Methionyl-tRNA synthetase (MARS) catalyzes the ligation of methionine to tRNA and is critical for protein biosynthesis. We identified biallelic missense mutations in MARS in a specific form of pediatric pulmonary alveolar proteinosis (PAP), a severe lung disorder that is prevalent on the island of Réunion and the molecular basis of which is unresolved. Mutations were found in 26 individuals from Réunion and nearby islands and in two families from other countries. Functional consequences of the mutated alleles were assessed by growth of wild-type and mutant strains and methionine-incorporation assays in yeast. Enzyme activity was attenuated in a liquid medium without methionine but could be restored by methionine supplementation. In summary, identification of a founder mutation in MARS led to the molecular definition of a specific type of PAP and will enable carrier screening in the affected community and possibly open new treatment opportunities.

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For years, vitamin D has been associated to many immune disorders. Several studies have shown association between low serum 25 OH vitamin D and type 1 diabetes mellitus (T1DM).Objective: To compare 25 hydroxy vitamin D (25 OHD) level in T1DM patients to non-diabetic children hospitalized or seen in emergency for other diseases at the same period.Methods: It was a case-control study including 29 patients with T1DM and 28 non -diabetic control children. They were comparable in age, gender, weight, length, BMI and season of blood sampling. Epidemiological and clinical data were collected and 25OHD serum level was measured with a radioimmunoassay kit.Results: 25OHD level was significantly lower in diabetic patients (mean: 19.62 ng/ml, range 15-26 ng/ml) than in control patients (24.64 ng/ml, 20-28 ng/ml), p=0.00. All participants (T1DM patients and controls) had inadequate levels of vitamin D. Conclusion:Children with T1DM have lower vitamin D levels than control group.

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