Survey of Turkish systemic lupus erythematosus patients for a particular mutation of C1Q deficiency.
OBJECTIVE
Hereditary C1q deficiency is a rare disease and up to now only 41 cases have been reported. Since all but 3 cases developed SLE or SLE-like disease, C1q deficiency represents the most powerful disease susceptibility gene identified for the development of SLE in humans. A molecular defect in homozygous C1q deficiency has been identified in 13 families. Four of these families are Turkish in origin and they all share the same mutation which is a CAG to TAG change at codon 186 in the A chain. This led us to investigate whether this mutation might be found in Turkish SLE patients and whether it could cause increased disease susceptibility when expressed in the heterozygous form.


METHODS
We screened 65 Turkish lupus patients and 49 healthy Turkish individuals by carrying out an amplification of exon 2 of the A chain and restriction enzyme analysis for the C1qA mutation.


RESULTS
We found no other example of this mutation in either the homozygous or heterozygous forms.


CONCLUSIONS
C1q deficiency is one of the very strong disease susceptibility genes in lupus and may cause SLE via a critical role in the physiological clearance of apoptotic cells. However, C1q deficiency caused by a particular mutation in the A chain in a heterozygous form is not found in the Turkish SLE population.
Topaloglu
R
R
Department of Paediatric Nephrology and Rheumatology, Hacettepe University, Faculty of Medicine, Ankara, Turkey. rtopalog@gen.hun.edu.tr
Bakkaloglu
A
A
Slingsby
J H
JH
Aydintug
O
O
Besbas
N
N
Saatci
U
U
Walport
M J
MJ
D000293:Adolescent; D000328:Adult; D000483:Alleles; D001483:Base Sequence / Q000235:genetics; D002648:Child; D015922:Complement C1q / Q000172:deficiency* / Q000235:genetics*; D005260:Female; D006306:Health Surveys; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D014421:Turkey
D015922:Complement C1q