Legius syndrome
Legius syndrome (LS) is an autosomal dominant condition characterized by cafe au lait spots. It was first described in 2007 and is often mistaken for Neurofibromatosis type I (NF-1). It is caused by mutations in the SPRED1 gene. It is also known as Neurofibromatosis Type 1-like syndrome (NFLS). The syndrome is named after Eric Legius, Professor at the KU Leuven. It is a RASopathy.
Symptoms
Nearly all patients show multiple Café au lait spots. Other symptoms may include:
Features common in neurofibromatosis - Lisch nodules, bone abnormalities, neurofibromas, optic pathway gliomas and malignant peripheral nerve sheath tumors - are absent in this condition.
Diagnosis
Genetic testing is necessary to identify the syndrome. The test checks for loss of function mutations in the SPRED1 gene.
Confusion with Neurofibromatosis Type I
The symptoms of Legius syndrome and NF-1 are very similar. This is the reason why the two are easily confused. A genetic test is often the only way to make sure a person has LS and not NF-1. The similarity of symptoms stem from the fact that the different genes affected in the two syndromes code for proteins that carry out a similar task in the same reaction pathway.
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