Webster's New World Medical Dictionary

Hansen’s disease
See 
leprosy.
hantavirus
A group of viruses that cause hemor-
rhagic fever and pneumonia. The hantaviruses
include the hantaan virus that causes Korean (and
Manchurian) hemorrhagic fever. Hantaviruses are
transmitted to humans by direct or indirect contact
with the saliva and excreta of rodents, such as deer
mice, field mice, and ground voles.
hantavirus pulmonary syndrome
A severe
lung condition caused by hantavirus infection.
Abbreviated HPS. In 1993, HPS struck the Four
Corners area (where the states of Arizona, New
Mexico, Nevada, and Utah meet) with devastating,
frequently fatal consequences. As the name indi-
cates, HPS is due to a hantavirus. The HPS outbreak
in Four Corners followed 2 years of more rain,
more foliage, and more deer mice than usual.
haploid
A set of chromosomes that contains only
one member of each chromosome pair. The sperm
and egg are haploid and, in humans, each has 23
chromosomes.
haplotype 1
A set of closely linked genetic mark-
ers present on one chromosome that tend to be
inherited as a unit, such as those genes of the major
histocompatibility complex (MHC).
2
A pheno-
type (set of characteristics) determined by closely
linked genes inherited as a unit from one parent.
hard measles
See 
measles.
hard palate
The first section of the bony part of
the roof of the mouth, located in front of the soft
palate.
Hardy-Weinberg law
A basic concept in popula-
tion genetics that relates the gene frequency to the
genotype frequency. The Hardy-Weinberg law can be
used, for example, to determine allele frequency and
heterozygote frequency when the incidence of a
genetic disorder is known.