Paediatrics (RCH) - Research Publications

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    Mitochondrial DNA Variation and Disease Susceptibility in Primary Open-Angle Glaucoma
    Singh, LN ; Crowston, JG ; Sanchez, MIGL ; Van Bergen, NJ ; Kearns, LS ; Hewitt, AW ; Yazar, S ; Mackey, DA ; Wallace, DC ; Trounce, IA (ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2018-09)
    PURPOSE: To determine whether mitochondrial DNA haplogroups or rare variants associate with primary open-angle glaucoma in subjects of European descent. METHODS: A case-control comparison of age- and sex-matched cohorts of 90 primary open-angle glaucoma patients and 95 population controls. Full mitochondrial DNA sequences from peripheral blood were generated by next-generation sequencing and compared to the revised Cambridge Reference Sequence to define mitochondrial haplogroups and variants. RESULTS: Most subjects were of the major European haplogroups H, J, K, U, and T. Logistic regression analysis showed haplogroup U to be significantly underrepresented in male primary open-angle glaucoma subjects (odds ratio 0.25; 95% confidence interval [CI] 0.09-0.67; P = 0.007; Bonferroni multiple testing P = 0.022). Variants in the mitochondrial DNA gene MT-ND2 were overrepresented in the control group (P = 0.005; Bonferroni multiple testing correction P = 0.015). CONCLUSIONS: Mitochondrial DNA ancestral lineages modulate the risk for primary open-angle glaucoma in populations of European descent. Haplogroup U and rare variants in the mitochondrial DNA-encoded MT-ND2 gene may be protective against primary open-angle glaucoma. Larger studies are warranted to explore haplogroup associations with disease risk in different ethnic groups and define biomarkers of primary open-angle glaucoma endophenotypes to target therapeutic strategies.
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    Mitochondrial replacement in an iPSC model of Leber's hereditary optic neuropathy
    Wong, RCB ; Lim, SY ; Hung, SSC ; Jackson, S ; Khan, S ; Van Bergen, NJ ; De Smit, E ; Liang, HH ; Kearns, LS ; Clarke, L ; Mackey, DA ; Hewitt, AW ; Trounce, IA ; Pebay, A (IMPACT JOURNALS LLC, 2017-04)
    Cybrid technology was used to replace Leber hereditary optic neuropathy (LHON) causing mitochondrial DNA (mtDNA) mutations from patient-specific fibroblasts with wildtype mtDNA, and mutation-free induced pluripotent stem cells (iPSCs) were generated subsequently. Retinal ganglion cell (RGC) differentiation demonstrates increased cell death in LHON-RGCs and can be rescued in cybrid corrected RGCs.
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    Friedreich's ataxia induced pluripotent stem cell-derived cardiomyocytes display electrophysiological abnormalities and calcium handling deficiency
    Crombie, DE ; Curl, CL ; Raaijmakers, AJA ; Sivakumaran, P ; Kulkarni, T ; Wong, RCB ; Minami, I ; Evans-Galea, MV ; Lim, SY ; Delbridge, L ; Corben, LA ; Dottori, M ; Nakatsuji, N ; Trounce, IA ; Hewitt, AW ; Delatycki, MB ; Pera, MF ; Pebay, A (IMPACT JOURNALS LLC, 2017-05)
    We sought to identify the impacts of Friedreich's ataxia (FRDA) on cardiomyocytes. FRDA is an autosomal recessive degenerative condition with neuronal and non-neuronal manifestations, the latter including progressive cardiomyopathy of the left ventricle, the leading cause of death in FRDA. Little is known about the cellular pathogenesis of FRDA in cardiomyocytes. Induced pluripotent stem cells (iPSCs) were derived from three FRDA individuals with characterized GAA repeats. The cells were differentiated into cardiomyocytes to assess phenotypes. FRDA iPSC- cardiomyocytes retained low levels of FRATAXIN (FXN) mRNA and protein. Electrophysiology revealed an increased variation of FRDA- cardiomyocyte beating rates which was prevented by addition of nifedipine, suggestive of a calcium handling deficiency. Finally, calcium imaging was performed and we identified small amplitude, diastolic and systolic calcium transients confirming a deficiency in calcium handling. We defined a robust FRDA cardiac-specific electrophysiological profile in patient-derived iPSCs which could be used for high throughput compound screening. This cell-specific signature will contribute to the identification and screening of novel treatments for this life-threatening disease.