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Chromosome 14 Ring

The information in NORD’s Rare Disease Database is for educational purposes only. It should never be used for diagnostic or treatment purposes. If you have questions regarding a medical condition, always seek the advice of your physician or other qualified health professional. NORD’s reports provide a brief overview of rare diseases. For more specific information, we encourage you to contact your personal physician or the agencies listed as “Resources” on this report.

Copyright 1993, 1994, 2000, 2001, 2002, 2003, 2004, 2009

NORD is very grateful to Shashikant Kulkarni, PhD, Director of CytoGenomics and Molecular Pathology, Director of Clinical & Molecular Cytogenetics, Department of Pathology, Washington University School of Medicine, for assistance in the preparation of this report.

Synonyms of Chromosome 14 Ring

Disorder Subdivisions

General Discussion

Chromosome 14 Ring is a rare disorder that is characterized by abnormalities of the 14th chromosome. Affected infants and children typically have delays in the acquisition of skills that require the coordination of physical and mental activities (psychomotor delays), mental retardation, growth delays, and episodes of uncontrolled electrical activity in the brain (seizures). The disorder is also characterized by distinctive abnormalities of the head and facial (craniofacial) area. Such abnormalities may include an unusually small head (microcephaly) with a high forehead; an elongated face; widely spaced eyes (ocular hypertelorism); a thin upper lip; a flat nasal bridge with a prominent nasal tip; and large, low-set ears.

Symptoms

The symptoms and findings associated with Chromosome 14 Ring may vary in range and severity from case to case. However, in many individuals with the disorder, such abnormalities may include growth delays before and after birth (prenatal and postnatal growth retardation), diminished muscle tone (hypotonia), feeding difficulties during infancy, psychomotor delays, and mental retardation. In addition, recurrent seizures (epilepsy) typically develop beginning during infancy or early childhood. The specific form a seizure takes and its associated symptoms may vary, depending upon the region(s) of the brain affected and other factors. For example, seizure episodes may be characterized by shock-like contractions of certain muscles or muscle groups (myoclonic seizures); increased stiffness (rigidity) and rapid, rhythmic contraction and relaxation of certain muscle groups (tonic-clonic seizures); sensory or behavioral disturbances; lost consciousness; and/or impaired control of certain voluntary functions, such as bowel or bladder control. (For more information, please choose "epilepsy" as your search term in the Rare Disease Database.)

Individuals with Chromosome 14 Ring may also have characteristic abnormalities of the head and facial (craniofacial) area, resulting in a distinctive facial appearance. These abnormalities may include a small head (microcephaly) with a high forehead; an elongated face; and a flat nasal bridge with a prominent nasal tip and slightly upturned nostrils (anteverted nares). The eyes may be widely spaced (ocular hypertelorism) with downwardly slanting eyelid folds (palpebral fissures) and vertical skin folds covering the eyes' inner corners (epicanthic folds). Affected individuals may also have additional characteristic features, such as a thin upper lip; downwardly turned corners of the mouth; a highly arched roof of the mouth (palate); an unusually small jaw (micrognathia); and large, low-set ears.

Chromosome 14 Ring may also be characterized by other physical abnormalities, including a short neck with excessive skin folds; abnormal skin ridge patterns (dermatoglyphics), such as the presence of a single crease across the palm (simian crease); widely spaced nipples; and abnormalities of skin coloration (pigmentation). These may include vitiligo, a chronic condition in which patches of skin lose pigmentation, or the presence of cafe-au-lait spots, which are light brown or pale tan discolorations of the skin. (For more information, please choose "vitiligo" as your search term in the Rare Disease Database.) Some affected individuals may also have abnormalities of the nerve-rich membrane that forms the innermost region of the eye (retina), such as abnormalities of retinal pigmentation.

In some cases, certain additional abnormalities may also be associated with Chromosome 14 Ring. For example, in addition to seizures, other neurological symptoms may sometimes be present, such as an impaired ability to coordinate voluntary movements (ataxia) or rhythmic involuntary movements of a part or parts of the body (tremor) that occur or may increase with certain goal-directed voluntary actions (intention tremor). In addition, in some affected individuals, certain joints may become permanently flexed or extended in fixed postures (joint contractures). Abnormalities of the heart may also be present at birth (congenital heart defects), such as narrowing (stenosis) of the major artery that carries oxygenated blood to the body (aorta) or the artery that transports oxygen-depleted blood to the lungs (pulmonary artery). Individuals with Chromosome 14 Ring may also be susceptible to repeated respiratory infections.

Causes

Chromosome 14 Ring results from loss (deletion) of genetic material from both ends of the 14th chromosome and joining of the ends to form a ring. Associated symptoms and findings may vary, depending upon the amount of genetic material lost from the 14th chromosome or the stability of the ring chromosome during subsequent cellular divisions (i.e., mitosis). Evidence suggests that features associated with Chromosome 14 Ring may result from relatively small deletions of genetic material from the long arm (q) of chromosome 14 (14q).

Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as "p" and a long arm identified by the letter "q." Chromosomes are further subdivided into bands that are numbered.

Chromosome 14 Ring usually appears to be caused by spontaneous or "de novo" errors early during the development of the embryo. The parents of an affected child typically have normal chromosomes, and the probability of having another child with the chromosomal abnormality is low. However, when a parent of the affected individual has Chromosome 14 Ring, the chances are greater of having another child with this chromosomal abnormality.

Affected Populations

Chromosome 14 Ring is an extremely rare chromosomal disorder that has appeared to affect males slightly more often than females. There have been over 40 cases reported in the medical literature.

