Chromosome 22, Trisomy Mosaic

Chromosome 22, Trisomy Mosaic

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Chromosome 22, Trisomy Mosaic is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • Trisomy 22 Mosaic
  • Trisomy 22 Mosaicism Syndrome

Disorder Subdivisions

  • None

General Discussion

Chromosome 22, Trisomy Mosaic is a rare chromosomal disorder in which chromosome 22 appears three times (trisomy) rather than twice in some cells of the body. The term "mosaic" indicates that some cells contain the extra chromosome 22, whereas others have the normal chromosomal pair.



The range and severity of associated symptoms and findings may vary, depending upon the percentage of cells with the chromosomal abnormality. However, characteristic features typically include growth delays, mental retardation, unequal development of the two sides of the body (hemidystrophy), and webbing of the neck. Affected individuals may also have abnormal outward deviation of the elbows upon extension (cubitus valgus), multiple pigmented moles or birthmarks (nevi), distinctive malformations of the head and facial (craniofacial) area, and other physical abnormalities.

Symptoms

The symptoms and physical findings associated with Chromosome 22, Trisomy Mosaic may depend on the percentage of cells containing the extra 22nd chromosome. However, the disorder is often characterized by mental retardation, severe growth and developmental delays, and other physical abnormalities.



In many individuals with the disorder, there is unequal development of the two sides of the body (hemidystrophy), causing the body to appear dissimilar from one side to the other. For example, one leg may appear shorter than the other. In addition, in many individuals with hemidystrophy, there is associated hearing loss affecting one ear (unilateral hearing impairment).



According to reports in the medical literature, individuals with Chromosome 22, Trisomy Mosaic typically have additional symptoms and findings that are also often seen in Turner syndrome, another chromosomal disorder. (For further information on Turner syndrome, please see the "Related Disorders" section of this report below.) Such abnormalities include short stature; abnormal outward deviation of the elbows upon extension (cubitus valgus); multiple pigmented birthmarks (nevi); and malformations of the heart and its major blood vessels (cardiovascular defects), particularly defects affecting the major artery (aorta) that carries oxygen-rich blood from the lower left chamber (ventricle) of the heart throughout the body. Chromosome 22, Trisomy Mosaic is also associated with additional malformations seen in Turner syndrome, such as drooping of the upper eyelids (ptosis); webbing of the neck; a low hairline at the back of the neck; malformed (dysplastic) nails; and defective development of the ovaries (ovarian dysgenesis) in affected females. The ovaries are the paired glands that produce female reproductive cells (eggs) and certain female hormones. Therefore, ovarian dysgenesis may be associated with delayed or failed development of secondary sexual characteristics during puberty (e.g., breast development, the appearance of pubic hair, menstruation) and infertility.



Some individuals with Chromosome 22, Trisomy Mosaic also have additional malformations of the head and facial (craniofacial) area. In addition to drooping of the upper eyelids (ptosis), such malformations may include widely spaced eyes (ocular hypertelorism); vertical skin folds covering the eyes' inner corners (epicanthal folds); and abnormal pits or indentations in front of the ears (preauricular pits). Some affected individuals have additional physical abnormalities, such as underdeveloped fingers and toes (digits); abnormal skin creases on the palms of the hands; and kidney (renal) malformations.

Causes

In individuals with Chromosome 22, Trisomy Mosaic, chromosome 22 is present three times (trisomy) rather than twice in some cells of the body. 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".



The same chromosomal (karyotypical) makeup is usually present in all body cells (i.e., one cell line). However, those with a chromosomal mosaicism have two or more cell lines. Chromosome 22, Trisomy Mosaic is characterized by an extra chromosome 22 in one of an individual's cell lines, with at least one unaffected cell line also present. The presence of the additional chromosome is responsible for the symptoms and physical findings that characterize the disorder. Individuals with a low percentage of affected cells may have fewer, less severe symptoms than those with a high percentage of affected cells.



In most individuals with Chromosome 22, Trisomy Mosaic, the disorder appears to result from errors (e.g., nondisjunction) during the division of reproductive cells in one of the parents (parental meiosis) or during cellular division after fertilization (fetal mitosis). There have also been reports in which the disorder has occurred in association with uniparental disomy, an abnormality in which affected individuals have inherited both copies of a chromosomal pair from one parent, rather than one copy from each parent.

Affected Populations

Chromosome 22, Trisomy Mosaic appears to affect females more frequently than males. Approximately 15 cases have been reported in the medical literature.

Standard Therapies

Diagnosis

A diagnosis of Chromosome 22, Trisomy Mosaic may be suggested before birth (prenatally) by specialized tests, such as ultrasound, amniocentesis, or chorionic villus sampling (CVS). Fetal ultrasonography is a noninvasive diagnostic procedure during which reflected sound waves are used to create an image of the developing fetus. During amniocentesis, a sample of fluid that surrounds the fetus is removed and analyzed, whereas CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on the fluid or tissue samples may reveal the presence of Chromosome 22, Trisomy Mosaic.



Other testing may also sometimes be conducted to help confirm the diagnosis. For example, according to reports in the medical literature, fetal skin biopsy may be recommended in some cases in which mosaicism has been detected during amniocentesis. Fetal skin biopsy involves the removal and microscopic examination of certain cells (e.g., fibroblasts) from the developing fetus.



A diagnosis of Chromosome 22, Trisomy Mosaic may also be made or confirmed after birth (postnatally) based upon a thorough clinical evaluation, detection of characteristic physical findings, and chromosomal analysis. In addition, specialized testing may be conducted to detect or characterize certain abnormalities that may be associated with the disorder (e.g., hearing impairment, cardiovascular defects, renal abnormalities, ovarian dysgenesis, etc.).



