Mitochondrial Diseases 1962 – Inherited Only from the Mother

Most cells in our bodies contain remnants of bacteria that entered cells more than a billion years ago and helped complex life forms like us emerge. These miniature cellular powerhouses, known as mitochondria, produce much of the adenosine triphosphate (ATP) needed to supply cellular energy. However, mitochondria do more than generate energy: they influence processes ranging from bodily aging to the specialized functions of different cells. They also help with detoxification and the synthesis of biologically important compounds. 

A single body cell can contain hundreds of mitochondria, each carrying 37 mitochondrial genes in its own small, circular, double-stranded DNA, of which several copies are present. Mitochondria behave somewhat like microorganisms and divide independently of the rest of the host cell.

Mitochondrial diseases (MDs) result from malfunctioning mitochondria, usually because of mutations in the mitochondrion's own DNA (mtDNA) or in the host cell's DNA that contributes to mitochondrial structure and function. 

MDs are highly varied, and symptoms may include:

• Loss of muscle function
• Vision problems or loss
• Hearing problems
• Delayed mental development
• Poor growth

MDs also affect programmed cell death and consequently conditions known as “diseases of aging”. These include:

• Dementia
• Type 2 diabetes
• Parkinson's disease
• Cancer
• Heart disease

The distribution of abnormal mitochondria can vary between organs and can also change as mitochondria multiply within cells. MDs become clinically apparent when the number of defective mitochondria in cells exceeds a threshold. Unlike many other genetic diseases caused by defective genes from parents, mtDNA comes only from the egg cell and is therefore inherited only from the mother.

In 1962, the Swedish endocrinologist Rolf Luft and his colleagues described the nature of an MD after studying a woman with malfunctioning mitochondria. Energy was being wasted as heat. She suffered from weight loss and muscle weakness, could not stop sweating and constantly felt hot.

About the Article Image: An artistic representation of a mitochondrion revealing its internal compartments. The red inner mitochondrial membrane forms folds known as cristae.

Historical Figures Mentioned in the Article: Rolf Luft (1914–2007)

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