Plasmodium falciparum causes the most severe form of malaria and kills up to 2.7 million people annually. Despite the global importance of P. falciparum, the vast majority of its proteins have not been characterized experimentally. Here we identify P. falciparum protein-protein interactions using a high-throughput version of the yeast two-hybrid assay that circumvents the difficulties in expressing P. falciparum proteins in Saccharomyces cerevisiae. From more than 32,000 yeast two-hybrid screens with P. falciparum protein fragments, we identified 2,846 unique interactions, most of which include at least one previously uncharacterized protein. Informatic analyses of network connectivity, coexpression of the genes encoding interacting fragments, and enrichment of specific protein domains or Gene Ontology annotations were used to identify groups of interacting proteins, including one implicated in chromatin modification, transcription, messenger RNA stability and ubiquitination, and another implicated in the invasion of host cells. These data constitute the first extensive description of the protein interaction network for this important human pathogen.

Huntington's disease (HD) is a fatal neurodegenerative condition caused by expansion of the polyglutamine tract in the huntingtin (Htt) protein. Neuronal toxicity in HD is thought to be, at least in part, a consequence of protein interactions involving mutant Htt. We therefore hypothesized that genetic modifiers of HD neurodegeneration should be enriched among Htt protein interactors. To test this idea, we identified a comprehensive set of Htt interactors using two complementary approaches: high-throughput yeast two-hybrid screening and affinity pull down followed by mass spectrometry. This effort led to the identification of 234 high-confidence Htt-associated proteins, 104 of which were found with the yeast method and 130 with the pull downs. We then tested an arbitrary set of 60 genes encoding interacting proteins for their ability to behave as genetic modifiers of neurodegeneration in a Drosophila model of HD. This high-content validation assay showed that 27 of 60 orthologs tested were high-confidence genetic modifiers, as modification was observed with more than one allele. The 45% hit rate for genetic modifiers seen among the interactors is an order of magnitude higher than the 1%–4% typically observed in unbiased genetic screens. Genetic modifiers were similarly represented among proteins discovered using yeast two-hybrid and pull-down/mass spectrometry methods, supporting the notion that these complementary technologies are equally useful in identifying biologically relevant proteins. Interacting proteins confirmed as modifiers of the neurodegeneration phenotype represent a diverse array of biological functions, including synaptic transmission, cytoskeletal organization, signal transduction, and transcription. Among the modifiers were 17 loss-of-function suppressors of neurodegeneration, which can be considered potential targets for therapeutic intervention. Finally, we show that seven interacting proteins from among 11 tested were able to co-immunoprecipitate with full-length Htt from mouse brain. These studies demonstrate that high-throughput screening for protein interactions combined with genetic validation in a model organism is a powerful approach for identifying novel candidate modifiers of polyglutamine toxicity.

Communicated by Alastair BrownClassical galactosemia is an autosomal recessive disorder caused by mutations in the galactose-1-phosphate uridyltransferase (GALT) gene. Our group developed a disease-specific database containing all of the reported sequence variants in GALT (

