Of the 17 undifferentiated patients: 7 were males > 6 years, HLAB27 positive with a family history of psoriasis; 8 were oligo or poly arthritis with a family history of psoriasis with no other features; 2 were oligoarthritis with B27 and rheumatoid factor (RF) positivity. The gene discussed is MRAP; the disease is Arthritis.