Webster's New World Medical Dictionary

Canavan disease
A progressive, inherited disor-
der of the central nervous system that is caused by a
deficiency of the enzyme aspartoacylase. Signs
appearing in children between 3 and 6 months of
age include developmental delay, significant motor
slowness, enlargement of the head (macrocephaly),
loss of muscle tone (hypotonia), poor head control,
and severe feeding problems. As the disease pro-
gresses, seizures, shrinkage of the nerve to the eye
(optic atrophy), and often blindness develop, as do
heartburn (gastrointestinal reflux) and deteriora-
tion of the ability to swallow. Canavan disease is
inherited as an autosomal recessive condition, with
both parents silently carrying a single Canavan gene
and each of their children running a 25 percent risk
of receiving both genes and having the disease.
Canavan disease is more prevalent among individu-
als of Eastern European Jewish (Ashkenazi) back-
ground than in others. There is currently no
effective treatment and affected children die in the
first decade of life. Also known as spongy degener-
ation of the central nervous system and Canavan-Van
Bogaert-Bertrand disease.
cancer
An abnormal growth of cells that tend to
proliferate in an uncontrolled way and, in some
cases, to metastasize (spread) to other areas of the
body. Cancer is not one disease; rather, it is a host
of more than 100 different and distinctive diseases.
A tumor can involve any tissue of the body. Most
types of cancer are named for the type of cell or
organ in which they start. If a cancer metastasizes,
the new tumor bears the same name as the original
primary tumor. Skin cancer is the most common
type of cancer in both men and women. The second
most common types of cancer are prostate cancer
in men and breast cancer in women. Lung cancer is
the leading cause of death from cancer for both
men and women in the US. Cancer is not conta-
gious. Also known as malignancy, malignant tumor,
and malignant neoplasm. See also 
cancer, causes.