Which disorder is associated with loss of mental and movement abilities, particularly in infants?

Leigh Syndrome is particularly associated with a rapid loss of mental and movement abilities, especially in infants. This neurodegenerative disorder primarily affects the central nervous system and is characterized by progressive neurological decline, muscle weakness, and severe developmental delay. Infants diagnosed with Leigh Syndrome often present with symptoms such as respiratory distress, feeding difficulties, hypotonia, and seizures, which are indicative of the disorder’s impact on cognitive and motor functions.

The condition is typically caused by genetic mutations that affect mitochondrial function, leading to impaired energy production within cells. The symptoms usually appear after a period of normal development, making it alarming for families as they witness their child's rapid decline.

Other listed conditions also involve neurological symptoms but are not primarily noted for the same abrupt onset of cognitive and motor decline in infants. For instance, MELAS syndrome involves features like muscle weakness and stroke-like episodes, but it may not manifest as early as Leigh Syndrome or show such rapid progression in infants. Similarly, MERRF presents with myoclonus, seizures, and ataxia but typically has a later onset. Thus, while all mentioned disorders have neurological manifestations linked to mitochondrial dysfunction, Leigh Syndrome stands out for its specific association with early-onset loss of such abilities in infants.