Related Disorders

Additional chromosomal disorders may have features similar to those associated with Chromosome 14 Ring. Chromosomal testing is necessary to confirm the specific chromosomal abnormality present. (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use "chromosome" as your search term in the Rare Disease Database.)

Standard Therapies

Diagnosis
In some cases, a diagnosis of Chromosome 14 Ring may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Chromosome 14 Ring.

The diagnosis of Chromosome 14 Ring may be confirmed after birth (postnatally) based upon a thorough clinical evaluation, characteristic physical findings, and chromosomal analysis. Specialized testing may also be conducted to detect certain findings that may be associated with the disorder. Such testing may include electroencephalography (EEG) and computerized tomography (CT) scanning or magnetic resonance imaging (MRI) of the brain. An EEG is a noninvasive diagnostic technique that records the brain's electrical activity. During CT scanning, a computer and x-rays are used to create a film showing cross-sectional images of the brain's tissue structure. During MRI, a magnetic field and radio waves form detailed cross-sectional images of the brain.

Treatment
The treatment of Chromosome 14 Ring is directed toward the specific symptoms that are apparent in each individual. Such treatment may require the coordinated efforts of a team of medical professionals, such as pediatricians; physicians who specialize in neurological disorders (neurologists); heart specialists (cardiologists); physicians who diagnose and treat disorders of the skeleton, muscles, joints, and related tissues (orthopedists); physical therapists; and/or other health care professionals.

In some cases, treatment with antiseizure (anticonvulsant) drugs may help prevent, reduce, or control seizures associated with Chromosome 14 Ring. The specific medication used may depend upon the form of seizures present and other factors. In some affected individuals, seizures may be difficult to control (refractory). In such cases, recommended treatment may include combining certain appropriate anticonvulsant drugs.

The treatment of individuals with Chromosome 14 Ring may also include measures to help prevent or aggressively treat respiratory infections. In addition, orthopedic measures and physical therapy may be recommended to help prevent or correct contracture development. In individuals with congenital heart defects, treatment with certain medications, surgical intervention, and/or other measures may be required. The surgical procedures performed may depend upon the location and severity of the abnormalities, their associated symptoms, and other factors.

Early intervention may also be important in ensuring that affected children reach their potential. Special services that may be beneficial include special education and other medical, social, and/or other services.

Genetic counseling will also be of benefit for individuals with Chromosome 14 Ring and their families. Other treatment for this disorder is symptomatic and supportive.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com

Chromosome 14 Ring Resources

NORD Member Organizations:

(To become a member of NORD, an organization must meet established criteria and be approved by the NORD Board of Directors. If you're interested in becoming a member, please contact Susan Olivo, Membership Manager, at solivo@rarediseases.org.)

Other Organizations:

References

TEXTBOOKS
Behrman RE, et al., eds. Nelson Textbook of Pediatrics. 15th ed. Philadelphia, PA: W.B. Saunders Company; 1996:317.

Buyse ML. Birth Defects Encyclopedia. Dover, MA: Blackwell Scientific Publications, Inc.; 1990:372-73.

JOURNAL ARTICLES
Hisatomi T, et al. A case of ring 14 chromosome with ocular manifestations. Nippon Ganka Gakkai Zasshi. 2000;104:121-24.

Ning Y, et al. Prenatal diagnosis of a mosaic extra structurally abnormal chromosome by spectral karyotyping. Prenat Diagn. 1999;19:480-82.

Ono J, et al. Ring chromosome 14 complicated with complex partial seizures and hypoplastic corpus callosum. Pediatr Neurol. 1999;20:70-72.

Campos Tristan C, et al. Ring chromosome 14: report of a new case. An Esp Pediatr. 1998;48:650-52.

Wintle RF, et al. Molecular analysis redefines three human chromosome 14 deletions. Hum Genet. 1995;95:495-500.

Midro AT, et al. Epilepsy in a child with ring chromosome 14. Neurol Neurochir Pol. 1993;27:99-104.

Kristensen I, et al. The ring chromosome 14 syndrome. Ugeskr Laeger. 1992;154:3248-49.

Shirasaka Y, et al. Ring 14 chromosome with complex partial seizures: a case report. Brain Dev. 1992;14:257-60.

Rudenskaia GE, et al. Ring chromosome 14. Pediatriia. 1992;66-69.

Zelante L, et al. Ring chromosome 14 syndrome. Report of two cases, including extended evaluation of a previously reported patient and review. Ann Genet. 1991;34:93-97.

Matalon R, et al. Transmission of ring 14 chromosome from mother to two sons. Am J Med Genet. 1990;36:381-85.

de Blois MC, et al. r14 syndrome without major dysmorphism. Ann Genet. 1990;33:155-58.

Cantu ES, et al. Unusual cytogenetic mosaicism involving chromosome 14 abnormalities in a child with an MR/MCA syndrome and abnormal pigmentation. Clin Genet. 1989;36:189-95.

Duarte MH, et al. Epilepsy in ring chromosome 14 syndrome. Arq Neuropsiquiatr. 1989;47:205-11.

Keyeux G, et al. Molecular characterization of a ring chromosome 14 showing that the PI locus is centromeric to the D14S1 and IGH loci. Hum Genet. 1989;82:219-22.

Portoian-Shuhaiber S, et al. Clinical findings in an Arab boy with ring (14)(mos 46,XY,r(14)/45,XY,-14). Ann Genet. 1986;29:122-24.

Fryns JP, et al. Ring chromosome 14. A distinct clinical entity. J Genet Hum. 1983;31:367-75.

Fryns JP, et al. Ring chromosome 14 syndrome. Ann Genet. 1982;25:179-80.

Report last updated: 2009/04/10 00:00:00 GMT+0