Nakajo-Nishimura syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Nakajo-Nishimura syndrome is an inherited condition that affects many parts of the body and has been described only in the Japanese population. Beginning in infancy or early childhood, affected individuals develop red, swollen lumps (nodular erythema) on the skin that occur most often in cold weather; recurrent fevers; and elongated fingers and toes with widened and rounded tips (clubbing).

Later in childhood, affected individuals develop joint pain and joint deformities called contractures that limit movement, particularly in the hands, wrists, and elbows. They also experience weakness and wasting of muscles, along with a loss of fatty tissue (lipodystrophy), mainly in the upper body. The combination of muscle and fat loss worsens over time, leading to an extremely thin (emaciated) appearance in the face, chest, and arms.

Other signs and symptoms of Nakajo-Nishimura syndrome can include an enlarged liver and spleen (hepatosplenomegaly), a shortage of red blood cells (anemia), a reduced amount of blood cells called platelets (thrombocytopenia), and abnormal deposits of calcium (calcification) in an area of the brain called the basal ganglia. Intellectual disability has been reported in some affected individuals.

The signs and symptoms of Nakajo-Nishimura syndrome overlap with those of two other conditions: one called joint contractures, muscular atrophy, microcytic anemia, and panniculitis-induced lipodystrophy (JMP) syndrome; and the other called chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome. All three conditions are characterized by skin abnormalities and lipodystrophy. Although they are often considered separate disorders, they are caused by mutations in the same gene, and some researchers believe they may represent different forms of a single condition.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Nakajo-Nishimura syndrome is caused by mutations in the PSMB8 gene. This gene provides instructions for making one part (subunit) of specialized cell structures called immunoproteasomes, which are found primarily in immune system cells. Immunoproteasomes play an important role in regulating the immune system's response to foreign invaders, such as viruses and bacteria. One of the primary functions of immunoproteasomes is to help the immune system distinguish the body's own proteins from proteins made by foreign invaders, so the immune system can respond appropriately to infection.

Mutations in the PSMB8 gene greatly reduce the amount of protein produced from the PSMB8 gene, which impairs the normal assembly of immunoproteasomes and causes the immune system to malfunction. For unknown reasons, the malfunctioning immune system triggers abnormal inflammation that can damage the body's own tissues and organs; as a result, Nakajo-Nishimura syndrome is classified as an autoinflammatory disorder.

Abnormal inflammation likely underlies many of the signs and symptoms of Nakajo-Nishimura syndrome, including the nodular erythema, recurrent fevers, joint problems, and hepatosplenomegaly. It is less clear how mutations in the PSMB8 gene lead to muscle wasting and lipodystrophy. Studies suggest that the protein produced from the PSMB8 gene may play a separate role in the maturation of fat cells (adipocytes), and a shortage of this protein may interfere with the normal development and function of these cells.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Nakajo-Nishimura syndrome appears to be rare and has been described only in the Japanese population. About 30 cases have been reported in the medical literature.

Which doctor should you see?

The suggested department for discussing Nakajo-Nishimura syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Nakajo-Nishimura syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.