Webster's New World Medical Dictionary

acquired mutation
A genetic change that occurs
in a single cell after the conception of an individual.
That change is then passed along to all cells
descended from that cell. Acquired mutations are
involved in the development of cancer.
acral-lentiginous melanoma
See 
melanoma,
acral-lentiginous.
acrocentric chromosome
A chromosome in
which the centromere is located quite near one end
of the chromosome. Humans normally have five
pairs of acrocentric chromosomes. Down syndrome
is caused by an extra acrocentric chromosome
(chromosome 21).
acrocephalosyndactyly
An inherited disorder
characterized by abnormalities of the skull, face,
hands, and feet. It begins with premature closure of
some sutures of the skull (craniosynostosis) and
results in a tall peaked head, shallow eye sockets,
and underdeveloped cheekbones. With acro-
cephalosyndactyly, fingers and toes are fused (syn-
dactyly), and the thumbs and big toes have broad
ends. Acrocephalosyndactyly is an autosomal domi-
nant trait that affects boys and girls. A parent can
transmit the gene for the disorder, or it can occur
due to a new mutation. Surgery is often useful to
correct the abnormalities of the skull, face, hands,
and feet. See also 
Apert syndrome; Crouzon 
syndrome.
acrochordon
See 
skin tag.
acrocyanosis
Blueness of the hands and feet,
usually due to inadequate circulation.
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acrocyanosis
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acrodermatitis enteropathica
A progressive,
hereditary disease of children, characterized by the
simultaneous occurrence of skin inflammation
(dermatitis) and diarrhea. The skin on the cheeks,
elbows, and knees is inflamed, as is tissue about the
mouth and anus. There is also balding of the scalp,
eyebrows, and lashes; delayed wound healing; and
recurrent bacterial and fungal infections due to
immune deficiency. The key laboratory finding is an
abnormally low blood zinc level, reflecting impaired
zinc uptake. Treatment with zinc by mouth is cura-
tive. Acrodermatitis enteropathica is an autosomal
recessive disorder. See also 
deficiency, zinc; zinc.