The human body stores its genetic material in chromosomes. The number of chromosomes and the gene locus on the chromosome is unique to each species. Humans have 23 pairs of chromosomes, 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes that differentiate between males and females. All human chromosomes have 2 arms - the p(short) and the q(long) arm, which are separated by the centromeres. Telomeric ends There are two proposed mechanisms of forming the ring chromosome. One suggests that the chromosome 15 undergoes distortion on both p and q arms prior to the fusion of two broken arms, resulting great loss of genetic materials. Therefore, the patients of this type of r15 display severe clinical features. The other proposed mechanism suggests the direct fusion of two telomeres without losing any of the telomeric and subtelomeric sequences. Consequently, most of the genetic material is conserved and symptoms are expressed in a milder form, making diagnosis more difficult.
Ring chromosome 15
Ring chromosome 18
Ring chromosome 22
X chromosome
Y chromosome
Dup15q
Distal 18q-
Ethosome