Homozygous hereditary C1q deficiency and systemic lupus erythematosus: A new family and the molecular basis of C1q deficiency in three families

✍ Scribed by Jason H. Slingsby; Peter Norsworthy; Glen Pearce; Akshay K. Vaishnaw; Helen Issler; Bernard J. Morley; Mark J. Walport

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 739 KB
• Volume: 39
• Category: Article
• ISSN: 0004-3591
• DOI: 10.1002/art.1780390419

✦ Synopsis

Objective. To describe a new kindred with Clq deficiency and to identify the molecular lesions responsible for complete functional Clq deficiency in this and 2 other previously described kindreds.

Methods. The A-, B-, and C-chain genes of Clq were amplified by polymerase chain reaction, cloned, and sequenced. The DNA sequence was checked for mutations.

Results. Patient 1 had a homozygous G-to-A change at codon 6 of the C chain, causing an amino acid change from Gly to Arg. Patient 2 had a homozygous deletion of a C nucleotide at codon 43 of the C-chain, causing a frame shift, leading to a premature stop codon at codon 108. Patient 3 had a homozygous C-to-T mutation at amino acid position 41 of the C chain, resulting in a premature stop codon.

Conclusion.

In the homozygous state, the mutations are sufficient to cause complete deficiency of Clq. The mutation in patient 1 has been previously reported in a patient of different ethnic origin. A survey of a series of 158 DNA samples from patients with systemic lupus erythematosus showed no other examples of this mutant allele.

Homozygous C l q deficiency has been described in 30 people, 28 of whom had systemic lupus