Infantile neuroaxonal dystrophy

Infantile Neuroaxonal Dystrophy

Autosomal recessive inheritance pattern

Infantile Neuroaxonal Dystrophy (INAD) is a rare, inherited neurodegenerative disorder that primarily affects infants and young children. It is characterized by progressive motor and cognitive decline, leading to severe disability and early death.

Etiology

INAD is caused by mutations in the PLA2G6 gene, which encodes an enzyme involved in the metabolism of phospholipids. This gene is located on chromosome 22. The disorder follows an autosomal recessive inheritance pattern, meaning that both copies of the gene in each cell have mutations.

Pathophysiology

The mutations in the PLA2G6 gene lead to the accumulation of abnormal deposits in the neurons and other cells of the nervous system. These deposits, known as spheroid bodies, disrupt normal cellular function and lead to the degeneration of nerve fibers, particularly in the brain and spinal cord.

Clinical Features

Symptoms of INAD typically begin between 6 months and 3 years of age. Early signs include:

• Developmental delay
• Loss of previously acquired motor skills
• Hypotonia (decreased muscle tone)
• Ataxia (lack of voluntary coordination of muscle movements)
• Optic atrophy leading to vision loss

As the disease progresses, affected children may develop:

• Spasticity
• Seizures
• Dementia

Diagnosis

Diagnosis of INAD is based on clinical evaluation, genetic testing for mutations in the PLA2G6 gene, and neuroimaging studies such as MRI that may show characteristic changes in the brain. A nerve biopsy may reveal the presence of spheroid bodies.

Management

There is currently no cure for INAD, and treatment is primarily supportive. Management focuses on alleviating symptoms and improving quality of life. This may include:

• Physical therapy to maintain mobility
• Medications to control seizures
• Nutritional support

Prognosis

The prognosis for children with INAD is poor. The disease progresses rapidly, and most affected individuals do not survive beyond their first decade of life.

Related Pages

• Neurodegenerative disease
• Autosomal recessive disorder
• PLA2G6-associated neurodegeneration