<unk>  (sometimes denoted as r15) is a condition that arises when chromosome<unk>  fuses to form a ring chromosome. Usually, r15 forms due to modifications or deletion of genes on chromosome<unk>  in the preliminary stages of embryonic development but it can rarely also be inherited. If the ends of the chromosome fuse with no loss of genetic material, the individual retains the normal phenotype with relatively slight difference. However, when there is deletion of genetic information at the distal unstable ends where the subtelomeric structures fuse, syndromes associated with that particular chromosome arise. All chromosomes have the capacity to form such rings; the symptoms and severity depend on the amount of the genetic information lost. Thus, the treatment for r15 predominantly targets the eradication of these symptoms rather than the chromosome ring itself.
Ring chromosome 15
Ring chromosome 18
Ring chromosome 22
X chromosome
Y chromosome
Dup15q
Distal 18q-
Ethosome