Analysis of Ring Shaped Marker Chromosomes

Ring shaped marker chromosomes are ring chromosomes of unknown origin. They are denoted with the symbol "r". If ring chromosomes be distinguished clonally, an arabic number added after the "r" is used to distinguish between the different ring chromosomes. Their copy number precedes this symbol. Ring shaped marker chromosomes are always preceded by a plus sign ("+").

The ISCN manual does not describe a case with clonally distinguished rings with a copy number other than one; hence it is not really clear if the copy number of clonally distinguishable ring chromosomes has to follow the symbol, as with marker chromosomes.


  • +r: one additional ring chromosome is present
  • +3r: three additional ring chromosomes are present
  • +r1,+3r2: ring chromomes 1 and 2 can be distinguished clonally, with one copy of ring chromosome 1 and three copies of ring chromosome 2.
In order to understand all writing styles (also those not necessarily cancordant with the ISCN standard), the description string passed to the constructor of the Ring class is compared to the pattern "^((?<min>[\+\-]?\d*)([\-\~](?<max>\d+))?)?*x?rc?(?<num>\d+)?(x(?<min>\d+)([\-\~](?<max>\d+))?)?$" after removal of unnecessary spaces.

The "min" and "max" groups will catch the minimum and maximum copy number, resp., while the "num" group catches the number of a distinguishable ring chromosome.