Description
Ring chromosome 14 syndrome is a condition that is characterized by seizures and intellectual disabilities. In people with ring chromosome 14 syndrome, recurrent seizures (epilepsy) develop during infancy or early childhood. In many cases, these seizures are resistant to treatment with antiseizure medications. Intellectual disabilities are common in people with ring chromosome 14 syndrome and usually range from moderate to severe. In addition, the development of speech and motor skills (such as sitting, standing, and walking) are typically delayed
Some people with ring chromosome 14 syndrome also have behavioral problems, such as hyperactivity or features of autism spectrum disorder, which is characterized by impaired communication and social interaction.
Additional features of ring chromosome 14 syndrome may include:
- Weak muscle tone (hypotonia)
- Slow growth and short stature
- Unusually small head size (microcephaly
) - Puffy hands and/or feet caused by a buildup of fluid (lymphedema)
- Subtle differences in facial features
- Recurring infections, especially respiratory infections
- Digestive problems and nutritional deficiencies
Various eye abnormalities can be associated with ring chromosome 14 syndrome. These include eyes that do not look in the same direction (strabismus
), a clouding of the lenses of the eyes (cataracts
), and abnormalities of the specialized tissue at the back of the eye that detects light and color (retina
).
Frequency
Because ring chromosome 14 syndrome appears to be extremely rare, its exact prevalence is unknown. More than 80 affected individuals have been reported in the scientific literature.
Causes
Ring chromosome 14 syndrome is caused by a rearrangement of chromosome 14 called ring chromosome 14, sometimes written as r(14). A ring chromosome
is a circular structure that occurs when a chromosome breaks in two places and the broken ends fuse together.
Several critical genes near the end of the long (q) arm of chromosome 14 may be lost when the ring chromosome forms. The loss of these genes on one of the two copies of chromosome 14 likely contributes to several of the major features of ring chromosome 14 syndrome, including the intellectual disabilities and developmental delays. In addition, chromosomal rearrangements can disrupt several mechanisms that are involved in the regulation of gene activity (expression), which may also contribute to the features seen in people with ring chromosome 14 syndrome.
Inheritance
Ring chromosome 14 syndrome is typically not inherited. A ring chromosome usually occurs as a random event during the formation of reproductive cells (eggs or sperm) or during early embryonic development. In some cases, the ring chromosome is present in only some of a person's cells. This situation is known as mosaicism
.
Although most affected individuals have no history of the disorder in their families, there are reports of a ring chromosome being passed from a parent to a child in at least two families.
Other Names for This Condition
- Ring 14
- Ring 14 syndrome
- Ring chromosome 14
Additional Information & Resources
Genetic Testing Information
Genetic and Rare Diseases Information Center
Patient Support and Advocacy Resources
Catalog of Genes and Diseases from OMIM
Scientific Articles on PubMed
References
- Gardner JA, Haslett N, Giguere HG, Anderson KJ. Ring Chromosome 14 with a Terminal 14q32.33 Deletion. J Assoc Genet Technol. 2024;50(2):69-73. Citation on PubMed
- Giovannini S, Marangio L, Fusco C, Scarano A, Frattini D, Della Giustina E, Zollino M, Neri G, Gobbi G. Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients. Epilepsia. 2013 Dec;54(12):2204-13. doi: 10.1111/epi.12393. Epub 2013 Oct 1. Citation on PubMed
- Morimoto M, Usuku T, Tanaka M, Otabe O, Nishimura A, Ochi M, Takeuchi Y, Yoshioka H, Sugimoto T. Ring chromosome 14 with localization-related epilepsy: three cases. Epilepsia. 2003 Sep;44(9):1245-9. doi: 10.1046/j.1528-1157.2003.05403.x. Citation on PubMed
- Rinaldi B, Vaisfeld A, Amarri S, Baldo C, Gobbi G, Magini P, Melli E, Neri G, Novara F, Pippucci T, Rizzi R, Soresina A, Zampini L, Zuffardi O, Crimi M. Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force. Orphanet J Rare Dis. 2017 Apr 11;12(1):69. doi: 10.1186/s13023-017-0606-4. Citation on PubMed
- Schlade-Bartusiak K, Costa T, Summers AM, Nowaczyk MJ, Cox DW. FISH-mapping of telomeric 14q32 deletions: search for the cause of seizures. Am J Med Genet A. 2005 Oct 15;138A(3):218-24. doi: 10.1002/ajmg.a.30942. Citation on PubMed
- Specchio N, Trivisano M, Serino D, Cappelletti S, Carotenuto A, Claps D, Marras CE, Fusco L, Elia M, Vigevano F. Epilepsy in ring 14 chromosome syndrome. Epilepsy Behav. 2012 Dec;25(4):585-92. doi: 10.1016/j.yebeh.2012.09.032. Epub 2012 Nov 14. Citation on PubMed
- Unique: Ring 14
- Vaisfeld A, Spartano S, Gobbi G, Vezzani A, Neri G. Chromosome 14 deletions, rings, and epilepsy genes: A riddle wrapped in a mystery inside an enigma. Epilepsia. 2021 Jan;62(1):25-40. doi: 10.1111/epi.16754. Epub 2020 Nov 17. Citation on PubMed
- van Karnebeek CD, Quik S, Sluijter S, Hulsbeek MM, Hoovers JM, Hennekam RC. Further delineation of the chromosome 14q terminal deletion syndrome. Am J Med Genet. 2002 Jun 1;110(1):65-72. doi: 10.1002/ajmg.10207. Citation on PubMed
- Zollino M, Ponzi E, Gobbi G, Neri G. The ring 14 syndrome. Eur J Med Genet. 2012 May;55(5):374-80. doi: 10.1016/j.ejmg.2012.03.009. Epub 2012 Apr 14. Citation on PubMed
- Zollino M, Seminara L, Orteschi D, Gobbi G, Giovannini S, Della Giustina E, Frattini D, Scarano A, Neri G. The ring 14 syndrome: clinical and molecular definition. Am J Med Genet A. 2009 Jun;149A(6):1116-24. doi: 10.1002/ajmg.a.32831. Citation on PubMed
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