Two major forms of thanatophoric dysplasia have been described, type I and type II. Type I thanatophoric dysplasia is distinguished by the presence of curved thigh bones and flattened bones of the spine (platyspondyly). Type II thanatophoric dysplasia is characterized by straight thigh bones and a moderate to severe skull abnormality called a cloverleaf skull.
The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
|Signs and Symptoms||Approximate number of patients (when available)|
|Abnormality of the femur||90%|
|Abnormality of the metaphyses||90%|
|Abnormality of the sacroiliac joint||90%|
|Aplasia/Hypoplasia of the lungs||90%|
|Bowing of the long bones||90%|
|Depressed nasal bridge||90%|
|Increased nuchal translucency||90%|
|Abnormality of neuronal migration||50%|
|Intrauterine growth retardation||50%|
|Abnormality of the kidney||7.5%|
|Atria septal defect||7.5%|
|Limitation of joint mobility||7.5%|
|Low-set, posteriorly rotated ears||7.5%|
|Patent ductus arteriosus||7.5%|
|Autosomal dominant inheritance||-|
|Decreased fetal movement||-|
|Intellectual disability, profound||-|
|Lethal short-limbed short stature||-|
|Severe short stature||-|
|Short long bone||-|
|Short sacroiliac notch||-|
|Small abnormally formed scapulae||-|
|Small foramen magnum||-|
|Wide-cupped costochondral junctions||-|
Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
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I was pregnant with twins who were diagnosed with thanatophoric dysplasia. What are the chances that I will have another pregnancy affected by this condition? See answer