Pyknodysostosis

Pyknodysostosis

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Pyknodysostosis 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

  • Pycnodysostosis
  • PKND
  • PYCD

Disorder Subdivisions

  • None

General Discussion

Pyknodysostosis is a rare disorder that is inherited as an autosomal recessive genetic trait. This disorder is characterized by short stature, increased bone density (osteosclerosis/osteopetrosis), underdevelopment of the tips of fingers with absent or small nails, fragile bones that may fracture easily, abnormal or absent collarbone (clavicle), and skull abnormalities with a protruding forehead and bulge on the back of the skull caused by delayed suture closure.

Symptoms

Pyknodysostosis is a rare disorder characterized by short stature and increased density of the bones. Individuals with this disorder typically have short arms and legs, an abnormal collarbone, and distinctive facial features including a large head with a small face, small chin, underdeveloped facial bones, a high forehead, high narrow palate and dental abnormalities. Bone fractures are common in individuals with pyknodysostosis. The small jaw may predispose affected individuals to periods of not breathing during sleep (obstructive sleep apnea).

Causes

The gene for PKND has been mapped to the same location as the gene for cathepsin K on chromosome 1q21. Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered. For example, "chromosome1q21" refers to band 21 on the long arm of chromosome 1. The numbered bands specify the location of the thousands of genes that are present on each chromosome.



Pyknodysostosis is a rare disorder that is inherited as an autosomal recessive genetic trait. Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.



Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.



All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Affected Populations

Pyknodysostosis is a very rare disorder that affects males and females in equal numbers. There have been approximately 133 cases of this disorder reported in the medical literature.

Standard Therapies

Diagnosis

The diagnosis of pyknodysostosis is based on physical features and X-ray findings. Molecular genetic testing is available to identify abnormalities in the cathepsin K gene.



Treatment

Individuals with pyknodysostosis will need orthopedic care when fractures occur. Appropriate dental care should be provided and craniofacial surgery may be warranted.

Treatment may be required to relieve the obstructive sleep apnea.



Genetic counseling may be of benefit for patients and their families. Other treatment 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 website.



For information about clinical trials being conducted at the National Institutes of Health (NIH) 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

Harris, M. Pyknodysostosis. In: The NORD Guide to Rare Disorders, Philadelphia: Lippincott, Williams and Wilkins, 2003:242-243.



Gorlin RJ, Cohen MM, Levin LS. Syndromes of the head and neck, 3rd ed. Oxford: Oxford University Press, 1990:285-287.



FROM THE INTERNET

McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore, MD: The Johns Hopkins University; Entry No. 265800; Last Update: 9/17/03.



JOURNAL ARTICLES

Gelb BD, Shi GP, Chapman, et al. Pycnodysostosis, a lysosomal disease caused by cathepsin K deficiency. Science 1996;273:1236-1238.



Hunt NP, Cunningham SJ Adnan N, et al. The dental, craniofacial, and biochemical features of pyknodysostosis: a report of three cases. L Oral Maxillofac Surg 1998;56:497-504.



Polymeropoulos MH, Ortiz De Luna RI, Ide SE, et al. The gene for pyknodysostosis maps to human chromosome 1cen-g21. Nature Genet. 1995;10:238-239.

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



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



NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases

Information Clearinghouse

One AMS Circle

Bethesda, MD 20892-3675

USA

Tel: (301)495-4484

Fax: (301)718-6366

Tel: (877)226-4267

TDD: (301)565-2966

Email: NIAMSinfo@mail.nih.gov

Internet: http://www.niams.nih.gov/



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/



Hide & Seek Foundation for Lysosomal Disease Research

6475 East Pacific Coast Highway Suite 466

Long Beach, CA 90803

Tel: (877)621-1122

Fax: (866)215-8850

Email: info@hideandseek.org

Internet: http://www.hideandseek.org



For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into myCigna.com. For non-Cigna members, 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.

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