Webster's New World Medical Dictionary

chromosome complement
The whole set of
chromosomes for a species. In humans, the normal
chromosome complement consists of 46 chromo-
somes, including the 2 sex chromosomes. Also
known as the karyotype.
chromosome disorder
An abnormal condition
due to something unusual in an individual’s chromo-
somes. For example, Down syndrome is a chromo-
some disorder caused by the presence of an extra
copy of chromosome 21, and Turner syndrome is
most often due to the presence of only a single sex
chromosome: one X chromosome.
chromosome inversion
A condition in which a
chromosome segment is clipped out, turned upside
down, and reinserted back into the chromosome. A
chromatopsia
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chromosome inversion can be inherited from one
or both parents, or it may be a mutation that
appears in a child whose family has no history of
chromosome inversion. An inversion can be “bal-
anced,” meaning that it has all the genes that are
present in a normal chromosome; or it can be
“unbalanced,” meaning that genes have been
deleted (lost) or duplicated. A balanced inversion
causes no problems. An unbalanced inversion is
often associated with problems such as develop-
mental delay, mental retardation, and birth defects.
chromosome inversion, paracentric
A type of
chromosome rearrangement in which a chromoso-
mal segment that does not include the centromere
(and is therefore paracentric) is snipped out of a
chromosome, inverted, and inserted back into the
chromosome. The feature that makes it paracentric
is that both breaks are on the same side of the cen-
tromere, so that the centromere is not involved in
the rearrangement.