Related Experiment Video
Updated: Jul 7, 2026
A Non-random Mouse Model for Pharmacological Reactivation of Mecp2 on the Inactive X Chromosome
Published on: May 22, 2019
Comparative study of brain morphology in Mecp2 mutant mouse models of Rett syndrome
Nadia P Belichenko1, Pavel V Belichenko, Hong Hua Li
1Department of Genetics, Stanford University, Stanford, California 94305-5489, USA.
Abstract:
Rett syndrome (RTT) is caused by mutations in the X-linked gene MECP2. While patients with RTT show widespread changes in brain function, relatively few studies document changes in brain structure and none examine in detail whether mutations causing more severe clinical phenotypes are linked to more marked changes in brain structure. To study the influence of MeCP2-deficiency on the morphology of brain areas and axonal bundles, we carried out an extensive morphometric study of two Mecp2-mutant mouse models (Mecp2B and Mecp2J) of RTT. Compared to wildtype littermates, striking changes included reduced brain weight ( approximately 13% and approximately 9%) and the volumes of cortex ( approximately 11% and approximately 7%), hippocampus (both by approximately 8%), and cerebellum ( approximately 12% and 8%) in both mutant mice. At 3 weeks of age, most (24 of 47) morphological parameters were significantly altered in Mecp2B mice; fewer (18) were abnormal in Mecp2J mice. In Mecp2B mice, significantly lower values for cortical area were distributed along the rostrocaudal axis, and there was a reduced length of the olfactory bulb ( approximately 10%) and periaqueductal gray matter ( approximately 16%). In Mecp2J mice, while there was significant reduction in rostrocaudal length of cortex, this parameter was also abnormal in hippocampus ( approximately 10%), periaqueductal gray matter ( approximately 13%), fimbria ( approximately 18%), and anterior commissure ( approximately 10%). Our findings define patterns of Mecp2 mutation-induced changes in brain structure that are widespread and show that while some changes are present in both mutants, others are not. These observations provide the underpinning for studies to further define microarchitectural and physiological consequences of MECP2 deficiency.
Insights
Rett syndrome (RTT) brain structure is significantly altered by MECP2 gene mutations. This study reveals widespread changes in brain areas and axonal bundles in mouse models, correlating MeCP2 deficiency with specific morphological deficits.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the MECP2 gene.
- While functional brain changes in RTT are known, structural alterations and their correlation with disease severity remain underexplored.
Purpose of the Study:
- To investigate the impact of MeCP2 deficiency on brain morphology in RTT mouse models.
- To determine if different MECP2 mutations lead to varying degrees of structural brain changes.
Main Methods:
- Morphometric analysis of two Mecp2-mutant mouse models (Mecp2B and Mecp2J) compared to wildtype littermates.
- Detailed examination of brain weight, regional volumes, and specific axonal bundle dimensions.
Main Results:
- Both Mecp2B and Mecp2J mice exhibited reduced brain weight, cortex, hippocampus, and cerebellum volumes.
- Mecp2B mice showed more widespread morphological alterations (24/47 parameters) than Mecp2J mice (18/47 parameters) at 3 weeks.
- Specific reductions were observed in cortical area, olfactory bulb, periaqueductal gray matter, hippocampus, fimbria, and anterior commissure, varying between mutant models.
Conclusions:
- MECP2 deficiency induces widespread and distinct patterns of brain structural changes.
- The severity of morphological alterations in the brain correlates with the specific Mecp2 mutation.
- These findings provide a foundation for understanding the microarchitectural and physiological consequences of MECP2 deficiency in RTT.
