Monogenic disorders as mimics of juvenile idiopathic arthritis

Table 1 Comparison of the major clinical features of the cases

Case	Condition	Characteristics	Present in our patient	Diagnostic delay (years)	Inheritance	History of consanguinity	Gene and variant description	Inflammatory markers	Imaging
1	MCTO	Osteolysis of Carpo-tarsal bones	+	12 years	AD	No	MAFB c.176C > T; pPro59Leu	CRP 1 – 6 mg/L ESR 2-6 mm/1st	x-ray
		Renal involvement	–					hour^a	bilateral dissolution of bones in hands and feet
		Corneal clouding	–
		Craniofacial abnormalities	–
		Other manifestations (i.e skin deposit)	+
2	CACP	Camptodactly	+	7	AR	Yes	PRG4 c.3462_3465delGACT;p.Thr1155LeufsTer7	ESR 1 -25 mm/1st hour	x-ray bilateral coxa vara with shallow acetabular and periarticular osteopenia^b US bilateral effusions of hips and knees MRI short and broad femoral necks with minimal enhancement with ring pattern and synovial thickening
		Arthropathy	+
		Coxa vara	+
		Pericarditis	+
3	CACP	Camptodactly	–	12	AR	Yes	PRG4 c.2998_3001delAAAC;p.Lys1000LeufsTer43	ESR 1 – 9 mm/1st hour
		Arthropathy	+
		Coxa vara	+
		Pericarditis	–
4	Blau syndrome	Granulomatous		Unknown	AD	No	CARD15 (NOD2) c.1001G > A;p.Arg334Gln	Typically raised	No imaging available for this case
		Arthritis	+
		Uveitis	Unknown
		Dermatitis	Unknown

^aESR noted to be 40 mm/1st hour on one occasion with intercurrent viral illness
^bOsteopenia noted to be less severe than what is expected in JIA by reporting radiologist

ISSN: 1546-0096