MECP2 and metabolic syndrome: While this may be the case for some models at relatively early time points, a recent study of female heterozygous MeCP2 mutants showed that those that had some C57BL6 background but no 129 background were overweight at one year of age; it is not known at what point they became overweight, or if there would have been other indications of metabolic syndrome prior to the one-year time point[49].