Breathing abnormalities in a female mouse model of Rett syndrome

Rett syndrome (RTT) is a female neurodevelopmental disease with breathing abnormalities. To understand whether breathing defects occur in the early lives of a group of female Mecp2 (+/-) mice, a mouse model of RTT, and what percentage of mice shows RTT-like breathing abnormality, breathing activity was measured by plethysmography in conscious mice. Breathing frequency variation and central apnea in a group of Mecp2 (+/-) females displayed a distribution pattern similar to Mecp2 (-/Y) males, while the rest resembled the wild-type mice. Similar results were obtained using the k-mean clustering statistics analysis. With two independent methods, about 20 % of female Mecp2 (+/-) mice showed RTT-like breathing abnormalities that began as early as 3 weeks of age in the Mecp2 (+/-) mice, and were suppressed with 3 % CO2. The finding that only a small proportion of Mecp2 (+/-) mice develops RTT-like breathing abnormalities suggests incomplete allele inactivation in the RTT-model Mecp2 (+/-) mice.