Webster's New World Medical Dictionary

pharyngitis
Inflammation of the pharynx.
Pharyngitis is a common cause of sore throat.
pharynx
The hollow tube that is about 5 inches
long and starts behind the nose and ends at the top
of the trachea (windpipe) and esophagus. The
pharynx serves as a vestibule or entryway for the tra-
chea and esophagus.
phase, resting
See 
interphase.
PhD
Doctor of Philosophy. PhDs are involved in
clinical care, biomedical research, health adminis-
tration, teaching, and other areas of medicine.
Phe
Phenylalanine.
phenocopy 1
An environmental condition that
imitates a condition that is produced by a gene.
2
A person who has an environmental condition that
mimics a condition that is produced by a gene.
phenomenon, Babinski
See 
Babinski reflex.
phenomenon, phantom limb
See 
phantom
limb syndrome.
phenomenon, Raynaud’s
See 
Raynaud’s
phenomenon.
phenotype
An appearance or characteristic of an
individual, which results from the interaction of the
person’s genetic makeup and his or her environ-
ment. By contrast, the genotype is merely the genetic
constitution (genome) of an individual.
phenylalanine
An essential amino acid that is
required in the human diet. Abbreviated phe. Most
of the phe that is ingested is transformed (hydroxy-
lated) to form tyrosine, which is used in protein
synthesis. Too little phe does not permit normal
physical and intellectual growth. Too much phe (as
in PKU) is highly toxic to the brain. See also 
pheny-
lalanine hydroxylase deficiency; PKU; PKU,
maternal.
phenylalanine hydroxylase deficiency
The
inherited inability to normally process the amino acid
phenylalanine, due to partial or complete deficiency
of the enzyme phenylalanine hydroxylase. This defi-
ciency is caused by mutation in the PAH gene
on chromosome 12. Phenylalanine hydroxylase
deficiency causes a spectrum of disorders, including
classic phenylketonuria (PKU), variant PKU, and non-
PKU elevation of phenylalanine in the blood (non-
PKU HPA). See also 
PKU; PKU, maternal.