{"id":494,"date":"2018-04-19T19:33:06","date_gmt":"2018-04-19T19:33:06","guid":{"rendered":"http:\/\/haema-journal.gr\/?p=494"},"modified":"2018-04-24T20:51:34","modified_gmt":"2018-04-24T20:51:34","slug":"%ce%b1-thalassemia-h-hemoglobinopathy-and-unstable-%ce%b1-globin-chains","status":"publish","type":"post","link":"https:\/\/haema-journal.gr\/?p=494","title":{"rendered":"\u03b1- thalassemia, H hemoglobinopathy and unstable \u03b1 globin chains"},"content":{"rendered":"<p style=\"text-align: right;\"><em>Haema 2011; 2(2): 254-261<br \/>\n<\/em><\/p>\n<p>by Emmanuel Kanavakis<sup>1<\/sup>, Joanne Traeger-Synodinos<sup>1<\/sup>, Varvara Douna<sup>2<\/sup><\/p>\n<p><sup>1<\/sup>Department of Medical Genetics, Athens University, St. Sophia\u2019s Children\u2019s Hospital, Athens, <sup>2<\/sup>Hematology Laboratory \u201cP. &amp; A. Kyriakou\u201d, Athens<\/p>\n<p style=\"text-align: right;\"><a href=\"http:\/\/haema-journal.gr\/PDF\/2011\/HAEMA_2011-254.pdf\" target=\"_blank\" rel=\"noopener\">Full PDF (in Greek)<\/a> | <a href=\"http:\/\/haema-journal.gr\/PDF\/2011\/HAEMA_2011-254.pdf\" target=\"_blank\" rel=\"noopener\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-390 size-full\" src=\"http:\/\/haema-journal.gr\/wp-content\/uploads\/2018\/02\/PDF-icon.jpg\" alt=\"\" width=\"36\" height=\"36\" \/><\/a> <\/p>\n<p><!--more--><\/p>\n<h5><strong>Abstract<\/strong><\/h5>\n<p style=\"text-align: justify;\">The synthesis of \u03b1-globin chains is directed by the duplicated \u03b1-globin genes (HBA1 \u03ba\u03b1\u03b9 \u0397\u0392\u03912 \u03ae a1 \u03ba\u03b1\u03b9 a2) located at the tip of the short arm of chromosome 16 (16p13.3). Mutations that reduce the synthesis of \u03b1-globin chains cause \u03b1-thalassemia (\u03b1-thal), and over than 120 have been described worldwide (\u0397b Var http:\/\/globin.cse.psu.edu\/hbvar\/). The majority of the most common \u03b1-thal determinants are deletions that remove some, or all of, the \u03b1-globin gene cluster. Less common are single nucleotide (nt) substitutions or micro deletions within either the \u03b11- or \u03b12-globin genes, also known as nondeletional mutations. An apparent reduction in \u03b1-globin chain synthesis can also be caused by substitutions that give rise to hyperunstable \u03b1-globin chains. In most cases, these variants are so unstable that they cannot be detected at the protein level, and can only be deduced from the DNA sequence. In Greece, \u03b1-thal has an estimated carrier frequency of 8.0%, with over 20 different mutations observed to date. According to the number of a genes with impaired function, four major hematological and clinical phenotypes can be characterized. Coinheritance of a thalassemia mutations may lead to the expression of clinically relevant conditions, most noteably Hb Bart\u2019s hydrops fetalis and Hb H disease. HbH disease is the severest form of a thalassemia compatible with postnatal life, and it occurs when a thalassemia mutations interact to reduce a globin synthesis to levels approximately equivalent to the output of a single a globin gene. The clinical severity of Hb H disease may vary considerably, but strongly correlates with the underlying a thalassemia genotype. Patients with genotypes involving hyperunstable \u03b1-globin chain variants (either in the homozygous or compound heterozygous state with typical haploinsufficient a thalassemia mutations) may have classical Hb H disease, but also may have a condition with clinical and hematological findings similar to \u03b2-thal intermedia and very rarely HbH-hydrops.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Haema 2011; 2(2): 254-261 by Emmanuel Kanavakis1, Joanne Traeger-Synodinos1, Varvara Douna2 1Department of Medical Genetics, Athens University, St. Sophia\u2019s Children\u2019s Hospital, Athens, 2Hematology Laboratory \u201cP. &amp; A. Kyriakou\u201d, Athens Full PDF (in Greek) |<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[38],"tags":[],"class_list":["post-494","post","type-post","status-publish","format-standard","hentry","category-haema-2011-3"],"_links":{"self":[{"href":"https:\/\/haema-journal.gr\/index.php?rest_route=\/wp\/v2\/posts\/494","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/haema-journal.gr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/haema-journal.gr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/haema-journal.gr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/haema-journal.gr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=494"}],"version-history":[{"count":3,"href":"https:\/\/haema-journal.gr\/index.php?rest_route=\/wp\/v2\/posts\/494\/revisions"}],"predecessor-version":[{"id":840,"href":"https:\/\/haema-journal.gr\/index.php?rest_route=\/wp\/v2\/posts\/494\/revisions\/840"}],"wp:attachment":[{"href":"https:\/\/haema-journal.gr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=494"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/haema-journal.gr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=494"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/haema-journal.gr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=494"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}