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. CONCLUSION: 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.
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 SLEpatients and whether it could cause increased disease susceptibility when expressed in the heterozygous form. METHODS: We screened 65 Turkish lupuspatients 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. CONCLUSION: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.