| Hanhart syndrome | |
|---|---|
 | |
| An infant with Möbius syndrome and Oromandibular-limb hypogenesis syndrome, exhibiting similar symptoms to Hanhart syndrome | |
| Symptoms | Underdevelopment of the mouth, jaw, tongue, and extremities |
| Usual onset | Neonatal, antenatal |
| Duration | Lifelong |
| Causes | Vascular disruption during fetal development |
| Differential diagnosis | Nager acrofacial dysostosis Goldenhar syndrome |
| Frequency | <1/1,000,000, 30 known cases |
Hanhart syndrome[a] is a broadly classified medical condition consisting of congenital disorders that cause an undeveloped tongue and malformed extremities and fingers. There exist five types of Hanhart syndrome, with the severity and nature of the condition ranging widely on a case-by-case basis. Hanhart syndrome is classified as a rare disease, with approximately 30 known cases having been reported between 1932 and 1991. Early hypotheses believed that the disorder was caused by genetic conditions, with a more recent hypothesis demonstrating that the disorder may be caused by hemorrhagic lesions during prenatal development. The causal mechanism behind this vascular disruption is still unknown.
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