Webster's New World Medical Dictionary

disease, polygenic
A genetic disorder caused by
the combined action of more than one gene.
Examples of polygenic conditions include some
forms of coronary disease, hypertension, asthma,
and diabetes. Because such disorders depend on
the simultaneous presence of several genes, they are
not inherited as simply as single-gene diseases. See
also 
disease, single gene.
disease, single gene
A hereditary disorder
caused by a change (mutation) in a single gene.
There are thousands of single-gene diseases, includ-
ing achondroplasia, Huntington’s disease, cystic
fibrosis, sickle cell anemia, Duchenne muscular
dystrophy, and hemophilia. Single-gene diseases
typically describe classic simple Mendelian patterns
of inheritance (as autosomal dominant, autosomal
recessive, and X-linked traits), compared to poly-
genic diseases, which follow more complex patterns
of inheritance. See also 
disease, polygenic.
diseases, rickettsial
See 
rickettsial diseases.
DISH
Diffuse idiopathic skeletal hyperostosis.
disk, choked
See 
papilledema.
diskitis
Inflammation of the disks between the
vertebrae in the spinal column.
diskitis, tuberculous
See 
tuberculous diskitis.
disorder, attention deficit
See 
attention
deficit disorder.
disorder, lymphoproliferative
A malignant
disease of the lymphoid cells and of cells from the
reticuloendothelial system (lymph nodes and
drainage tissues that clear inert particles within the
body). A patient with lymphoproliferative disorder
has proliferation and accumulation of lymphoid
cells in the blood and marrow.
disorder, myeloproliferative
A malignant dis-
ease of certain bone marrow cells, including those
that give rise to the red blood cells, the granulocyte
(types of white blood cells), and the platelets
(which are crucial to blood clotting). The four
major myeloproliferative disorders are poly-
cythemia vera, myelofibrosis, thrombocythemia,
and chronic myeloid leukemia (CML).