Identification of the genetic causes of orphan diseases
Esteves, Kristyn M.
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Background: Orphan diseases are defined as any disease, syndrome, or disorder that affects less than 200,000 persons in the United States. Most of these disorders are genetic in origin. However, with so few patients to study, researchers have struggled to collect enough data on any one orphan disease to make progress towards treatment and/or a cure. But, with the recent monumental advances in the field of genetic sequencing techniques, there has been an explosion in the potential avenues of study for these scientists. We hope to use data generated from whole exome studies of our orphan disease patients to identify potential disease-causing genetic lesions, and therefore solve the mystery of the genetic basis of their condition. Methods: For each family enrolled in our study, genomic DNA samples from the proband and his/her mother and father were evaluated for whole exome sequencing (performed by Axeq Technologies). We sorted and filtered these results using a variety of parameters until discovering a genetic variant we believed to potentially explain the phenotype of each patient. Once a gene of interest was identified, we used Sanger sequencing to confirm the mutation. At the present moment, we are at a variety of stages of progress amongst our study of our different patients. For our patients thought to be affected by dysfunctional SPEG, we have been working on a SPEG-CKO mouse model in attempt to recreate the phenotype we see in our patients and further study the function of SPEG. For our patient thought to be affected by dysfunctional PHKG1 and our patient thought to be affected by dysfunctional LAMA1, we are in the process of studying whether their mutations affect the expression and/or function of the associated proteins. Results: While we are still developing our mouse colonies, we have successfully developed a SPEG-CKO mouse model. With respect to PHKG1, we are still searching for another mutation, for both the proband and father are heterozygous for the same frameshift mutation, but only the proband is clinically affected. Our studies of LAMA1 appear promising, for the patient carries two mutations which segregate to each parent. However, more data must be collected on the expression of this protein, particularly with respect to whether it could cause the pontocerebellar hypoplasia phenotype. Conclusion: While major challenges still remain for orphan disease research, we will continue our investigations in hopes of determining the genetic basis of disease in these marginalized patients.
Thesis (M.A.)--Boston University