How did you become interested in the genetics of glaucoma?
I have always been interested in disease mechanisms and
especially the molecular events that are responsible for disease.
Because therapy usually involves a
molecular interaction, understanding a
condition on a molecular level makes it
possible to think about actually curing a
disease. Genetics is one way that the
molecular events responsible for a disease
can be identified. For glaucoma, a
genetic approach makes it possible to
define the molecular pathophysiology of
the disease without directly accessing
diseased tissue, which can be very difficult
in glaucoma patients.
When will we be able to define glaucoma by genotypes, and how will that influence clinical care and therapy?
In some cases, we can already define glaucoma by genotypes,
but currently those cases are rare and are limited to
early-onset forms of the disease with mendelian inheritance.
The identification of risk factors for the more common
complex types of glaucoma (primary open-angle,
exfoliation, and low-tension) is the anticipated result of the
genome-wide association studies that my colleagues and I
are currently conducting. Identifying these genetic risk factors
will make it possible to screen patient populations for
individuals who are at higher risk of developing glaucoma,
thus allowing the initiation of treatment at earlier stages of
the disease when it may be more effective.
We also expect that the genetic risk factors
discovered through our genome association
studies will identify molecular
abnormalities that contribute to the disease
process. Finally, we anticipate that the
modification of these abnormal molecular
events could lead to novel therapeutic
approaches that are directed toward the
actual cause of the disease and that may
be more effective than current pressure-lowering
medications.
What are the challenges of conducting a genomewide
study, and what is the potential impact of your
upcoming genome-wide association study for primary
open-angle glaucoma, funded by the National
Human Genome Research Institute and the National
Eye Institute?
Genome-wide association studies have three main components:
the patient sample collection (both DNA and phenotypic information); the molecular testing, in this case, whole
genome genotyping of over 600,000 single-nucleotide polymorphisms
for each sample; and analysis of all the data. Each step
requires specialized expertise. For a complex disease such as glaucoma,
the overall size of the study needs to be large enough that it
has sufficient statistical power to identify multiple genetic factors
of variable effect.
The NEIGHBOR (NEI Glaucoma Human Genetics Collaboration) Consortium has 22 investigators, involves eight institutions, and has enrolled more than 4,000 participants with DNA and phenotypic information. In addition, this study is being carried out in collaboration with the GENEVA (GLAUGEN; Louis Pasquale MD, primary investigator) Glaucoma Genome Wide Association Study funded by the National Human Genome Research Institute that includes another 2,400 participants. These two studies will produce billions of genotypes for analysis. Organizing and coordinating this project is challenging and has required grant writing, inperson meetings, conference calls, and many, many emails. Fortunately, we have a tremendous team of expert investigators involved in this work.
Your clinical practice includes patients with inherited ocular disorders.
What teaching points for medical students, residents,
and fellows do you draw from this patient population, and how
are they similar to and/or different from those derived from
your treatment of patients with glaucoma?
In my opinion, the most important part of clinical care is educating
patients. In that regard, individuals with inherited ocular disorders do not differ from glaucoma patients. For patients with
inherited eye disease, however, usually the whole family is in the
examining room, and the discussion includes counseling about the
risk of disease for all family members. For some of these cases, I can take a patient sample back to the laboratory to test for mutations in a specific gene. If a mutation is found, I can give definitive information to family members about their status as mutation carriers. One of the most gratifying patient/doctor discussions is when I get to tell someone that he or she does not have the mutation and that his or her children will not inherit the disease.
Aside from the academic environment, what do you enjoy about living in Boston?
Having spent the first 2 decades of my life on the West Coast,
coming to Boston for medical school was an experiment that I
expected to last only 4 years. I thought the winters alone would
drive me back to Seattle or Berkeley, California, where I went to
college. As it turns out, one of the things I like most about Boston
is the weather. The change in seasons is refreshing, and unlike
Seattle, it is never cloudy for more than a few days at a time, even
in the winter. I am also a sports addict, and Boston is a great town
for running, biking, skiing, and of course, watching the Red Sox at
Fenway Park!
