C1q deficiency: identification of a novel missense mutation and treatment with fresh frozen plasma

Monogenic lupus with neuroregression in an infant due to rare compound heterozygous variants in C1QA gene: Case-based review

Monogenic lupus is a rare variant of systemic lupus erythematosus (SLE) that develops in patients with a single gene disorder. Early complement component deficiencies were the first forms of monogenic lupus to be described, and C1Q gene mutations are one of the most common forms. C1QA complement deficiency has been reported to occur usually due to biallelic variants in C1QA gene, and compound heterozygous variants in C1QA gene have rarely been reported. A majority of monogenic lupus patients with C1Q deficiency present with mucocutaneous, renal, and musculoskeletal manifestations. Our patient is an unusual case of monogenic lupus with severe neurological manifestations along with cutaneous, haematological, and hepatic manifestations secondary to rare compound heterozygous variants in C1QA gene and antiribosomal P autoantibody positivity. She was treated with glucocorticoids, rituximab, and fresh frozen plasma with partial neurological recovery. Thus, we present a unique case of monogenic lupus due to a rare compound heterozygous variant in C1QA gene with a brief review of literature.

Hematopoietic Stem Cell Transplantation for C1q Deficiency: A Study on Behalf of the EBMT Inborn Errors Working Party

C1q deficiency is a rare inborn error of immunity characterized by increased susceptibility to infections and autoimmune manifestations mimicking SLE, with an associated morbidity and mortality. Because C1q is synthesized by monocytes, to date, four patients treated with allogeneic HSCT have been reported, with a positive outcome in three. We conducted an international retrospective study to assess the outcome of HSCT in C1q deficiency. Eighteen patients, fourteen previously unreported, from eleven referral centres, were included. Two patients had two HSCTs, thus 20 HSCTs were performed in total, at a median age of 10 years (range 0.9-19). Indications for HSCT were autoimmune manifestations not controlled by ongoing treatment in seventeen, and early development of MALT lymphoma in one patient. Overall survival (OS) was 71% and event-free survival was 59% at two years (considering an event as acute GvHD ≥ grade III, disease recurrence and death). In eleven patients HSCT led to resolution of autoimmune features and discontinuation of immunosuppressive treatments (follow-up time range 3-84 months). Five patients died due to transplant-related complications. Patients with a severe autoimmune phenotype, defined as neurological and/or renal involvement, had the worst OS (40% vs 84%; p = 0.034). Reviewing data of 69 genetically confirmed C1q deficient patients, we found that anti-Ro antibodies are associated with neurologic involvement, and anti-RNP and anti-DNA antibodies with renal involvement. In conclusion, HSCT may be a valid curative option for C1q deficiency, but careful selection of patients, with an accurate assessment of risk and benefit, is mandatory.

How to treat monogenic SLE?

Systemic lupus erythematosus is a rare and life-threatening autoimmune disease characterized by autoantibodies against double-stranded DNA, with an immunopathology that remains partially unclear. New insights into the disease have been provided by the discovery of key mutations leading to the development of monogenic SLE, occurring in the context of early-onset disease, syndromic lupus, or familial clustering. The increased frequency of discovering these mutations in recent years, thanks to the advent of genetic screening, has greatly enhanced our understanding of the immunopathogenesis of SLE. These monogenic defects include defective clearance of apoptotic bodies, abnormalities in nucleic acid sensing, activation of the type-I interferon pathway, and the breakdown of tolerance through B or T cell activation or lymphocyte proliferation due to anomalies in TLR signalling and/or NFκB pathway overactivation. The translation of genetic discoveries into therapeutic strategies is presented here, within the framework of personalized therapy.

Case Report: Early Onset Systemic Lupus Erythematosus Due to Hereditary C1q Deficiency Treated With Fresh Frozen Plasma

Background: Hereditary C1q deficiency is associated with early-onset autoimmunity causing SLE or SLE-like disease as well as increased risk for infections with encapsulated bacteria. It is a rare genetic condition inherited in an autosomal recessive manner, caused by mutations in C1q genes. Treatment and management of this rare disease are very complex and include prophylactic vaccination, antibiotics, and immunosuppressive drugs. There are two possible modalities for the replacement of the missing protein: regular fresh frozen plasma (FFP) administration and allogeneic hematopoietic stem cell transplant because the protein is derived from monocytes. Replacing C1q with FFP is being attempted in some patients with success in controlling the disease and in avoiding flare. Case Report: We report a case of sixteen-month-old girl with ulcerations in her mouth, skin erythema, and elevated liver enzymes. ANAs were positive, antibodies against dsDNA were negative, but she had positive anti-Smith antibodies. Complement complements C3 and C4 levels were normal. Total complement activity, classical pathway (hemolytic test) was deficient and C1q antigen was below the detection limit supporting the presence of C1q deficiency. The girl has pathogenic homozygous nonsense mutation in C1qC gene, Arg69Ter (c205>T). The initial response to corticosteroid therapy was good. Regular fresh frozen plasma infusions keep her disease under control, and we were able to reduce the dose of corticosteroids. Conclusion: Young patients with cutaneous lesions resembling SLE, early onset of autoimmunity, with normal C3, C4, elevated ANAs, and negative anti-dsDNA, C1q deficiency should be suspected and complement screening tests should be done. It is important to exclude secondary C1q deficiency. FFP in our patient seems to be well tolerated, without any side effects, able to control the disease.

