Subtotal C4 deficiency and SLE-like disease.

Extremely low C4 values were found in a 65-year-old man with relapsing arthritis and skin lesions of many years duration of the scalp, face, hands and feet together with painful ulcerations of the toes and fingers. The discovery was made during an exacerbation, but the deficiency of C4 persisted in repeated controls after remission. The clinical findings in connection with these low C4 values are in congruence with the diagnosis of inherited deficiency of C4.