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Because the ends break off, genetic information is lost. Rings can also form without the ends breaking off, and the p arm and the q arm just 'stick' together, without any apparent loss of genetic material. Sometimes, the rings (regardless of how they are formed) cause problems in the baby's development. This is because the ring interferes with cell division and can cause genes to not work properly because they are rearranged.
Ring chromosomes do not always cause health problems or delays in development. It depends on the size of the ring, how much genetic material was lost, and which chromosomes are involved. If a ring chromosome is found in a child, the parents' chromosomes are studied to determine whether the ring was inherited or not. If one parent has the ring chromosome, then the physician knows that the baby inherited the ring from that parent. If the parent is normal and healthy, it is thought that the ring did not cause any harm to the genes when the ring chromosome formed. (The parents' other relatives may also have inherited the ring chromosome and should have the option of having their chromosomes studied). However, if the ring is not present in one of the parents, there is a chance that some of the genetic material may have been lost or altered in the rearrangement. This could cause problems in the baby's development, including birth defects.
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Chromosome Arrangements: Rings and Inversions
