease is a multigenic disorder. An increase in the number of risk alleles is associated with an increased risk for the development of Crohn's disease and with a more severe disease course. Combining information from the known common risk polymorphisms may enable clinicians to predict the course of Crohn's disease

SMN1 dosage analysis in spinal muscular atrophy from India

BACKGROUND: Spinal muscular atrophy (SMA) represents the second most common fatal autosomal recessive disorder after cystic fibrosis. Due to the high carrier frequency, the burden of this genetic disorder is very heavy in developing countries like India. As there is no cure or effective treatment, genetic counseling becomes very important in disease management. SMN1 dosage analysis results can be utilized for identifying carriers before offering prenatal diagnosis in the context of genetic counseling. METHODS: In the present study we analyzed the carrier status of parents and sibs of proven SMA patients. In addition, SMN1 copy number was determined in suspected SMA patients and parents of children with a clinical diagnosis of SMA. RESULTS: wenty nine DNA samples were analyzed by quantitative PCR to determine the number of SMN1 gene copies present, and 17 of these were found to have one SMN1 gene copy. The parents of confirmed SMA patients were found to be obligate carriers of the disease. Dosage analysis was useful in ruling out clinical suspicion of SMA in four patients. In a family with history of a deceased floppy infant and two abortions, both parents were found to be carriers of SMA and prenatal diagnosis could be offered in future pregnancies. CONCLUSION: SMN1 copy number analysis is an important parameter for identification of couples at risk for having a child affected with SMA and reduces unwarranted prenatal diagnosis for SMA. The dosage analysis is also useful for the counseling of clinically suspected SMA with a negative diagnostic SMA test

Maximising Synergy among Tropical Plant Systematists, Ecologists, and Evolutionary Biologists

Closer collaboration among ecologists, systematists, and evolutionary biologists working in tropical forests, centred on studies within long-term permanent plots, would be highly beneficial for their respective fields. With a key unifying theme of the importance of vouchered collection and precise identification of species, especially rare ones, we identify four priority areas where improving links between these communities could achieve significant progress in biodiversity and conservation science: (i) increasing the pace of species discovery; (ii) documenting species turnover across space and time; (iii) improving models of ecosystem change; and (iv) understanding the evolutionary assembly of communities and biomes

Different atrophy-hypertrophy transcription pathways in muscles affected by severe and mild spinal muscular atrophy

BACKGROUND: Spinal muscular atrophy (SMA) is a neurodegenerative disorder associated with mutations of the survival motor neuron gene SMN and is characterized by muscle weakness and atrophy caused by degeneration of spinal motor neurons. SMN has a role in neurons but its deficiency may have a direct effect on muscle tissue. METHODS: We applied microarray and quantitative real-time PCR to study at transcriptional level the effects of a defective SMN gene in skeletal muscles affected by the two forms of SMA: the most severe type I and the mild type III. RESULTS: The two forms of SMA generated distinct expression signatures: the SMA III muscle transcriptome is close to that found under normal conditions, whereas in SMA I there is strong alteration of gene expression. Genes implicated in signal transduction were up-regulated in SMA III whereas those of energy metabolism and muscle contraction were consistently down-regulated in SMA I. The expression pattern of gene networks involved in atrophy signaling was completed by qRT-PCR, showing that specific pathways are involved, namely IGF/PI3K/Akt, TNF-alpha/p38 MAPK and Ras/ERK pathways. CONCLUSION: Our study suggests a different picture of atrophy pathways in each of the two forms of SMA. In particular, p38 may be the regulator of protein synthesis in SMA I. The SMA III profile appears as the result of the concurrent presence of atrophic and hypertrophic fibers. This more favorable condition might be due to the over-expression of MTOR that, given its role in the activation of protein synthesis, could lead to compensatory hypertrophy in SMA III muscle fibers

Evolutionary Heritage Influences Amazon Tree Ecology

Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change

Evolutionary Heritage Influences Amazon Tree Ecology

Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change

Fast demographic traits promote high diversification rates of Amazonian trees.

The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits ? short turnover times ? are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rates are either constant or decline over time, and occurs in a wide range of Neotropical tree lineages. This finding reveals the crucial role of intrinsic, ecological variation among clades for understanding the origin of the remarkable diversity of Amazonian trees and forests