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    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

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

    Disorder Subdivisions

    • None

    General Discussion

    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).

    Resources

    Children's Craniofacial Association
    13140 Coit Road
    Suite 517
    Dallas, TX 75240
    USA
    Tel: (214)570-9099
    Fax: (214)570-8811
    Tel: (800)535-3643
    Email: contactCCA@ccakids.com
    Internet: http://www.ccakids.com

    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

    AmeriFace
    P.O. Box 751112
    Limekiln, PA 19535
    USA
    Tel: (702)769-9264
    Fax: (702)341-5351
    Tel: (888)486-1209
    Email: info@ameriface.org
    Internet: http://www.ameriface.org

    Chromosome Disorder Outreach, Inc.
    P.O. Box 724
    Boca Raton, FL 33429-0724
    USA
    Tel: (561)395-4252
    Fax: (561)395-4252
    Email: info@chromodisorder.org
    Internet: http://www.chromodisorder.org/CDO/

    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
    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

    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

    Craniofacial Foundation of America
    975 East Third Street
    Chattanooga, TN 37403
    Tel: (423)778-9176
    Fax: (423)778-8172
    Tel: (800)418-3223
    Email: terry.smyth@erlanger.org
    Internet: http://www.craniofacialfoundation.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:

    This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".

    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: 4/10/2009
    Copyright 1989, 1990, 2001, 2003, 2009 National Organization for Rare Disorders, Inc.

    WebMD Medical Reference from the National Organization for Rare Disorders

    Last Updated: May 28, 2015
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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