Genetics of mitochondrial respiratory chain deficiencies

Area of Science:

• Biochemistry
• Genetics
• Cellular Respiration

Background:

• Oxidative phosphorylation (ATP synthesis via the respiratory chain) is vital for energy supply and functions from birth.
• Its dual genetic origin (nuclear and mitochondrial DNA) theoretically allows symptoms in any organ, at any age, with any inheritance pattern.
• Historically, mitochondrial DNA mutations were solely implicated in RC disorders, a view now evolving.

Purpose of the Study:

• To highlight the expanding role of nuclear gene mutations in respiratory chain disorders.
• To underscore the complexity of RC disorders due to their genetic origins.
• To correct the misconception that only mitochondrial DNA mutations cause these conditions.

Main Methods:

• Review of genetic databases and literature on respiratory chain disorders.
• Analysis of reported cases linking nuclear gene mutations to RC dysfunction.
• Comparative analysis of nuclear and mitochondrial DNA contributions to RC assembly and function.

Main Results:

• A growing number of disease-causing mutations are identified in nuclear genes affecting RC components.
• Nuclear genes encode not only subunits but also proteins crucial for holoenzyme biogenesis and mtDNA metabolism.
• This expands the known genetic basis of respiratory chain deficiencies.

Conclusions:

• Respiratory chain disorders result from mutations in both nuclear and mitochondrial DNA.
• The understanding of RC disorder etiology is broadening to include a significant contribution from nuclear genes.
• Accurate diagnosis requires consideration of both genetic origins.