Webster's New World Medical Dictionary

major depression
See 
depression, major.
major histocompatability complex
A cluster
of genes on chromosome 6 that encode a class of
cell surface molecules that are important for anti-
gen production and are critical in organ transplan-
tation. Abbreviated MHC. The MHC includes the
human leukocyte antigen (HLA) genes.
malabsorption
Poor intestinal absorption of
nutrients. Malabsorption can occur from diseases
that injure the bowels, such as Crohn’s disease,
Whipple’s disease, celiac disease, and many others.
malacia
Softening. For example, osteomalacia is
softening of bone, usually due to deficiency of cal-
cium and vitamin D.
malady
A disease or an illness, from the French
maladie,
meaning “illness.”
malaise
A vague feeling of discomfort, one that
cannot be pinned down but is often sensed as “just
not right.”
malar
Referring to the cheek. For example, a
malar rash is a rash that appears over the cheeks.
malar bone
The zygoma. See also 
zygoma.
malar rash
Rash over the cheeks. See also 
but-
terfly rash.
malaria
An infectious disease that affects many
millions of people and is caused by protozoan par-
asites from the Plasmodium family. These parasites
can be transmitted by the sting of the Anopheles
mosquito or by a contaminated needle or transfu-
sion. The symptoms of malaria include cycles of
chills, fever, sweats, muscle aches, and headache
that recur every few days. Other symptoms include
vomiting, diarrhea, coughing, and yellowing of the
skin and eyes (jaundice). Treatment includes use of
oral or intravenous medication, particularly chloro-
quine, mefloquine (brand name: Larium), or ato-
vaquone/proguanil (brand name: Malarone).
Anti-malarial drugs can be taken by those traveling
to endemic areas for prevention of malaria. Persons
carrying the sickle cell gene have some protection
against malaria. Among the many names for malaria
are ague, jungle fever, marsh or swamp fever, and
paludism. See also 
malaria, falciparum.