An inherited disorder characterized by recurrent fever and peritonitis and less frequently by pleuritis, arthritis, skin lesions, and pericarditis. A sufficient number of cases have occurred in other groups, particularly Ashkenazic Jews, to caution against excluding the diagnosis on the basis of atypical ancestry. The gene product, a 781 amino acid protein called pyrin by one group of discoverers and marenostrin by another, appears to be expressed only in circulating neutrophils. It is believed to attenuate the transcription of proinflammatory promoters by these cells. Symptoms, Signs, and Diagnosis Onset is usually between the ages of 5 and 15 but may be much later or even during infancy.
Attacks have no regular pattern of recurrence and vary in the same patient.
Severity and frequency tend to decrease with age, during pregnancy, or with amyloidosis. Spontaneous remissions may last years. Decreased bowel sounds, distention, guarding, and rebound tenderness are likely to occur at the peak of an attack and cannot be differentiated from a perforated viscus on physical examination. Consequently, many patients have undergone urgent laparotomy before the correct diagnosis was made. With diaphragmatic involvement, splinting of the chest and pain in one or both shoulders may occur.