Final answer:
The child's symptoms and metachromatic staining indicate Metachromatic Leukodystrophy (MLD), a genetic disorder caused by a deficiency of the enzyme arylsulfatase A, leading to demyelination in the nervous system.
Step-by-step explanation:
The case described is a 2-year-old with gait disturbance, loss of intellectual function, nystagmus, and optic atrophy. The metachromatic staining with cresyl violet indicates the presence of abnormal cellular components that stain differently from normal tissue. This set of symptoms and the metachromatic staining are characteristic of a leukodystrophy known as Metachromatic Leukodystrophy (MLD).
Metachromatic Leukodystrophy is caused by a deficiency of the enzyme arylsulfatase A, leading to the accumulation of sulfatides within lysosomes. This accumulation affects the myelin sheath of nerve cells, leading to demyelination and the neurological symptoms noted in the patient's presentation. A geneticist would be involved in diagnosing and managing the condition, as this is an inherited disorder, often tested for through genetic testing.