Profound impairment of galactose-1-phosphate uridylyltransferase (GALT) results in the inborn error of metabolism known as classic galactosemia. Although the acute and potentially lethal sequelae of this disorder can be resolved or prevented by early detection and lifelong dietary restriction of galactose, many treated patients nevertheless go on to experience serious long-term complications, including cognitive disabilities and speech/language disorders in nearly half of all patients, and primary or premature ovarian failure in close to 85% of female patients. Despite more than 50 years of investigation, the mechanisms underlying the pathophysiology of galactosemia remain unclear, and animal models of the disease have failed to recapitulate the patient phenotype, further complicating studies. The long-term goal of our proposed research is to define the biochemical bases of this pathophysiology, thereby enabling development of novel and more effective treatments for patients with galactosemia. Our short-term objective is to define the roles of specific biochemical factors, including aberrant glycosylation, as potential mediators of galactose sensitivity in GALT- and/or GALE-impaired yeast and mammalian cells. We further propose to test the roles of these same candidate factors as potential mediators of outcome in a large cohort of patients with classic galactosemia.
Our Specific Aims are: (1) to define the roles of GALK, GALE, and UGP1 as candidate modifiers of galactose sensitivity in yeast and human cell model systems of galactosemia, (2) to define the nature and underlying cause(s) of aberrant glycosylation in fibroblasts from patients with classic galactosemia and generalized epimerase-deficiency galactosemia, and (3) to define biochemical modifiers of patient outcomes in a cohort of classic galactosemia patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK059904-10
Application #
8094274
Study Section
Special Emphasis Panel (ZRG1-GGG-B (02))
Program Officer
Mckeon, Catherine T
Project Start
2001-08-01
Project End
2013-06-30
Budget Start
2011-07-01
Budget End
2013-06-30
Support Year
10
Fiscal Year
2011
Total Cost
$373,784
Indirect Cost
Name
Emory University
Department
Genetics
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Shaw, Kelly A; Mulle, Jennifer G; Epstein, Michael P et al. (2017) Gastrointestinal Health in Classic Galactosemia. JIMD Rep 33:27-32
Liu, Ying; Sidhu, Alpa; Bean, Lora H et al. (2015) Genetic and functional studies reveal a novel noncoding variant in GALT associated with a false positive newborn screening result for galactosemia. Clin Chim Acta 446:171-4
Li, Yijun; Huang, Xiaoping; Harmonay, Lauren et al. (2014) Liquid chromatography-tandem mass spectrometry enzyme assay for UDP-galactose 4'-epimerase: use of fragment intensity ratio in differentiation of structural isomers. Clin Chem 60:783-90
Spencer, Jessica B; Badik, Jennifer R; Ryan, Emily L et al. (2013) Modifiers of ovarian function in girls and women with classic galactosemia. J Clin Endocrinol Metab 98:E1257-65
McCorvie, Thomas J; Gleason, Tyler J; Fridovich-Keil, Judith L et al. (2013) Misfolding of galactose 1-phosphate uridylyltransferase can result in type I galactosemia. Biochim Biophys Acta 1832:1279-93
Ryan, Emily L; Lynch, Mary Ellen; Taddeo, Elles et al. (2013) Cryptic residual GALT activity is a potential modifier of scholastic outcome in school age children with classic galactosemia. J Inherit Metab Dis 36:1049-61
Liu, Ying; Xia, Baoyun; Gleason, Tyler J et al. (2012) N- and O-linked glycosylation of total plasma glycoproteins in galactosemia. Mol Genet Metab 106:442-54
McCorvie, Thomas J; Liu, Ying; Frazer, Andrew et al. (2012) Altered cofactor binding affects stability and activity of human UDP-galactose 4'-epimerase: implications for type III galactosemia. Biochim Biophys Acta 1822:1516-26
Jumbo-Lucioni, Patricia P; Garber, Kathryn; Kiel, John et al. (2012) Diversity of approaches to classic galactosemia around the world: a comparison of diagnosis, intervention, and outcomes. J Inherit Metab Dis 35:1037-49
Badik, Jennifer R; Castaneda, Uriel; Gleason, Tyler J et al. (2011) Ovarian function in Duarte galactosemia. Fertil Steril 96:469-473.e1

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