Hereditary hemorrhagic telangiectasia is a vascular dysplasia with variable onset and expression. Through identification of a mutation in a proband, mutation testing can be offered to family members. Mutation carriers can receive medical surveillance and treatment before potentially fatal complications arise. In this study, we assessed the significance of clinical evaluations as part of hereditary hemorrhagic telangiectasia diagnostic testing to determine the clinical sensitivity of molecular testing and to report novel mutations. Based on reported clinical symptoms, we classified 142 consecutive cases as affected, suspected, or unlikely affected. We performed temperature gradient capillary electrophoresis and full gene sequencing of both ACVRL1 and ENG genes. We then compared the mutation detection rates between these groups, categorizing sequence variants as mutations, variants of uncertain significance (VUS), or known polymorphisms. Our mutation and VUS detection rate in affected individuals was 74% and 16% in the suspected/unlikely affected group. Sixty-one percent of the mutations and all VUS were novel. The mutation detection rate for temperature gradient capillary electrophoresis was 97%. Our results suggest that a careful clinical evaluation increases the mutation detection rate. We have confirmed the occurrence of de novo mutations in three patients. Our results also show that temperature gradient capillary electrophoresis is an efficient mutation screening method. Hereditary hemorrhagic telangiectasia (HHT) is characterized phenotypically by telangiectases and arteriovenous malformations. These lesions result in hemorrhage, particularly in the nose, gastrointestinal tract, and brain, and complications related to shunting, primarily in the lungs and liver. Complications from this disorder include intracranial hemorrhage secondary to cerebral arteriovenous malformations and embolic stroke and brain abscess secondary to pulmonary arteriovenous malformations. The frequency of HHT is reported to be ϳ1 in 10,000, but it is thought to be underdiagnosed. 1Two genes, endoglin (ENG) and activin receptor-like kinase 1 (ACVRL1), have been reported to cause HHT in an autosomal dominant manner if mutated.2 Molecular diagnosis allows for diagnostic confirmation in symptomatic individuals and significantly improves care for individuals at risk for HHT after identification of a causative mutation. Because the initial clinical presentation of the disorder can be a catastrophic pulmonary or central nervous system event, 3-5 presymptomatic diagnosis for relatives of individuals with HHT offers an opportunity to prevent serious or lethal complications. Individuals shown to be unaffected can be spared unnecessary and costly medical screening. Developing simple and reliable diagnostic approaches has been difficult because of the lack of common mutations.2 Thus, sensitive mutation scanning approaches followed by targeted sequencing might be useful in the clinical setting.To detect mutations many scanning techniques have been ...

Fragile X syndrome , which is caused by expansion of a (CGG) n repeat in the FMR1 gene , occurs in approximately 1:3500 males and causes mental retardation/ behavioral problems. Smaller (CGG) n repeat expansions in FMR1, premutations , are associated with premature ovarian failure and fragile X-associated tremor/ataxia syndrome. An FMR1-sizing assay is technically challenging because of high GC content of the (CGG) n repeat , the size limitations of conventional PCR , and a lack of reference materials available for test development/validation and routine quality Fragile X syndrome (FXS) is the most common inherited cause of mental retardation, with an incidence in males of approximately 1 in 3500 (for a recent review, see http:// genetests.org). Clinical features in males include mental retardation, specific physical characteristics (enlarged testes, large ears, and long face), and behavioral abnormalities, sometimes including autism spectrum disorder. Affected females, with an incidence of approximately 1 in 8000, have mild mental retardation. Our knowledge of the spectrum of phenotypes associated with expansion of the FMR1 gene now also includes premature ovarian failure 1 and fragile X (FX)-associated tremor/ataxia syndrome.2-5 Thus, genetic testing for FX mutations is important at all life stages, prenatally to adulthood.

Acute rheumatic fever (ARF) is an autoimmune disease occurring in individuals following untreated group A streptococcal infection believed to be triggered by antibodies to bacterial components that cross-react with human tissues. We developed a multiplexed immunoassay for the simultaneous quantitation of antibodies to nine streptococcal-related antigens including streptolysin O (SLO), DNase B, collagen I and IV, fibronectin, myosin, group A carbohydrate, M6 protein and streptococcal C5a peptidase. Utilizing this method, we examined serum from 49 ARF, 58 pharyngitis patients and age- and sex-matched controls in samples collected at initial disease onset, and at 4 weeks, 6 months and 1 year after diagnosis. Antibody responses were significantly higher for SLO, DNase B, M6 protein, group A carbohydrate and the cross-reactive antigens collagen I and myosin in ARF compared with pharyngitis patients (P

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Background: Predisposition to venous thrombosis may be assessed through testing for defects and/or deficiencies of a number of hereditary factors. There is potential for confusion about which of these tests are appropriate in which settings. At least one set of recommendations has been published to guide such testing, but it is unclear how widely these have been disseminated.