Naming of Chromosome Pairs

[b3n3llis]

With 23 pairs of chromosomes in a human, how is each pair named and differentiated, if at all?

 

There's Chromosome 1, 2, 3, 4, etc but how is it each pair differentiated, eg. 1a, 1b or 1p, 1m (parental/maternal) or 1xx, 1xy? One pair of shoes are differentiated by 'left' and 'right', whatabout chromosomes?

 

If they're not, why not?

 

Many thanks.

[Kookas]

http://www.chromodis...hromosomes.aspx

 

It's about halfway down the page.

 

How are Chromosomes and Chromosome Abnormalities Labeled?

In 1960 the first meeting to propose a standard system of naming the chromosomes took place. Since that time this method of describing chromosomes and chromosome abnormalities has been revised and added to several times. It has produced an International Standard of Cytogenetic Nomenclature. This allows one lab to 'write out' the chromosome findings. Any other lab will know what they have found without looking at the karyotype.

 

Here are some examples:

 

46,XX - Normal Female Karyotype

46,XY - Normal Male Karyotype

 

These descriptions say there are 46 chromosomes and that it is a male or female.

 

46,XX,del(14)(q23)

 

Female with 46 chromosomes with a deletion of chromosome 14 on the long arm (q) at band 23.

 

46,XY,dup(14)(q22q25)

 

Male with 46 chromosomes with a duplication of chromosome 14 on the long arm (q) involving bands 22 to 25.

 

46,XX,r(7)(p22q36)

 

Female with 46 chromosomes with a 7 chromosome ring. The end of the short arm (p22) has fused to the end of the long arm (q36) forming a circle or 'ring'

 

47,XY,+21

 

Male with 47 instead of 46 chromosomes and the extra chromosome is a 21. (Down Syndrome)

 

There are literally millions of types of abnormalities. If your child has a chromosome abnormality the above nomenclature describes exactly what it is. Ask your genetic counselor, physician, or health care professional to describe the chromosome abnormality found. Below are a few of the codes used in the standard nomenclature.

 

add = Addition material of unknown origin del = Deletion de novo = A chromosome abnormality which has not been inherited der = Derivative Chromosome dic Dicentric dup = Duplication fra = Fragile Site idic = Isodicentric chromosome ins = Insertion inv = Inversion i or iso = Isochromosome mar = Marker chromosome mat = Maternal origin Minus sign (-) = Loss mos = Mosaic p = Short arm of chromosome pat = Paternal origin Plus sign(+) = Gain q = Long arm of chromosome r = Ring chromosome rcp = Reciprocal rea = Rearrangement rec = Recombinant chromosome rob = Robertsonian translocation t = translocation tel = Telomere (end of chromosome arm) ter = Terminal end of chromosome upd = Uniparental disomy ? = Uncertain It is important to note that most chromosome abnormalities occur as a accident in the egg or sperm. Therefore every cell in the body would have the abnormality. Some abnormalities can happen after conception and individuals can have a mosaicism (some cells with the abnormality and some without). Chromosome abnormalities can be inherited from a parent, like a translocation, or be 'de novo' (new in that individual).

 

I hope that's what you were looking for

Edited August 2, 2011 by Kookas