Ring chromosome 18 is a genetic condition caused by a deletion of the two ends of chromosome 18 followed by the formation of a ring-shaped chromosome. It was first reported in 1964. Signs and symptoms
Ring 18 causes a wide range of medical and developmental concerns. As discussed above, people with ring 18 can have features of both distal 18q- and 18p-. The features of distal 18q- and 18p- vary greatly because of the variability of the deletion size and breakpoint locations between people. Because ring 18 can involve unique deletions of both the p and q arms of the chromosome there is twice as much reason for the variability between individuals. This variation is also partly attributable to the incidence of mosaicism, which is relatively common in people with ring 18. Holoprosencephaly has been reported in some people with ring 18. This is due to the deletion of the TGIF gene on the short arm of chromosome 18 in some people with ring 18. Approximately 30-40% of people with ring 18 have a congenital heart anomaly. Septal defects are the most common type of defect reported in this population. Hypotonia is frequently seen in the ring 18 population. Seizures, though uncommon, have been reported in people with ring 18. In some children without “classic” holoprosencephaly, microforms of holoprosencephaly may be noted on MRI, including missing olfactory tracts and bulbs and absent or hypoplastic corpus callosum. Strabismus as well as nystagmus have both been reported in infants and children with ring 18.
In the long term, physical therapy will be given to build strength in the muscles of the neck to increase stability and better protect the cervical spine. Collars, traction and surgery can be used to immobilize and stabilize the neck after a cervical fracture. Cervical collar
Minor fractures can be immobilized with a cervical collar without need for traction or surgery. A soft collar is fairly flexible and is the least limiting but can carry a high risk of further neck damage in patients with osteoporosis. It can be used for minor injuries or after healing has allowed the neck to become more stable. A range of manufactured rigid collars are also used, usually comprising a firm plastic bi-valved shell secured with Velcro straps and removable padded liners. The most frequently prescribed are the Aspen, Malibu, Miami J, and Philadelphia collars. All these can be used with additional chest and head extension pieces to increase stability. Rigid braces
Rigid braces that support the head and chest are also prescribed. Examples include the Sterno-Occipital Mandibular Immobilization Device (SOMI), Lerman Minerva and Yale types. Special patients, such as very young children or non-cooperative adults, are sometimes still immobilized in medical plaster of paris casts, such as the Minerva cast. Traction
Traction can be applied by free weights on a pulley or a halo type brace. The halo brace is the most rigid cervical brace, used when limiting motion to the minimum that is essential, especially with unstable cervical fractures.