Mitochondrial genes are critical to the energy metabolism of cells, but mitochondrial disorders caused by mutations in these genes are generally not lethal. Why not?

Mitochondria are the organelle present within the cells. The mitochondrial genome has more than 37 genes present in it. These are the genes that code for the protein responsible for mitochondrial functions, such as cellular respiration.

The defect that affects the normal functioning of mitochondria is known as a mitochondrial disorder. The mutation in the mitochondrial genes results in mitochondrial disease.

The person having mitochondrial disorder will have normal as well as mutant mitochondria. The mitochondria are the abundant organelles found in the cell.

The mutations that happen in the mitochondrial genes lead to a mitochondrial disorder.

The affected person possesses normal mitochondria and mutant mitochondria. The presence of normal mitochondria performs cellular respiration for the survival of the organism.

Hence, the mutation in the necessary mitochondrial genes is not lethal in the case of mitochondrial disorders.