Bone marrow transplantation from a human leukocyte antigen-mismatched unrelated donor in a case with C1q deficiency associated with refractory systemic lupus erythematosus

Human C1q deficiency is frequently associated with systemic lupus erythematosus (SLE), which requires long-term systemic corticosteroid administration. We report the case of a 12-year-old female patient with C1q deficiency presenting with intractable SLE who successfully underwent bone marrow transplantation from a human leukocyte antigen (HLA)-mismatched unrelated donor with an immunosuppressive conditioning regimen based on fludarabine, melphalan, and anti-thymocyte globulin. She developed Grade I graft-versus-host disease, but did not have any transplantation-related morbidity. Complete donor chimerism has been maintained for 2 years after transplantation, leading to the restoration of C1q levels and the resolution of SLE symptoms. Normal C1q mRNA expression was observed in CD14 + cells. Hematopoietic stem cell transplantation from an HLA-mismatched donor is a feasible treatment for patients with C1q deficiency with refractory SLE that is dependent on systemic corticosteroid treatment who do not have an HLA-matched donor.

Insights Gained From the Study of Pediatric Systemic Lupus Erythematosus

The pathophysiology of systemic lupus erythematosus (SLE) has been intensely studied but remains incompletely defined. Currently, multiple mechanisms are known to contribute to the development of SLE. These include inadequate clearance of apoptotic debris, aberrant presentation of self nucleic antigens, loss of tolerance, and inappropriate activation of T and B cells. Genetic, hormonal, and environmental influences are also known to play a role. The study of lupus in children, in whom there is presumed to be greater genetic influence, has led to new understandings that are applicable to SLE pathophysiology as a whole. In particular, characterization of inherited disorders associated with excessive type I interferon production has elucidated specific mechanisms by which interferon is induced in SLE. In this review, we discuss several monogenic forms of lupus presenting in childhood and also review recent insights gained from cytokine and autoantibody profiling of pediatric SLE.

Systemic lupus erythematosus with C1q deficiency: treatment with fresh frozen plasma

Treatment and outcome of systemic lupus erythematosus (SLE) in C1q deficient patients are rarely reported. The aim of this report is to share our experience about the course of management of three cases diagnosed as SLE with C1q deficiency, in light of present literature. Initial and dominant complaints of three cases from two different families were cutaneous manifestations. One patient was also diagnosed with arthritis and thrombocytopenia. Antinuclear antibody was positive in all cases, whereas anti-dsDNA was negative with normal levels of complement C3, C4 and decreased CH50 activity. C1QA gene of two patients had homozygous nonsense mutation (c.622 > T/p.Gln208Ter). Previously, all of them had been treated with steroids, hydroxychloroquine and methotrexate or azathioprine. It was learned that they had responded only to high dosage prednisolone and their symptoms flared up during dosage reduction even under methotrexate or azathioprine. All symptoms of all three cases improved by daily fresh frozen plasma (FFP) infusions, and once cutaneous lesions subsided, the infusions were reduced to a frequency that would prevent the flare up of the symptoms. Literature search revealed seven reports on fresh frozen plasma treatment in SLE with C1q deficient patients. In this report, it is concluded that severe cutaneous lesions, as seen in these C1q deficient SLE patients, cannot be controlled with conventional immunosuppressive treatment. Instead, regular fresh frozen plasma infusions are proposed as a more reasonable method of treatment.

Marked variability in clinical presentation and outcome of patients with C1q immunodeficiency

OBJECTIVE

Globally approximately 60 cases of C1q deficiency have been described with a high prevalence of Systemic Lupus Erythematosus (SLE). So far treatment has been guided by the clinical presentation rather than the underlying C1q deficiency. Recently, it was shown that C1q production can be restored by allogeneic hematopoietic stem cell transplantation. Current literature lacks information on disease progression and quality of life of C1q deficient persons which is of major importance to guide clinicians taking care of patients with this rare disease.

METHODS

We performed an international survey, of clinicians treating C1q deficient patients. A high response rate of >70% of the contacted clinicians yielded information on 45 patients with C1q deficiency of which 25 are published.

RESULTS

Follow-up data of 45 patients from 31 families was obtained for a median of 11 years after diagnosis. Of these patients 36 (80%) suffer from SLE, of which 16 suffer from SLE and infections, 5 (11%) suffer from infections only and 4 (9%) have no symptoms. In total 9 (20%) of the C1q deficient individuals had died. All except for one died before the age of 20 years. Estimated survival times suggest 20% case-fatality before the age of 20, and at least 50% of patients are expected to reach their middle ages.

CONCLUSION

Here we report the largest phenotypic data set on C1q deficiency to date, revealing high variance; with high mortality but also a subset of patients with an excellent prognosis. Management of C1q deficiency requires a personalized approach.

The identification of a novel splicing mutation in C1qB in a Japanese family with C1q deficiency: a case report

C1q deficiency is a rare disease that is associated with a high probability of developing systemic lupus erythematosus. We report a 4-year-old Japanese girl who presented with fever, facial erythema, joint pain, and oral ulceration. Complement deficiencies were suspected because of her persistent hypocomplementemia and normal levels of the complement proteins C3 and C4. We identified a novel homozygous splicing mutation in the C1qB gene, c.187 + 1G > T, which is the first mutation to be confirmed in a Japanese individual. Because treatment with steroids and immunosuppressive drugs was not effective, we commenced use of fresh frozen plasma to provide C1q supplements. Currently, the patient remains almost asymptomatic, and we are attempting to control the drug dosage and administration intervals of fresh frozen plasma.