A novel in-frame 18-bp microdeletion in MT-CYB causes a multisystem disorder with prominent exercise intolerance.

Abstract

A novel heteroplasmic mitochondrial DNA (mtDNA) microdeletion affecting the cytochrome b gene (MT-CYB) was identified in an Italian female patient with a multisystem disease characterized by sensorineural deafness, cataracts, retinal pigmentary dystrophy, dysphagia, postural and gait instability, and myopathy with prominent exercise intolerance. The deletion is 18-base pair long and encompasses nucleotide positions 15,649-15,666, causing the loss of six amino acids (Ile-Leu-Ala-Met-Ile-Pro) in the protein, but leaving the remaining of the MT-CYB sequence in frame. The defective complex III function was cotransferred with mutant mtDNA in cybrids, thus unequivocally establishing its pathogenic role. Maternal relatives failed to show detectable levels of the deletion in blood and urinary epithelium, suggesting a de novo mutational event. This is the second report of an in-frame intragenic deletion in MT-CYB, which most likely occurred in early stages of embryonic development, associated with a severe multisystem disorder with prominent exercise intolerance.

• Authors: Valeria Carossa, Anna Ghelli, Concetta Valentina Tropeano, Maria Lucia Valentino, Luisa Iommarini, Alessandra Maresca, Leonardo Caporali, Chiara La Morgia, Rocco Liguori, Piero Barboni, Michele Carbonelli, Giovanni Rizzo, Caterina Tonon, Raffaele Lodi, Andrea Martinuzzi, Vera De Nardo, Michela Rugolo, Luca Ferretti, Francesca Gandini, Maria Pala, Alessandro Achilli, Anna Olivieri, Antonio Torroni, Valerio Carelli
• Journal: Human mutation (Hum Mutat) Vol. 35 Issue 8 Pg. 954-8 (Aug 2014) ISSN: 1098-1004 [Electronic] United States
• PMID: 24863938 (Publication Type: Case Reports, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 WILEY PERIODICALS, INC.

Chemical References

• DNA, Mitochondrial
• Cytochromes b

Topics

• Adult
• Base Sequence
• Cataract (genetics, pathology)
• Cytochromes b (genetics)
• DNA, Mitochondrial (genetics)
• Deglutition Disorders (genetics, pathology)
• Fatigue (genetics, pathology)
• Female
• Gene Expression
• Hearing Loss, Sensorineural (genetics, pathology)
• Humans
• Molecular Sequence Data
• Muscular Diseases (genetics, pathology)
• Pigment Epithelium of Eye (pathology)
• Sequence Deletion
• Tooth Discoloration (genetics, pathology)