Webster's New World Medical Dictionary

typhus, tick
See 
Rocky Mountain spotted fever.
typhus, tropical
See 
typhus, scrub.
typhus, urban, of Malaysia
See 
typhus,
murine.
typist’s cramp
A dystonia that affects the muscles
of the hand and sometimes the forearm and occurs
only during handwriting. See also 
dystonia, focal.
tyrosinemia
A genetic disorder that involves the
metabolism of the amino acid tyrosine and is char-
acterized by abnormally high levels of tyrosine in
blood (hypertyrosinemia) and urine (tyrosinuria).
There are several forms of tyrosinemia. Tyrosinemia
type I is due to deficiency of fumarylacetoacetase,
the last enzyme in the tyrosine catabolism pathway
(the biochemical reactions that break down tyro-
sine). An acute form surfaces soon after birth, with
the odor of cabbage and death from liver failure in
infancy. A chronic form is characterized by chronic
liver disease, rickets due to hypophosphatemia (low
phosphate), and death in childhood. There is an
association with liver cancer (hepatocellular carci-
noma). Tyrosinemia type II is due to deficiency of
the enzyme tyrosine transaminase and is character-
ized by the crystallization of tyrosine in painful thick
areas on the palms and soles and in the cornea and
often by mental retardation. Type III tyrosinemia is
a rare disorder caused by a deficiency of the enzyme
4-hydroxyphenylpyruvate dioxygenase and is char-
acterized by mild mental retardation and seizures.
Tyrosinemia types I, II, and III are inherited in an
autosomal recessive manner.
437
tyrosinemia
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