{"id":4422568,"date":"2025-01-12T06:04:47","date_gmt":"2025-01-12T12:04:47","guid":{"rendered":"https:\/\/myendoconsult.com\/learn\/topics\/tangier-and-abetalipoproteinemia\/"},"modified":"2025-01-13T07:07:33","modified_gmt":"2025-01-13T13:07:33","slug":"tangier-and-abetalipoproteinemia","status":"publish","type":"oen_topic","link":"https:\/\/myendoconsult.com\/learn\/topics\/tangier-and-abetalipoproteinemia\/","title":{"rendered":"Tangier and abetalipoproteinemia"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">ABETALIPOPROTEINEMIA<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Genetics and Mechanism<\/strong>\n<ul class=\"wp-block-list\">\n<li>Autosomal recessive disorder.<\/li>\n\n\n\n<li>Caused by mutations in the gene encoding the large subunit of <strong>microsomal triglyceride transfer protein<\/strong>.<\/li>\n\n\n\n<li>Leads to <strong>abnormal production and secretion of apolipoprotein B (apo B)<\/strong> and <strong>apo B\u2013containing lipoproteins<\/strong>.<\/li>\n\n\n\n<li>Insufficient lipidation of nascent particles prevents normal synthesis and secretion of <strong>chylomicrons<\/strong> (intestine) and <strong>VLDL<\/strong> (liver).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Clinical Presentation<\/strong>\n<ul class=\"wp-block-list\">\n<li>Usually presents in <strong>infancy<\/strong> with:\n<ul class=\"wp-block-list\">\n<li>Fat malabsorption<\/li>\n\n\n\n<li><strong>Hypocholesterolemia<\/strong><\/li>\n\n\n\n<li><strong>Acanthocytosis<\/strong> (crenated RBCs)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Later in life:\n<ul class=\"wp-block-list\">\n<li>Deficiencies in <strong>fat-soluble vitamins<\/strong> (A, D, E, K)<\/li>\n\n\n\n<li><strong>Neurologic complications<\/strong>: atypical retinitis pigmentosa, posterior column neuropathy, myopathy<\/li>\n\n\n\n<li>Retinal changes, peripheral neuropathy, ataxia, lordosis (from muscular weakness), sensory motor neuropathy, mental retardation<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Children appear malnourished, show <strong>growth retardation<\/strong>.<\/li>\n\n\n\n<li>Some develop <strong>hepatic steatosis<\/strong> and cirrhosis (possibly related to medium-chain triglyceride therapy).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Laboratory Findings<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Absence<\/strong> of plasma apo B\u2013containing lipoproteins<\/li>\n\n\n\n<li>Extremely <strong>low plasma cholesterol<\/strong> (&lt;50 mg\/dL)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Pathophysiology<\/strong>\n<ul class=\"wp-block-list\">\n<li>Microsomal triglyceride transfer protein is essential for loading triglycerides and phospholipids into the lumen of the endoplasmic reticulum.<\/li>\n\n\n\n<li>Without it, chylomicrons &amp; VLDL cannot form or be secreted \u2192 fat malabsorption &amp; lipid-poor plasma.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Treatment<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Lipid-poor diet<\/strong> to address digestive intolerance (low daily fat intake, e.g., 5 g\/day in children).<\/li>\n\n\n\n<li>Provide <strong>dietary essential fatty acids<\/strong> (e.g., vegetable oils).<\/li>\n\n\n\n<li><strong>High-dose fat-soluble vitamins<\/strong> (A, D, E, K) supplementation.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">TANGIER DISEASE<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Genetics and Mechanism<\/strong>\n<ul class=\"wp-block-list\">\n<li>Autosomal dominant disorder.<\/li>\n\n\n\n<li><strong>Mutations in ABCA1<\/strong> (adenosine triphosphate\u2013binding cassette transporter-1 gene).<\/li>\n\n\n\n<li>ABCA1 crucial for <strong>cholesterol efflux<\/strong> from cells onto nascent HDL \u2192 decreased cholesterol efflux \u2192 low plasma HDL levels.<\/li>\n\n\n\n<li>Homozygotes: almost <strong>absent plasma HDL<\/strong>.<\/li>\n\n\n\n<li>Heterozygotes: ~50% normal HDL levels.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Clinical Presentation<\/strong>\n<ul class=\"wp-block-list\">\n<li>Named for the kindred on <strong>Tangier Island<\/strong> (Chesapeake Bay).<\/li>\n\n\n\n<li><strong>Orange-colored tonsils<\/strong> (cholesterol deposits).<\/li>\n\n\n\n<li><strong>Corneal opacities<\/strong>.<\/li>\n\n\n\n<li><strong>Hepatosplenomegaly<\/strong> (due to foam cell accumulation).<\/li>\n\n\n\n<li><strong>Peripheral neuropathy<\/strong>.<\/li>\n\n\n\n<li>Increased risk for <strong>premature coronary disease<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Laboratory Findings<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Very low to absent HDL<\/strong> cholesterol.<\/li>\n\n\n\n<li><strong>Low total cholesterol<\/strong>.<\/li>\n\n\n\n<li>Overaccumulation of macrophage cholesteryl esters (foam cells).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Treatment<\/strong>\n<ul class=\"wp-block-list\">\n<li>No disease-specific treatment currently available.<\/li>\n\n\n\n<li>Management focuses on general measures for <strong>cardiovascular risk reduction<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>ABETALIPOPROTEINEMIA TANGIER DISEASE<\/p>\n","protected":false},"featured_media":0,"template":"","oen_topic_chapter":[688],"class_list":["post-4422568","oen_topic","type-oen_topic","status-publish","hentry","oen_topic_chapter-lipid-metabolism","post-wrapper","thrv_wrapper"],"_links":{"self":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422568","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic"}],"about":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/types\/oen_topic"}],"version-history":[{"count":4,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422568\/revisions"}],"predecessor-version":[{"id":4422876,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422568\/revisions\/4422876"}],"wp:attachment":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/media?parent=4422568"}],"wp:term":[{"taxonomy":"oen_topic_chapter","embeddable":true,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic_chapter?post=4422568"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}