Canadian Medical Guide > Diseases > Pathological Conditions, Signs and Symptoms > Pathologic Processes > Chromosome Aberrations Terms and Definitions

Chromosome Aberrations

Medical Definition:	Abnormal number or structure of chromosomes. Many chromosome aberrations, but not all, are the cause of CHROMOSOME DISORDERS.
Guide Notes:	coord IM with specific numbered chromosome or sex chromosome (IM) but not with CHROMOSOMES, HUMAN
Also Called:	Abnormal Karyotype,Autosome Abnormalities
Previously Indexed:	Chromosome Abnormalities (1966-1967)

Chromosome Aberrations Categories.

	Aneuploidy - The chromosomal constitution of cells which deviate from the normal by the addition or subtraction of CHROMOSOMES, chromosome pairs, or chromosome fragments. In a normally diploid cell (DIPLOIDY) the loss of a chromosome pair is termed nullisomy (symbol: 2N-2), the loss of a single chromosome is MONOSOMY (symbol: 2N-1), the addition of a chromosome pair is tetrasomy (symbol: 2N+2), the addition of a single chromosome is TRISOMY (symbol: 2N+1).
	Chromosomal Instability - An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.
	Chromosome Deletion - Actual loss of a portion of the chromosome.
	Inversion (Genetics) - An aberration in which a chromosomal segment is deleted and reinserted in the same place but turned 180 degrees from its original orientation, so that the gene sequence for the segment is reversed with respect to that of the rest of the chromosome.
	Nondisjunction, Genetic - The failure of homologous CHROMOSOMES or CHROMATIDS to segregate during MITOSIS or MEIOSIS with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none.
	Sex Chromosome Aberrations - Abnormal number or structure of the SEX CHROMOSOMES. Many sex chromosome aberrations, but not all, are the cause of SEX CHROMOSOME DISORDERS.
	Translocation (Genetics) - A type of aberration characterized by fragmentation of a chromosome and transfer of the broken-off portion to another chromosome, often of a different pair.

Chromosome Aberrations Medical Definitions and Terms

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