In the literature there are met over 5000 types of monogenic disorders
due to disturbances in the functions of only one gene are known by now.
More widely spread among them are thalassemia, phenylketonuria,
mucoviscidosis, hemophilia, etc.
Down\u2019s syndrome is the most widely spread chromosome ailment in
the human population. It is caused by the trisomy of chromosome 21
(Fig. 2\u201323). The formula of Down\u2019s syndrome is 47, XY, +21 for boys
and 47, XX+21 for girls.<\/p>\n\n\n\n
image<\/p>\n\n\n\n
Figure 2\u201323. Trisomy of chromosome 21. Arrous indicate the three \ncopies of the chromosome (Courtesy of A. Andreev, Laboratory of \nCytogenetics at the State University Pediatric Hospital, Sofia).<\/pre>\n\n\n\nAs was mentioned in Section 2. 5 giant and lampbrush type chromosomes
have been discovered in the cell nuclei from tissues specific of certain organisms
(Balbiani, 1881; Flemming, 1882). The interest towards them has considerably
grown in half a century when they were rediscovered by a number of authors
(Painter, 1933\u201435; Heitz, Bauer, 1933; King, Beams, 1934; Bridges, 1935; Bauer,
1935, 1936, etc.). Such chromosomes have been observed in the salivary glands
of Drosophila, Chironomus <\/em>and some other two-winged insects of the Diptera<\/em>
order.
The giant chromosomes (Fig. 2\u201324) are formed as a result from the
manifold replication cycles in them, which are not accompanied by release
and distribution of the chromatids in the daughter cells as it is normally
taking place in mitosis and cytokinesis. That is why there is a multiple<\/p>\n","protected":false},"excerpt":{"rendered":"In the literature there are met over 5000 types of monogenic disordersdue to disturbances in the functions of only one gene are known by now.More widely spread among them are thalassemia, phenylketonuria, mucoviscidosis, hemophilia, etc.Down\u2019s syndrome is the most widely spread chromosome ailment inthe human population. It is caused by the trisomy of chromosome 21(Fig. […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[6],"tags":[],"class_list":["post-545","post","type-post","status-publish","format-standard","hentry","category-book"],"_links":{"self":[{"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=\/wp\/v2\/posts\/545","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=545"}],"version-history":[{"count":1,"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=\/wp\/v2\/posts\/545\/revisions"}],"predecessor-version":[{"id":550,"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=\/wp\/v2\/posts\/545\/revisions\/550"}],"wp:attachment":[{"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=545"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=545"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cellandcelldivision.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=545"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}