RASopathies are pathologies linked to genes in the RAS/MAPK pathway, including the gene encoding the PTPN11 protein (involved in half of Noonan syndromes). An international consortium of researchers has reported the observations of four children:
- all had mutations in the PTPN11 gene but had previously been investigated for suspected congenital myasthenic syndrome (CMS),
- the clinical picture was one of muscular fatigue exacerbated by exercise, a muscle deficit of variable intensity and a positive response to treatment with anticholesterase agents or salbutamol (in half the cases),
- the proteomic profile was also consistent with SMC.
Facial dysmorphia and intellectual deficiency should always raise the possibility of Noonan syndrome or LEOPARD syndrome in cases of suspected MSC that have not been molecularly confirmed.
