Scientists have found increases in the numbers of neurons in brain regions of autistic children, suggesting a problem in developmental programmed cell death pathways. One of the most important effectors of neuronal survival during brain development is the “anti-cell death” protein Bcl-xL. While the normal function of Bcl-xL is to maintain a healthy number of neurons and synapses, over-expressed Bcl-xL can cause an overabundance of synaptic connections. This may be happening in Fragile X.

In the process of this study, Dr. Jonas discovered a more fundamental abnormality: the cells’ mitochondria — which produce energy — have a leaky inner membrane. When a leak in the cell’s mitochondria short-circuits efficient functioning of the synapse, memory, learning and typical brain development are all compromised, Jonas said.