Comparison of an expanded ataxia interactome with patient medical records reveals a relationship between macular degeneration and ataxia

• Published in: Human molecular genetics 2011-02, Vol.20 (3), p.510-527
• Main Authors: KAHLE, Juliette J, GULBAHCE, Natali, SHAW, Chad A, LIM, Janghoo, HILL, David E, BARABASI, Albert-László, ZOGHBI, Huda Y
• Format: Article
• Language: English
• Subjects: Animals; Ataxin-7; Biological and medical sciences; Calcium Channels - genetics; Calcium Channels - metabolism; Comorbidity; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Knock-In Techniques; Genetics of eukaryotes. Biological and molecular evolution; Humans; In Situ Hybridization; Macular Degeneration - genetics; Macular Degeneration - metabolism; Medical Records; Medical sciences; Medicare; Mice; Molecular and cellular biology; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; Retina - abnormalities; Retina - metabolism; Spinocerebellar Ataxias - genetics; Spinocerebellar Ataxias - metabolism; Trinucleotide Repeat Expansion; United States
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/ddq496

Spinocerebellar ataxias 6 and 7 (SCA6 and SCA7) are neurodegenerative disorders caused by expansion of CAG repeats encoding polyglutamine (polyQ) tracts in CACNA1A, the alpha1A subunit of the P/Q-type calcium channel, and ataxin-7 (ATXN7), a component of a chromatin-remodeling complex, respectively. We hypothesized that finding new protein partners for ATXN7 and CACNA1A would provide insight into the biology of their respective diseases and their relationship to other ataxia-causing proteins. We identified 118 protein interactions for CACNA1A and ATXN7 linking them to other ataxia-causing proteins and the ataxia network. To begin to understand the biological relevance of these protein interactions within the ataxia network, we used OMIM to identify diseases associated with the expanded ataxia network. We then used Medicare patient records to determine if any of these diseases co-occur with hereditary ataxia. We found that patients with ataxia are at 3.03-fold greater risk of these diseases than Medicare patients overall. One of the diseases comorbid with ataxia is macular degeneration (MD). The ataxia network is significantly (P= 7.37 × 10(-5)) enriched for proteins that interact with known MD-causing proteins, forming a MD subnetwork. We found that at least two of the proteins in the MD subnetwork have altered expression in the retina of Ataxin-7(266Q/+) mice suggesting an in vivo functional relationship with ATXN7. Together these data reveal novel protein interactions and suggest potential pathways that can contribute to the pathophysiology of ataxia, MD, and diseases comorbid with ataxia.