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.[1]
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 metaphysis | Very frequent (present in 80%-99% of cases) |
| Disproportionate short-limb |
Very frequent (present in 80%-99% of cases) |
| Flat face | Very frequent (present in 80%-99% of cases) |
| Increased nuchal translucency | Very frequent (present in 80%-99% of cases) |
| Very frequent (present in 80%-99% of cases) |
|
| Macrocephaly | Very frequent (present in 80%-99% of cases) |
| Micromelia | Very frequent (present in 80%-99% of cases) |
| Muscular |
Very frequent (present in 80%-99% of cases) |
| Narrow chest | Very frequent (present in 80%-99% of cases) |
| Platyspondyly | Very frequent (present in 80%-99% of cases) |
| Pulmonary hypoplasia | Very frequent (present in 80%-99% of cases) |
| Redundant skin | Very frequent (present in 80%-99% of cases) |
| Short thorax | Very frequent (present in 80%-99% of cases) |
| Skeletal dysplasia | Very frequent (present in 80%-99% of cases) |
| Frequent (present in 30%-79% of cases) |
|
| Frontal bossing | Frequent (present in 30%-79% of cases) |
| Hearing impairment | Frequent (present in 30%-79% of cases) |
| Heterotopia | Frequent (present in 30%-79% of cases) |
| Intrauterine growth retardation | Frequent (present in 30%-79% of cases) |
| Midface retrusion | Frequent (present in 30%-79% of cases) |
| Proptosis | Frequent (present in 30%-79% of cases) |
| Ventriculomegaly | Frequent (present in 30%-79% of cases) |
| Abnormality of the kidney | Occasional (present in 5%-29% of cases) |
| Abnormality of the sacroiliac joint | Occasional (present in 5%-29% of cases) |
| Occasional (present in 5%-29% of cases) |
|
| Atrial septal defect | Occasional (present in 5%-29% of cases) |
| Cloverleaf skull | Occasional (present in 5%-29% of cases) |
| Downslanted palpebral fissures | Occasional (present in 5%-29% of cases) |
| Hip dysplasia | Occasional (present in 5%-29% of cases) |
| Occasional (present in 5%-29% of cases) |
|
| Joint hyperflexibility | Occasional (present in 5%-29% of cases) |
| Joint stiffness | Occasional (present in 5%-29% of cases) |
| Kyphosis | Occasional (present in 5%-29% of cases) |
| Low-set ears | Occasional (present in 5%-29% of cases) |
| Patent ductus arteriosus | Occasional (present in 5%-29% of cases) |
| Polyhydramnios | Occasional (present in 5%-29% of cases) |
| Respiratory insufficiency | Occasional (present in 5%-29% of cases) |
| Occasional (present in 5%-29% of cases) |
|
| - | |
| Bowing of the long bones | - |
| Decreased fetal movement | - |
| Flared metaphysis | - |
| Hypoplastic ilia | - |
| Lethal short-limbed short stature | - |
| Metaphyseal irregularity | - |
| Neonatal death | - |
| Severe platyspondyly | - |
| Severe short stature | - |
| Short long bone | - |
| Short ribs | - |
| Short sacroiliac notch | - |
| Small abnormally formed scapulae | - |
| Small face | - |
| 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.
The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your 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
