These studies are now being done by GWAS in 2 patient groups, examining both baseline HbF and the HbF response to hydroxyurea. Genetic modulation of sickle cell disease: Homozygosity for a single Î²-globin gene mutation (HBB; glu6val) causes sickle cell anemia.hese studies are now being done by GWAS in 2 patient groups, examining both baseline HbF and the HbF response to hydroxyurea. Genetic modulation of sickle cell disease: Homozygosity for a single Î²-globin gene mutation (HBB; glu6val) causes sickle cell anemia.
Spiral Galaxies. Spiral galaxy M100. Spiral galaxies have three main components: a bulge, disk, and halo (see right). The bulge is a spherical structure found in the center of the galaxy. This feature mostly contains older stars. The disk is made up of dust, gas, and younger stars. The disk forms arm structures.
Oasis in Space. Galaxies are defined as large groupings of stars, dust, and gas held together by gravity. They vary greatly in size and shape. Most of the objects we know of in space are contained within galaxies. They contain stars, planets, moons, comets, asteroids, nebulae, dust, neutron stars, and black holes. Many probably even contain large amounts of unseen dark matter. Since most of the space between galaxies is thought to be empty, a galaxy is essentially an oasis in space. Our own solar system is located within a galaxy. Our Sun is only one of over 100 billion stars in a galaxy called the Milky Way.