Chromosome 18, Monosomy 18p

Important

It is possible that the main title of the report Chromosome 18, Monosomy 18p 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

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• Short Arm 18 Deletion Syndrome
• 18p Deletion Syndrome
• 18p- Syndrome
• Del(18p) Syndrome
• Monosomy 18p Syndrome

Disorder Subdivisions

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• None

General Discussion

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Chromosome 18, Monosomy 18p is a rare chromosomal disorder in which all or part of the short arm (p) of chromosome 18 is deleted (monosomic). The disorder is typically characterized by short stature, variable degrees of mental retardation, speech delays, malformations of the skull and facial (craniofacial) region, and/or additional physical abnormalities. Associated craniofacial defects may vary greatly in range and severity from case to case. However, such features commonly include an unusually small head (microcephaly); a broad, flat nose; a "carp-shaped" mouth; large, protruding ears; widely spaced eyes (ocular hypertelorism); and/or other abnormalities. Rarely (i.e., in about 10 percent of cases), Monosomy 18p may be associated with holoprosencephaly, a condition in which the forebrain (prosencephalon) fails to divide properly during embryonic development. Holoprosencephaly may result in varying degrees of mental retardation, other neurologic findings, and/or extremely variable midline facial defects, such as the presence of a single, central front tooth (maxillary incisor); closely spaced eyes (hypotelorism); an abnormal groove in the upper lip (cleft lip); incomplete closure of the roof of the mouth (cleft palate); and/or, in severe cases, absence of the nose and/or cyclopia. Cyclopia is characterized by fusion of the eye cavities (orbits) into a single cavity containing one eye.



In some individuals with Monosomy 18p, additional physical abnormalities may be present. Such findings commonly include a short, webbed neck; a broad chest with widely spaced nipples; relatively small hands and feet; and/or an unusually small penis (micropenis) and/or undescended testes (cryptorchidism) in affected males.



Monosomy 18p is usually caused by spontaneous (de novo) errors very early in the development of the embryo that appear to occur randomly for unknown reasons (sporadically).

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Resources

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Children's Craniofacial Association

13140 Coit Road

Suite 307

Dallas, TX 75240

USA

Tel: 2145709099

Fax: 2145708811

Tel: 8005353643

Email: csmith@ccakids.com

Internet: http://www.ccakids.com



Support Organization for Trisomy 18, 13, and Related Disorders

2982 South 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)428-7100

Fax: (914)997-4763

Tel: (888)663-4637

Email: Askus@marchofdimes.com

Internet: http://www.marchofdimes.com



The Arc (a national organization on mental retardation)

1010 Wayne Ave

Suite 650

Silver Spring, MD 20910

Tel: (301)565-3842

Fax: (301)565-3843

Tel: (800)433-5255

TDD: (817)277-0553

Email: info@thearc.org

Internet: http://www.thearc.org/



AboutFace USA

PO Box 158

South Beloit, IL 61080

USA

Tel: 8884861209

Email: info@AboutFaceUSA.org

Internet: http://www.aboutfaceusa.org



Chromosome Deletion Outreach, Inc.

P.O. Box 724

Boca Raton, FL 33429-0724

USA

Tel: 5613954252

Fax: 5613954252

Email: info@chromodisorder.org

Internet: http://www.chromodisorder.org



Chromosome 18 Registry & Research Society

7155 Oakridge Drive

San Antonio, TX 78229

Tel: (210)657-4968

Fax: (210)657-4968

Email: office@chromosome18.org

Internet: http://www.chromosome18.org



American Heart Association

National Center

7272 Greenville Avenue

Dallas, TX 75231-4596

Tel: (214)373-6300

Fax: (214)373-0268

Tel: (800)242-8721

Email: inquire@heart.org

Internet: http://www.americanheart.org



Craniofacial Foundation of America

975 East Third Street

Chattanooga, TN 37403

Tel: (423)778-9192

Fax: (423)778-8172

Tel: (800)418-3223

Email: farmertm@erlanger.org

Internet: http://www.craniofacialcenter.com



Independent Holoprosencephaly Support Site

Web Site on the Internet



Email: hpe@att.net

Internet: http://hpe.home.att.net



Holoprosencephaly Support Group

70 Ciphook Road

Linford

Bordon

Hertfordshire, Intl GU35 0PG

United Kingdom

Tel: (01420) 473-065

For a Complete Report

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This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site www.rarediseases.org or email orphan@rarediseases.org

Last Updated:   5/1/2003

Copyright   1989, 1990, 2001, 2003 National Organization for Rare Disorders, Inc.