Positions

Professor
Neurology, Neuroscience, and Molecular & Human Genetics
Baylor College of Medicine
Director
Blue Bird Circle Developmental Neurogenetics Laboratory
Baylor College of Medicine
Graduate Program Faculty
Integrative Molecular and Biomedical Sciences;
Translational Biology and Molecular Medicine
Baylor College of Medicine
Professor
Program in Translational Biology & Molecular Medicine
Baylor College of Medicine
Endowed Chair in Neurogenetics
Cullen Trust for Health Care

Education

Post-Doctoral Fellowship at Harvard University
Residency at Massachusetts General Hospital
PhD from Stanford University
MD from Yale University School Of Medicine
BA from Reed College

Certifications

Neurology
American Board of Psychiatry and Neurology

Professional Interests

  • Gene control of neuronal excitability within the developing mammalian CNS
  • Inherited neurological diseases
  • Epilepsy

Professional Statement

The principal research strategy in the Developmental Neurogenetics Laboratory is to apply mutational analysis to learn how genes regulate neuronal excitability and network synchronization within the mammalian central nervous system. Spontaneous and transgenic mutations that express neurological phenotypes in the mouse provide a valuable opportunity to identify excitability genes and examine their role in synaptic plasticity in the developing brain.

Brain wave (EEG) phenotypes emerge from altered neuronal signaling properties, and are of special interest. Six mouse mutants causing spike-wave synchronization of the neocortex have been discovered in our laboratory (tottering, lethargic, ducky, and stargazer, slow wave, and mocha) and are linked to mutations of voltage-gated calcium ion channels, AMPA receptor trafficking TARP subunits, a sodium hydrogen exchanger, and vesicular zinc trafficking. Study of these mice have led to the identification of novel members of the TARP gene family, and a new understanding of how related molecules rescue function and determine selective vulnerability within thalamocortical pathways. Other new mouse models for human epilepsy syndromes involving mutant ion channel, receptor, synaptic vesicle proteins, and transcription factors for interneuron migration are being analyzed to pinpoint the neural network and specific electrophysiological abnormalities characteristic of the human disorder. We are also exploring activity-induced changes of downstream gene expression and conditional gene silencing in epileptic brain to identify regulatory pathways that are critical mechanisms of disease progression. Some of these genes, such as those for glutamate and GABA transporters and apoptotic pathways suggest distinct mechanisms for seizure-induced excitotoxicity and cell death.

Our laboratory recently discovered that mouse models of Alzheimer’s Disease show non-convulsive cortical hyperexcitability, heralding a paradigm change in understanding the basis for cognitive disorders in familial AD. We have also identified MAPT1, the gene for tau protein, as a critical modifier of AD-linked cognitive decline and epilepsy.

At present, mutant mouse models of inherited disorders in neuronal excitability are under investigation using the molecular anatomical techniques of in situ hybridization and immunohistochemistry, quantitative analysis of seizure-activated mRNAs, in vivo and in vitro cell physiology, and optical fluorescence measurements of ion channel activity in presynaptic terminals of mouse brain slices. These studies form the basis for development of strategies to selectively correct the tissue expression of neuronal gene errors early in development.

In collaboration with the Baylor Human Genome Sequencing Center and a $4.5 million NIH grant, our laboratory performed a large-scale translational genomic research study examining variants in human ion channel genes. The Human Channelopathy Project revealed extensive complexity of disease-linked genes, and we are currently evaluating the contribution of SNP patterns as well as copy number variation in several hundred ion channel subunit genes to the complex inheritance of neurological excitability disorders such as epilepsy. A second and related large collaborative NIH funded Center project focusing on risk prediction of variants in ion channel genes linked to neurocardiac phenotypes is underway.

Selected Publications