Beneficial effect of methotrexate on a child case of Nakajo-Nishimura syndrome

A Chinese case of Nakajo-Nishimura syndrome with novel compound heterozygous mutations of the PSMB8 gene

Background

Nakajo-Nishimura syndrome (NNS) is an autosomal recessive heredity disorder, one of a spectrum of autoinflammatory diseases named proteasome-associated autoinflammatory syndrome (PRAAS) caused by mutations of PSMB8 gene. NNS is characterized by pernio-like skin rashes, intermittent fever, and long clubbed fingers and toes with joint contractures, partially with progressive lipomuscular atrophy, emaciation, hepatosplenomegaly and basal ganglion calcification.

Case presentation

We presented a sporadic case of NNS with compound heterozygous mutations in the PSMB8 gene. The 4-year-old boy was affected by progressive erythematous plaques on his nose and gradually involved hands and feet later with characteristic appearance of long clubbed fingers. The repetitive periodic intermittent fever was recorded. By gene sequencing, novel compound heterozygous mutations c.373C > T (p.R125C) and c.355G > A (p.D119N) in the PSMB8 gene were found. The patient responded well to low dosage of oral methylprednisolone.

Conclusions

We reported novel compound heterozygous mutations in PSMB8 in a sporadic Chinese NNS patient.

Nakajo-Nishimura syndrome and related proteasome-associated autoinflammatory syndromes

Nakajo-Nishimura syndrome (NNS) is a rare hereditary autoinflammatory disorder with lipodystrophy. This disease is caused by a homozygous mutation of PSMB8 gene, which encodes immunoproteasome subunit β5i. Phenotypes of NNS patients are periodic fever, pernio-like rash, nodular erythema-like eruptions, and lipomuscular dystrophy, especially in the upper body, leading to the characteristic long, clubbed fingers. NNS was considered to be endemic to the Kansai area of Japan, but patients with similar phenotypes and the mutation of PSMB8 gene were reported in other countries, and named Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome and joint contractures, muscular atrophy, microcytic anemia, and panniculitis-associated lipodystrophy (JMP) syndrome. These syndromes are now called proteasome-associated autoinflammatory syndromes (PRAASs), and their main pathophysiological mechanism seems to be interferonopathy. In this review, the history, characteristics, and the pathophysiological mechanism of PRAASs will be discussed, focusing mainly on NNS.