Nakajo syndrome

Autosomal recessive - en

Nakajo syndrome is a rare autoinflammatory disease that primarily affects the skin, muscles, and nervous system. It is also known as Nakajo-Nishimura syndrome or nodular erythema with digital clubbing and joint contractures. The condition was first described in Japan by Dr. Nakajo in 1939.

Presentation

Nakajo syndrome typically presents in infancy or early childhood. The initial symptoms often include recurrent fever, nodular erythema, and digital clubbing. As the disease progresses, patients may develop muscle atrophy, joint contractures, and lipomuscular atrophy. Other common features include hepatosplenomegaly, lymphadenopathy, and peripheral neuropathy.

Genetics

Nakajo syndrome is inherited in an autosomal recessive manner. Mutations in the PSMB8 gene have been identified as the cause of the disease. The PSMB8 gene encodes a subunit of the immunoproteasome, which is involved in the degradation of ubiquitinated proteins. Mutations in this gene lead to the accumulation of damaged proteins, triggering an inflammatory response.

Diagnosis

The diagnosis of Nakajo syndrome is based on clinical features, family history, and genetic testing. Skin biopsy and muscle biopsy may show characteristic histopathological findings, such as granulomatous inflammation and lipomuscular atrophy. Genetic testing can confirm the presence of mutations in the PSMB8 gene.

Treatment

There is no cure for Nakajo syndrome, and treatment is primarily supportive. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids may be used to manage inflammation and pain. Physical therapy can help maintain joint mobility and muscle strength. In some cases, immunosuppressive therapy may be considered.

Prognosis

The prognosis for individuals with Nakajo syndrome varies. Some patients may experience a relatively mild course, while others may develop severe complications, such as respiratory failure or cardiomyopathy. Early diagnosis and appropriate management can improve the quality of life for affected individuals.

Related Pages

• Autoinflammatory disease
• Digital clubbing
• Muscle atrophy
• Peripheral neuropathy
• PSMB8