ISSN:
1573-2592
Keywords:
C4 deficiency
;
complement
;
systemic lupus erythematosus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Although null alleles of complement C4 genes (C4A *Q0 andC4B *Q0) are frequent in the normal population, the occurrence of two null alleles on the same chromosome is very rare and therefore complete C4 deficiency is exceptional. We describe a 16-year-old North African boy who presented with systemic lupus erythematosus with renal involvement and persistent undetectable classical pathway activity and C4 protein and hemolytic activity in plasma, with normal C3 levels. Similar complement abnormalities were observed in his healthy 12-year-old brother. Complete C4 deficiency was documented in the two brothers by investigation of the family and the lack of C4A and C4B bands upon phenotyping of C4. Southern blot analysis of the C4/CYP21 gene organization in the family indicated that the deficiency resulted from a deletion of the C4B/CYP21A genes associated with nonexpression of a C4A gene. The double-null haplotype was found to be associated with homozygous A2 B17 C2C BFF C4 AQO BQO DR7 HLA haplotype. Thus, similar C4 deficiencies with HLA identity may lead to different clinical presentations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01540980
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