$Unique_ID{BRK03849} $Pretitle{} $Title{Hypochondroplasia} $Subject{Hypochondroplasia Atypical Achondroplasia Achondroplasia Tarda Achondroplasia Kozlowski's Spondylometaphyseal Dysplasia } $Volume{} $Log{} Copyright (C) 1988, 1989 National Organization for Rare Disorders, Inc. 591: Hypochondroplasia ** IMPORTANT ** It is possible that the main title of the article (Hypochondroplasia) is not the name you expected. Please check the SYNONYM listing to find the alternate names and disorder subdivisions covered by this article. Synonyms Atypical Achondroplasia Achondroplasia Tarda Information on the following diseases can be found in the Related Disorders section of this report: Achondroplasia Kozlowski's Spondylometaphyseal Dysplasia General Discussion ** REMINDER ** The information contained in the Rare Disease Database is provided for educational purposes only. It should not be used for diagnostic or treatment purposes. If you wish to obtain more information about this disorder, please contact your personal physician and/or the agencies listed in the "Resources" section of this report. Hypochondroplasia is an inherited skeletal disorder. Major symptoms include dwarfism that does not become evident until mid-childhood. The disorder is characterized by a normal sized head and small but normally shaped hands and feet. Symptoms Hypochondroplasia can be distinguished from other forms of short limb dwarfism by examination of the bone structure of the skull and long bones of the arms and legs of affected children. The children appear normal at birth but the limbs fail to develop properly. The body thickens and is shorter than normal. The head is of normal size but the hands and feet are smaller than normal. The arms and legs are shorter than normal and are not usually bowed. There is limited flexibility in the elbows. Intelligence is usually normal, although motor development may be slowed. Causes Hypochondroplasia is inherited as an autosomal dominant trait. (Human traits including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother. In dominant disorders a single copy of the disease gene (received from either the mother or father) will be expressed "dominating" the other normal gene and resulting in appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is fifty percent for each pregnancy regardless of the sex of the resulting child.) Symptoms may develop due to failure of the limbs to grow normally. Affected Population Hypochondroplasia is a rare skeletal disorder that appears to affect females more often than males. Related Disorders Symptoms of the following disorders can be similar to those of Hypochondroplasia. Comparisons may be useful for a differential diagnosis: Achondroplasia is a form of short limbed dwarfism that is apparent at birth. It is characterized by bulging head, marked saddling of the nose and a certain facial characteristics. The body is shorter than normal with disproportioned arms and legs and thickened bones. Fingers that are very short and pudgy with "trident hands" and similar deformities of the toes and feet also occur. Other symptoms may include an abnormally curved back or spine and other abnormalities of the bone or cartilage. In some cases there are serious neurologic complications in early adulthood. (For more information on this disorder, choose "Achondroplasia " as your search term in the Rare Disease Database). Kozlowski's Spondylometaphyseal Dysplasia is characterized by reduced calcification of the bones, especially of the spine and pelvis. Onset is usually during the first year of life and is evident by the age two. It is an anterior deformity in the spine with limited growth and joint degeneration producing a waddling gait, short neck and trunk, bowed legs, pain and limited range of motion. This disorder affects both sexes equally. Therapies: Standard Treatment of Hypochondroplasia may consist of physical therapy or orthopedic corrections. Caesarean section deliveries may be necessary for patients who are pregnant. Genetic counseling may be of benefit for patients and their families. Other treatment is symptomatic and supportive. Therapies: Investigational This disease entry is based upon medical information available through November 1988. 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. Resources For more information on Hypochondroplasia, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 International Center for Skeletal Dysplasia St. Joseph Hospital 7620 York Road Towson, MD 21204 (301) 337-1250 The National Arthritis and Musculoskeletal and Skin Diseases (NIAMS) Information Clearinghouse Box AMS Bethesda, MD 20892 (301) 495-4484 The Magic Foundation 1327 N. Harlem Ave. Oak Park, IL 60302 (708) 383-0808 Human Growth Foundation (HGF) 7777 Leesburg Pike P.O. Box 3090 Falls Church, VA 22043 (703) 883-1773 (800) 451-6434 Parents of Dwarfed Children 11524 Colt Terrace Silver Spring, MD 20902 Little People of America P.O. Box 633 San Bruno, CA 94066 (415) 589-0695 Short Stature Foundation 17200 Jamboree Rd., Suite J Irvine, CA 92714-5828 (714) 474-4554 800-24 DWARF For Genetic Information and genetic counseling referrals: March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue White Plains, NY 10605 (914) 428-7100 Alliance of Genetic Support Groups 35 Wisconsin Circle, Suite 440 Chevy Chase, MD 20815 (800) 336-GENE (301) 652-5553 References MENDELIAN INHERITANCE IN MAN, 7th ed.: Victor A. McKusick; Johns Hopkins University Press, 1986. Pp. 408. HYPOCHONDROPLASIA, E.E. Specht, et al., Clin Orthop (July-August, 1975, issue (110)). Pp. 249-255. HYPOCHONDROPLASIA, D.E. Newman, et al., J Can Assoc Radiol (June, 1975, issue 26 (2)). Pp. 95-103. ACHONDROPLASIA AND HYPOCHONDROPLASIA. CLINICAL VARIATION AND SPINAL STENOSIS, R. Wynne-Davies, et al., J Bone Joint Surg [Br.] (1981, issue 63B (4)). 508-515.