BCS1L mutations cause disease phenotypes ranging from highly restricted pili torti and sensorineural hearing loss (the Björnstad syndrome) to profound multisystem organ failure (complex III deficiency and the GRACILE syndrome). All BCS1L mutations disrupted the assembly of mitochondrial respirasomes (the basic unit for respiration in human mitochondria), but the clinical expression of the mutations was correlated with the production of reactive oxygen species. Mutations that cause the Björnstad syndrome illustrate the exquisite sensitivity of ear and hair tissues to mitochondrial function, particularly to the production of reactive oxygen species.

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The results suggest that while both methods may be useful, they describe related but not identical aspects of skin mechanics. The differences in measuring principle suggest that the suction cup method predominantly measures elasticity, while the ballistometer predominantly appears to measure stiffness. Hysteresis may be a unique measure of skin viscosity. Additional studies, however, are needed to specify the clinical significance of the various measures of skin mechanics.