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Tetra-amelia syndrome is a very rare disorder characterized by the absence of all four limbs. ("Tetra" is the Greek word for "four," and "amelia" refers to the failure of an arm or leg to develop before birth.) This syndrome can also cause severe malformations of other parts of the body, including the face and head, heart, nervous system, skeleton, and genitalia. The lungs are underdeveloped in many cases, which makes breathing difficult or impossible. Because children with tetra-amelia syndrome have such serious medical problems, most are stillborn or die shortly after birth.
Tetra-amelia syndrome has been reported in only a few families worldwide.
Researchers have found a mutation in the WNT3 gene in people with tetra-amelia syndrome from one large family. This gene is part of a family of WNT genes that play critical roles in development before birth. The protein produced from the WNT3 gene is involved in the formation of the limbs and other body systems during embryonic development. Mutations in the WNT3 gene prevent cells from producing functional WNT3 protein, which disrupts normal limb formation and leads to the other serious birth defects associated with tetra-amelia syndrome.
In other affected families, the cause of tetra-amelia syndrome has not been determined. Researchers believe that unidentified mutations in WNT3 or other genes involved in limb development are probably responsible for the disorder in these cases.
Changes in this gene are associated with tetra-amelia syndrome.
In most of the families reported so far, tetra-amelia syndrome appears to have an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means both copies of the gene in each cell have mutations. The parents of an individual with tetra-amelia syndrome each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.
These resources address the diagnosis or management of tetra-amelia syndrome and may include treatment providers.
You might also find information on the diagnosis or management of tetra-amelia syndrome in Educational resources (http://www.ghr.nlm.nih.gov/condition/tetra-amelia-syndrome/show/Educational+resources) and Patient support (http://www.ghr.nlm.nih.gov/condition/tetra-amelia-syndrome/show/Patient+support).
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.
You may find the following resources about tetra-amelia syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).
amelia ; autosomal ; autosomal recessive ; cell ; embryonic ; gene ; genitalia ; inheritance ; mutation ; nervous system ; pattern of inheritance ; protein ; recessive ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.