Biallelic variants in COX4I1 associated with a novel phenotype resembling Leigh syndrome with developmental regression, intellectual disability, and seizures
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
Authors: Pillai, Nishitha R.; AlDhaheri, Noura S.; Ghosh, Rajarshi; Lim, Jaehyung; Streff, Haley; Nayak, Anuranjita; Graham, Brett H.; Hanchard, Neil A.; Elsea, Sarah H.; Scaglia, Fernando
Abstract
Autosomal recessive COX4I1 deficiency has been previously reported in a single individual with a homozygous pathogenic variant in COX4I1, who presented with short stature, poor weight gain, dysmorphic features, and features of Fanconi anemia. COX4I1 encodes subunit 4, isoform 1 of cytochrome c oxidase. Cytochrome c oxidase is a respiratory chain enzyme that plays an important role in mitochondrial electron transport and reduces molecular oxygen to water leading to the formation of ATP. Defective production of cytochrome c oxidase leads to a variable phenotypic spectrum ranging from isolated myopathy to Leigh syndrome. Here, we describe two siblings, born to consanguineous parents, who presented with encephalopathy, developmental regression, hypotonia, pathognomonic brain imaging findings resembling Leigh-syndrome, and a novel homozygous variant on COX4I1, expanding the known clinical phenotype associated with pathogenic variants in COX4I1.
Alterations in oxidative gene expression in equine skeletal muscle following exercise and training
PHYSIOLOGICAL GENOMICS
Authors: Eivers, Suzanne S.; McGivney, Beatrice A.; Fonseca, Rita G.; MacHugh, David E.; Menson, Katie; Park, Stephen D.; Rivero, Jose-Luis L.; Taylor, Cormac T.; Katz, Lisa M.; Hill, Emmeline W.
Abstract
Eivers SS, McGivney BA, Fonseca RG, MacHugh DE, Menson K, Park SD, Rivero JL, Taylor CT, Katz LM, Hill EW. Alterations in oxidative gene expression in equine skeletal muscle following exercise and training. Physiol Genomics 40: 83-93, 2010. First published October 27, 2009; doi: 10.1152/physiolgenomics.00041.2009.-Intense selection for elite racing performance in the Thoroughbred horse (Equus caballus) has resulted in a number of adaptive physiological phenotypes relevant to exercise; however, the underlying molecular mechanisms responsible for these characteristics are not well understood. Adaptive changes in mRNA expression in equine skeletal muscle were investigated by real-time qRT-PCR for a panel of candidate exercise-response genes following a standardized incremental-step treadmill exercise test in eight untrained Thoroughbred horses. Biopsy samples were obtained from the gluteus medius before, immediately after, and 4 h after exercise. Significant (P < 0.05) differences in gene expression were detected for six genes (CKM, COX4I1, COX4I2, PDK4, PPARGC1A, and SLC2A4) 4 h after exercise. Investigation of relationships between mRNA and velocity at maximum heart rate (VHRmax) and peak postexercise plasma lactate concentration ([La]T-1) revealed significant (P < 0.05) associations with postexercise COX4I1 and PPARCG1A expression and between [La]T-1 and basal COX4I1 expression. Gene expression changes were investigated in a second cohort of horses after a 10 mo period of training. In resting samples, COX4I1 gene expression had significantly increased following training, and, after exercise, significant differences were identified for COX4I2, PDK4, and PPARGC1A. Significant relationships with VHRmax and [La]T-1 were detected for PPARGC1A and COX4I1. These data highlight the roles of genes responsible for the regulation of oxygen-dependent metabolism, glucose metabolism, and fatty acid utilization in equine skeletal muscle adaptation to exercise.