Congenital Deficiency of C2 and Factor B

To the Editor: Recently, Newman et al.¹ reported decreased levels of properdin factor B in three homozygous C₂-deficient children, an association attributed to the linkage between genes coding for the two proteins. The authors cite the papers by Glass² and Raum³ and their colleagues as in agreement. In the paper by Glass et al.² the only person with homozygous C₂ deficiency, a patient with systemic lupus erythematosus, had a factor B level of 320 μg per milliliter, which was within the normal range. This paper reported a statistical difference in factor B levels between heterozygous C₂-deficient and normal family members.