Ring chromosome 18 syndrome

Ring chromosome 18 syndrome (also known as r(18) syndrome or ring 18) is a rare chromosomal disorder in which both ends of chromosome 18 are deleted and the remaining chromosome forms a circular (ring) structure. The clinical presentation is highly variable and depends on the amount of genetic material lost from the short arm (18p) and long arm (18q) of chromosome 18. Because the condition combines features of both 18p deletion syndrome and 18q deletion syndrome, affected individuals may exhibit a wide spectrum of signs and symptoms. Common clinical features include intellectual disability of variable severity, short stature, microcephaly, facial dysmorphism (such as a flat midface, epicanthal folds, downturned corners of the mouth, and a broad or flat nasal bridge), and hypotonia. Growth retardation is frequently observed, both prenatally and postnatally. Hearing loss (particularly sensorineural), limb anomalies, and genital abnormalities may also occur. Some individuals develop seizures. Immune deficiency, particularly IgA deficiency, has been reported in cases with significant 18q deletions. Congenital heart defects and other organ malformations may be present in some patients. There is no cure for ring chromosome 18 syndrome, and management is supportive and symptom-based. Treatment may include early intervention programs, speech and physical therapy, special education services, hearing aids or cochlear implants for hearing loss, growth hormone therapy for short stature, antiepileptic medications for seizures, and surgical correction of congenital anomalies when indicated. Regular monitoring by a multidisciplinary team including geneticists, neurologists, endocrinologists, and audiologists is recommended. The Chromosome 18 Registry and Research Society serves as a key resource for affected families.

Common questions about Ring chromosome 18 syndrome