Objective: To study the frequency and clinical features of chronic inflammatory arthritis in aspartylglucosaminuria (AGU), a rare disorder of glycoprotein degradation inherited as an autosomal recessive trait and significantly more frequent in Finland than in other parts of the world.
Methods: Of the 164 patients with AGU identified in Finland, 121 were examined by one of the authors, and 43 by their own physicians. For this study, we clinically reexamined all patients with AGU who had arthritis, and relevant laboratory and radiographic studies were performed.
Results: Nine of 164 patients (5.5%) were found to have chronic inflammatory arthritis. In 5 patients, the symptoms had started in childhood. Five were seropositive for rheumatoid factor. Symmetric polyarthritis of both small and large joints was seen in 5 patients and erosions in 5. Seropositive rheumatoid arthritis was found in 3 first-degree relatives as well.
Conclusion: Chronic inflammatory arthritis is a feature of AGU and is characterized by onset in childhood, seropositivity for rheumatoid factor, and a deforming course.