Webster's New World Medical Dictionary

nail fungus
See 
onychomycosis.
nail furrows
Transverse lines or grooves across
the fingernails; transverse depressions in the nail
plate caused by temporary cessation of cell division
in the proximal nail matrix. The condition may be
caused by local disease of the nail fold, physical
trauma to it, or a systemic insult, such as an illness
or a drug as, for example, chemotherapy. Also
known as Beau’s lines.
nail-patella syndrome
A hereditary condition
that is characterized by abnormally formed or
absent nails and underdeveloped or absent
kneecaps. Abbreviated NPS. Other features of NPS
include iliac horns; elbow abnormalities that inter-
fere with full range of motion (pronation and
supination); glaucoma; and kidney disease that
resembles glomerulonephritis, which can be pro-
gressive and lead to kidney failure. NPS is inherited
as an autosomal dominant trait. NPS is caused by
mutations in a gene LMX1B (the LIM homeobox
transcription factor 1, beta gene) on chromosome
9. Also known as hereditary osteo-onychodysplasia,
Fong disease, and Turner-Kieser syndrome.
nails, jogger’s
See 
jogger’s nails.
nails, ringworm of the
See 
onychomycosis.
nails, white spots on the
See 
jogger’s nails.
nanism
See 
dwarfism.
narcolepsy
A neurological disorder that is
marked by the recurrent, sudden, uncontrollable
compulsion to sleep. Narcolepsy is often associated
with cataplexy (a sudden loss of muscle tone and
paralysis of voluntary muscles associated with a
strong emotion), sleep paralysis (immobility of the
body that occurs in the transition from sleep to
wakefulness), hypnagogic hallucinations (presleep
dreams), and automatic behaviors (such as doing
something “automatically” and not remembering
afterward how one did it). The causes of narcolepsy
are unknown. Narcolepsy is not a fatal disorder in
itself, but it can lead to fatalities. For example,
affected persons may fall asleep while driving. Also
known as excessive daytime sleepiness, hypnolepsy,
sleeping disease, paroxysmal sleep, and Gelineau
syndrome.