Rare Nephrology News

Disease Profile

C1q deficiency

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable



Congenital and Genetic Diseases; Immune System Diseases


C1q deficiency is a rare disorder associated with recurrent skin lesions, chronic infections, systemic lupus erythematosus (SLE) or SLE-like diseases. It has also been associated with a kidney disease known as mesangial proliferative glomerulonephritis. C1q is a protein and together with other proteins, C1r and C1s, it forms the C1 complex. This complex is important for the activation of the complement system (a group of proteins that work with the immune system). It also disposes cells that are dead. C1q deficiency presents in 2 different forms, absent C1q protein or abnormal C1q protein.[1] Symptoms include infections (ear infections (otitis media), meningitis, urinary tract infections, oral infections); skin lesions (small blisters (vesicles), dark patches, and atrophic areas) that get worse upon light exposure; cataracts; loss of eyelashes, eyebrows, and scalp hair; blood in urine; and glomerulonephritis. About 93% of cases are associated with systemic lupus erythematosus.[1][2] It can be caused by mutations in the C1QA, C1QB or C1QC genes and is inherited in an autosomal recessive pattern.[3] Treatment depends on the symptoms. Recently, it was shown that C1q production can be restored by allogeneic hematopoietic stem cell transplantation, a procedure in which a person receives blood-forming stem cells (cells from which all blood cells develop) from a genetically similar, but not identical donor.[1]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
5%-29% of people have these symptoms
Membranoproliferative glomerulonephritis
Systemic lupus erythematosus
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
Decreased serum complement factor I
Recurrent infections
Frequent infections
Frequent, severe infections
Increased frequency of infection
infections, recurrent
Predisposition to infections
Susceptibility to infection

[ more ]



Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Providing General Support

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    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    In-Depth Information

    • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
    • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.


      1. van Schaarenburga RA & cols. Marked variability in clinical presentation and outcome of patients with C1q immunodeficiency. J Autoimmun. August, 2015; 62:39-44. https://www.ncbi.nlm.nih.gov/pubmed/26119135.
      2. C1q deficiency. OMIM. June, 2015; https://omim.org/entry/613652.
      3. Schwartz RA. Complement Deficiencies. Medscape Reference. February 23, 2015; https://emedicine.medscape.com/article/135478-overview.