Treatment

The treatment of Chromosome 22, Trisomy Mosaic 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; surgeons; physicians who diagnose and treat heart abnormalities (cardiologists); hearing specialists; and/or other health care professionals.



In some infants and children with Chromosome 22, Trisomy Mosaic, treatment may include the surgical repair of certain craniofacial, cardiovascular, or other abnormalities potentially associated with the disorder. The surgical procedures performed will depend upon the severity of the anatomical abnormalities, their associated symptoms, and other factors. In addition, for some individuals with unilateral hearing loss, the use of artificial devices (prostheses) may be recommended, such as specialized hearing aids. Other treatment for the disorder is symptomatic and supportive.



Early intervention may be important in ensuring that children with Chromosome 22, Trisomy Mosaic reach their potential. Special services that may be beneficial include special education, speech therapy, physical therapy, and/or other medical, social, and/or vocational services. Genetic counseling will also be of benefit for affected individuals and their families.

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

References

TEXTBOOKS

Buyse ML. Birth Defects Encyclopedia. Dover, MA: Blackwell Scientific Publications, Inc.; 1990:395, 1717-1719.



JOURNAL ARTICLES

Berghella V, et al. Prenatal confirmation of true fetal trisomy 22 mosaicism by fetal skin biopsy following normal fetal blood sampling. Prenat Diagn. 1998;18:384-389.



Crowe CA, et al. Mosaic trisomy 22: a case presentation and literature review of trisomy 22 phenotypes. Am J Med Genet. 1997;71:406-413. Comment in: Am J Med Genet. 1998;76:447.



Hirschhorn K. Mosaic trisomy 22: a case presentation and literature review of trisomy 22 phenotypes [letter]. Am J Med Genet. 1998;76:447. Comment on: Am J Med Genet. 1997;71:406-413.



Stoll C, et al. De novo trisomy 22 due to an extra 22Q-chromosome. Ann Genet. 1997;40:217-221.



de Pater JM, et al. Maternal uniparental disomy for chromosome 22 in a child with generalized mosaicism for trisomy 22. Prenat Diagn. 1997;17:81-86.



Phillips OP, et al. Risk of fetal mosaicism when placental mosaicism is diagnosed by chorionic villus sampling. Am J Obstet Gynecol. 1996;174:850-855.



Bacino CA, et al. Clinical and molecular studies in full trisomy 22: further delineation of the phenotype and review of the literature. Am J Med Genet. 1995;56:359-365. Comment in: Am J Med Genet. 1996;62:98-99, 100-101.



Robinson WP, et al. Mosaicism most likely accounts for extended survival of trisomy 22 [letter]. Am J Med Genet. 1996;62:100-101. Comment on: Am J Med Genet. 1995;56:359-365.



Woods CG, et al. Asymmetry and skin pigmentary anomalies in chromosome mosaicism. J Med Genet. 1994;31:694-701.



Lund HT, et al. Trisomy 22 mosaicism limited to skin fibroblasts in a mentally retarded, dysmorphic girl. Acta Paediatr Scand. 1990;79:714-718.



Lessick ML, et al. Trisomy 22 mosaicism with normal blood chromosomes. Case report with literature review. Clin Pediatr. 1988;27:451-454.



Wertelecki W, et al. Trisomy 22 mosaicism syndrome and Ullrich-Turner stigmata. Am J Med Genet. 1986;23:739-749.



Schinzel A, et al. Incomplete trisomy 22. III. Mosaic trisomy 22 and the problem of full trisomy 22. Hum Genet. 1981;56:269-273.



Dulitzky F, et al. Unilateral radial aplasia and trisomy 22 mosaicism. J Med Genet. 1981;18:473-476.



A. Schinzel, et al.;Incomplete trisomy 22. III .Mosaic trisomy 22 and the problem of full trisomy 22. Hum Genet 1981; 56(3):269-273.



Unilateral radial aplasia and trisomy 22 mosaicism.. F. Dulitzky,et al.; J Med Genet (Dec 1981; 18(6)). Pp. 473-476.



Shokeir MH. Complete trisomy 22. Clin Genet. 1978;14:139-146.

Resources

Support Organization for Trisomy 18, 13, and Related Disorders

2982 S. Union Street

Rochester, NY 14624-1926

Fax: (585)594-1957

Tel: (800)716-7638

Email: barbv@trisomy.org

Internet: http://www.trisomy.org



March of Dimes Birth Defects Foundation

1275 Mamaroneck Avenue

White Plains, NY 10605

Tel: (914)997-4488

Fax: (914)997-4763

Tel: (888)663-4637

Email: Askus@marchofdimes.com

Internet: http://www.marchofdimes.com



The Arc

1825 K Street NW, Suite 1200

Washington, DC 20006

Tel: (202)534-3700

Fax: (202)534-3731

Tel: (800)433-5255

TDD: (817)277-0553

Email: info@thearc.org

Internet: http://www.thearc.org



American Heart Association

7272 Greenville Avenue

Dallas, TX 75231

Tel: (214)784-7212

Fax: (214)784-1307

Tel: (800)242-8721

Email: Review.personal.info@heart.org

Internet: http://www.heart.org



Support Organization for Trisomy 13/18 and Related Disorders, UK

c/o Christine Rose

48 Froggatts Ride

Walmley

Sutton Coldfield

West Midlands, B76 2TQ SOFT

United Kingdom

Tel: 01213513122

Email: enquiries@soft.org.uk

Internet: http://www.soft.org.uk



UNIQUE - Rare Chromosome Disorder Support Group

P.O. Box 2189

Caterham

Surrey, CR3 5GN

United Kingdom

Tel: 4401883330766

Fax: 4401883330766

Email: info@rarechromo.org

Internet: http://www.rarechromo.org



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/



For a Complete Report

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