Administration of Methionine in Patients With Pulmonary Alveolar Proteinosis by Mutation of the MARS Gene.

Inclusion Criteria: * Minor Patient with alveolar proteinosis by double mutation Ala393Thr and SER567LEU of the MARS gene, genetically proven. * Patient in need of prolonged hospitalization in Necker for treatment of bronchial-alveolar washes in the context of care. * Patient for which methionine can be administered orally or by enteral probe (Nasogastric or gastrostomy probe) * Signed Informed consent form by parents / legal guardian Exclusion Criteria: * Patient with alveolar proteinosis by other mutations of the MARS gene * Patient with alveolar proteinosis secondary to another etiology or without identified cause * Refusal to participate in the study * High blood pressure requiring drug treatment * Heart failure * Known hypersensitivity to one of the substances used or potentially used in the study: methionine, vitamins B6, B12, B9 and C * Pre-Hypermethioninemia (Methioninemia \> + 2 DS of normal for age) whatever the cause