mucopolysaccharidosisA group of rare
inherited metabolic disorders (see met-
abolism, inborn errors of) of which
Hurler’s syndromeis the best known. All
mucopolysaccharidoses are genetic dis-
ordersin which there is an abnormality
of a specific enzyme. This leads to the
accumulation within body cells of sub-
stances called mucopolysaccharides.
Features may include abnormalities of
the skeleton and/or the central nervous
system, with learning difficultiesand,
in some cases, a characteristic facial
appearance. There may also be clouding
of the cornea, liver enlargement, and
joint stiffness. No specific treatment is
available. However, a bone marrow
transplantmay successfully be used to
treat Hurler’s syndrome.
Mild forms of mucopolysaccharidoses
allow a child to have a relatively normal
life. More severe types usually cause
death during childhood or adolescence.
mucosaA term for mucous membrane.
mucous membraneThe soft, pink,
skin-like layer that lines many of the
cavities and tubes in the body, including
the respiratory tractand the digestive
tract. Mucous membranes contain mil-
lions of cells called goblet cells, which
secrete a fluid containing mucus.
mucoviscidosisSee cystic fibrosis.
mucusThe thick, slimy fluid secreted by
mucous membranes. Mucus moistens,
lubricates, and protects parts of the body
lined by mucous membranes, such as
the digestive and respiratory tracts.
mucus method of contraception
See contraception, natural methods of.
multiple myelomaAlso called myelo-
matosis, multiple myeloma is a rare,
cancerous condition in which plasma
cells in the bone marrowproliferate
uncontrollably and function incorrectly.
It occurs in middle- to old age.
Plasma cells are a type of B-lymphocyte
that produce immunoglobulins, which
help protect against infection. In multi-
ple myeloma, the proliferating plasma
cells produce excessive amounts of one
type of immunoglobulin, while produc-
tion of other types is impaired. This
makes infection more likely.
Proliferation of the abnormal cells
causes pain and destroys bone tissue.
Affected vertebraemay collapse and
compress nerves, causing numbness or
paralysis. Blood calcium levels increase
as bone is destroyed, as may the level
of one or more immunoglobulins.
These changes in the blood may dam-
age the kidneys, leading to kidney
failure. There may also be anaemiaand
a tendency for abnormal bleeding.
The disease is diagnosed by a bone
marrow biopsy, by blood testsor urinal-
ysis, and by X-rays. Treatment includes
the use of anticancer drugs, radiothera-
py, and supportive measures, including
blood transfusions, antibiotic drugs, and
analgesic drugs.
multiple personalityA rare disorder
in which a person has 2 or more distinct
personalities, each of which dominates
at different times. The personalities are
usually very different from each other.
multiple pregnancySee pregnancy,
multiple.
multiple sclerosisA progressive dis-
ease of the central nervous systemin
which patches of myelinin the brain
and spinal cord are destroyed. Multiple
sclerosis (or MS) is an autoimmune dis-
order, in which the immune system
attacks the myelin sheath that covers
some nerves in the brain and spinal
cord. Affected nerves cannot conduct
nerve impulses, so functions such as
movement and sensation may be lost.
Any area of the body can be affected.
Symptoms range from numbness and
tingling to paralysisand incontinence.
Attacks of symptoms are followed by a
variable period of remission, in which
dramatic improvements may be made.
Women are more likely to develop MS
than men, and there may be a genetic
factor, as the disease sometimes runs in
families. There may also be an environ-
mental factor, as MS is more common
in temperate zones than in the tropics.
Symptoms usually develop early in
adulthood. Spinal cord damage may
cause tingling, numbness, weakness in
the extremities, spasticity, paralysis, and
incontinence. Damage to white matter
(myelinated nerves) in the brain may
cause fatigue, vertigo, clumsiness, muscle
weakness, slurred speech, blurred vision,
numbness, weakness, or facial pain.MUCOPOLYSACCHARIDOSIS MULTIPLE SCLEROSIS
M