Missing Genetic Link found in a Challenging Immune Disease In the largest genome-wide analysis to date of #CVID Common Variable Immunodeficiency Disorder, scientists have identified a gene that may be a ‘#missing #link’ between #overactive and #underactive immune activity. They analyzed CVID in which weak antibody responses lead to recurrent, oft severe #bacterial respiratory tract infections. “… it raises new opportunities for understanding underlying causes of different immune disorders, and eventually developing more effective diagnostic tests and therapies,” >>#Defective #Bcells in the immune system cause a low level of antibodies, leaving patients vulnerable to recurrent infections >> may cause permanent lung damage. At least 25% of patients with CVID have various autoimmune disorders. eg RA, stomach and bowel disorders, and autoimmune thrombocytopenia, lymphoma. Thus many CVID patients develop symptoms from admixture of both #insufficient and #overactive immune components of immune dysfunction. #METHOD: scientists searched for genetic differences b/n 778 patients with CVID and 11,000 control patients. They used #Immunochip, a genotyping tool customized to detect hundreds of thousands of single-nucleotide polymorphisms (#SNPs) already a/w 12 immune-related diseases. >> Hakonarson & CHOP colleagues had discovered in 2011 CVID was linked to the #HLA-related gene region on chrom #6p21. In this new study, they also found a robust, novel candidate for #risk gene in CVID: #CLEC16A gene region on chromosome 16p13.13. “This is the first risk susceptibility gene for CVID identified by a genome-wide association study that does not code for the HLA complex,” + showed that mice with #reduced activity in the corresponding animal gene had lower levels of B cells which are depleted in human disease + prev. genetic studies found changes in CLEC16A raised the risk of type 1 diabetes, IBD and other autoimmune disorders. “The biological mechanisms that cause disease symptoms in CVID are still unclear,” added Hakonarson, “but this study may suggest that altered function in CLEC16A and its associated proteins may represent a ‘missing link’ between immunodeficiency and autoimmunity in CVID. This may offer new opportunities for eventually designing more effective treatments.” http://bit.ly/1Df0bay

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