Chromosome 18 ring
Overview
Chromosome 18 Ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 18 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
Symptoms
In most individuals, ring 18 changes the way the brain develops and works.
Infants, toddlers, and young children with ring 18 may develop more slowly than those without ring 18. For example, it may take a little longer for them to roll over, sit, crawl, and walk. It may also take longer for them to reach for and grab toys, hold a bottle, and to feed themselves. Language skills also develop later than their peers. Almost all children with ring 18 will require some type of therapy, such as speech, occupational, or physical therapy.
People with ring 18 usually have some cognitive disability, though the degree of impairment varies among individuals. Again, it is important to remember that every person with ring 18 is different. Some may be more severely affected than others. At this time, we cannot predict exactly how ring 18 will affect a child’s development.
Some people with ring 18 have a condition called holoprosencephaly. Holoprosencephaly is a type of birth defect in which the brain fails to divide into two separate halves during early embryonic development. This term includes a wide range of severity. In some babies, this condition is so severe that they do not survive in the womb or they may die shortly after birth.
Vision problems are often found in people with ring 18. Strabismus is fairly common in people with ring 18. Strabismus occurs when the movements of the eyes are not coordinated with one another. This is frequently referred to as being “cross-eyed”. Sometimes, people with ring 18 have nystagmus, or involuntary eye movements. Near-sightedness and far-sightedness also happen fairly frequently in people with ring 18.
For more information refer to chromosome 18 registry and research society.
Causes
Chromosome 18 Ring is usually caused by spontaneous (de novo) errors very early in the development of the embryo that appear to occur randomly for unknown reasons (sporadically).
Diagnosis
The signs and symptom information on this page attempts to provide a list of some possible signs and symptoms of Chromosome 18 Ring. This medical information about signs and symptoms for Chromosome 18 Ring has been gathered from various sources, may not be fully accurate, and may not be the full list of Chromosome 18 Ring signs or Chromosome 18 Ring symptoms. Furthermore, signs and symptoms of Chromosome 18 Ring may vary on an individual basis for each patient. Only your doctor can provide adequate diagnosis of any signs or symptoms and whether they are indeed Chromosome 18 Ring symptoms.
Prognosis
In general, if a person with Ring 18 is in good health with no major birth defects, there is no reason that they should not live to adulthood. In fact, within the Chromosome 18 Clinical Research Center, three out of the 25 study participants are over 18 years old. However, there have been at least two instances of premature death in a person with Ring 18. One child passed away at 4½ years due to lung failure. Unfortunately, no additional medical records are available for this individual. There was another young participant who died at 5 years old. Although the official cause of death is unknown, this child had a history of hydrocephalus and heart problems as well as breathing difficulties, all of which may have contributed to his death. It is important to remember that early death in this population is the exception rather than the rule.