Novel Pathogenic C2 Variant Associated with Disseminated GBS Infection
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LETTER TO EDITOR
Novel Pathogenic C2 Variant Associated with Disseminated GBS Infection Emma C. Phillips 1 & Monica Gupta 2 & Rung-Chi Li 2 & Julia K. Sohn 2 & Monica G. Lawrence 2 Received: 11 December 2019 / Accepted: 27 April 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
To the Editor: The complement system comprises several proteins of the innate immune system that assist in host cell phagocytosis, generation of inflammation, and membrane attack. As complement activation plays a major role in host defense against encapsulated bacteria, deficiencies in any one of these 30+ proteins can result in serious infections by organisms such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis [1]. The most common hereditary complement deficiency in Caucasians (1 in 10,000 individuals) is in the C2 protein [1]. We report a previously healthy Caucasian female who was born at 37 weeks’ gestation with no neonatal distress or neonatal infection history to a group B Streptococcus (GBS)-negative mother. She presented to the emergency department (ED) at 11 weeks of age with fever, congestion, and 1 day of intermittent episodes of gasping associated with apnea and oral and hand cyanosis. In the ED, she developed a seizure without fever. She was admitted to the inpatient ward, and blood and cerebrospinal fluid (CSF) cultures grew GBS. No white blood cells were noted on the CSF gram stain although the protein was elevated at 31 mg/dL and the glucose was low at 50 mg/dL. Laboratory studies done while hospitalized were notable for undetectable total hemolytic complement (CH50) (< 12 U/mL, normal 42–95 U/mL) with normal alternative pathway complement function (AH50) (50%, normal ≥ 46%). She was also found to have elevated IgM (110 mg/ Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10875-020-00784-9) contains supplementary material, which is available to authorized users. * Monica G. Lawrence [email protected] 1
University of Virginia School of Medicine, Charlottesville, VA, USA
2
Department of Medicine, Division of Asthma, Allergy & Immunology, University of Virginia, Charlottesville, VA, USA
dL, normal 6–21 mg/dL), absent IgE (< 2 IU/mL), normal IgA (19 mg/dL, normal 1–34 mg/dL), and normal IgG (360 mg/dL, normal 203–934 mg/dL). Peripheral blood flow cytometry was unremarkable except for mildly reduced CD8+ cytotoxic T cells. After several days of treatment, the infection resolved and the patient was discharged to complete 21 days of intravenous penicillin G. Subsequent studies conducted 2 weeks after admission confirmed the undetectable CH50; however, low or undetectable CH50 has been noted in the setting of acute infection or shortly after recovery so follow-up studies were pursued 2 months later. Immunoglobulins normalized with the exception of IgE which remained low for age at 3.6 IU/ mL (normal 8–144 IU/mL). C2 level was markedly reduced at 0.2 mcg/mL (< 1% of normal). Genetic testing via targeted 75-gene complement diso
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