Related Experiment Video

Updated: Aug 16, 2026

Extraction of Tissue Antigens for Functional Assays
08:32

Extraction of Tissue Antigens for Functional Assays

Published on: September 10, 2012

Genetic polymorphism of the fourth component of complement and type 1 (insulin-dependent) diabetes

A Marcelli-Barge, J C Poirier, M Schmid

    Diabetologia
    |July 1, 1984
    PubMed

    Insights

    The C4BQ0 complement variant is more common in Type 1 diabetes patients, especially those with HLA-DR3 or HLA-DR4. This finding suggests a link between complement deficiencies and immune response in diabetes.

    Area of Science:

    • Immunogenetics
    • Molecular Biology
    • Human Genetics

    Background:

    • Complement proteins (Bf, C2, C4A, C4B) are genetically linked to the Human Leukocyte Antigen (HLA) complex.
    • A null allele (C4BQ0) at the C4 B locus is associated with impaired immune responses.
    • Type 1 diabetes has known associations with specific HLA alleles.

    Purpose of the Study:

    • To investigate the incidence of the C4BQ0 variant in Type 1 diabetes patients and their families.
    • To determine the association of C4BQ0 with specific HLA alleles (DR3, DR4) in Type 1 diabetes.
    • To explore linkage disequilibrium between complement and HLA genes in affected individuals.

    Main Methods:

    • Genotyping for HLA-A, -B, -C, and -DR loci.
    • Analysis of complement factor B (Bf) and C4 phenotypes, including C4BQ0.
    • Statistical analysis comparing allele frequencies and linkage disequilibrium in patients and controls.

    Main Results:

    • A significantly higher incidence of C4BQ0 was observed in Type 1 diabetes patients (33%) compared to controls (12%).
    • C4BQ0 was more frequent in affected individuals (propositi) than in their non-affected siblings.
    • The C4BQ0 phenotype was significantly more prevalent in Type 1 diabetes patients carrying HLA-DR3 (56%) or HLA-DR4 (25%) alleles.

    Conclusions:

    • The C4BQ0 variant is strongly associated with Type 1 diabetes, particularly in individuals with specific HLA-DR alleles.
    • These findings highlight the role of complement system variations in the immunopathogenesis of Type 1 diabetes.
    • The study identifies significant linkage disequilibria between specific HLA and complement alleles in Type 1 diabetes patients.

    More Related Videos

    Accelerated Type 1 Diabetes Induction in Mice by Adoptive Transfer of Diabetogenic CD4+ T Cells06:27

    Accelerated Type 1 Diabetes Induction in Mice by Adoptive Transfer of Diabetogenic CD4+ T Cells

    Published on: May 6, 2013

    High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment07:26

    High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment

    Published on: July 18, 2017

    Related Concept Videos

    Diabetes Mellitus: Overview and Type I Subtype01:22

    Diabetes Mellitus: Overview and Type I Subtype

    Diabetes mellitus is a chronic metabolic disorder characterized by high blood glucose levels due to inadequate insulin production, insulin resistance, or both. The condition affects millions worldwide and can significantly impact their health and quality of life.
    Type 1 diabetes is an autoimmune disease in which the immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. As a result, the body is unable to produce sufficient insulin, and individuals with...
    Diabetes Mellitus: Type 2 and Gestational01:22

    Diabetes Mellitus: Type 2 and Gestational

    Type 2 diabetes, characterized by insulin resistance, arises when the insulin receptors on cells lose responsiveness to insulin, diminishing the cell's capacity to take up glucose, resulting in elevated blood glucose levels. To receive a diagnosis of Type 2 diabetes, a series of blood glucose tests are necessary to assess whether the blood glucose falls within normal parameters. If the result is out of the normal range, a patient may be diagnosed as prediabetic or diabetic, depending on the...
    Pathophysiology of Diabetes01:20

    Pathophysiology of Diabetes

    Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycemia. The four categories of diabetes are type 1 diabetes, type 2 diabetes, other specific types of diabetes, and gestational diabetes.
    Type 1 diabetes is characterized by autoimmune-mediated destruction of pancreatic β cells, with environmental factors potentially triggering this process in genetically susceptible individuals. Despite many not having a family history, certain genes increase susceptibility, suggesting a...
    Type I Diabetes I: Introduction01:12

    Type I Diabetes I: Introduction

    Type 1 diabetes mellitus is a chronic metabolic disorder characterized by an absolute deficiency of insulin resulting from the autoimmune destruction of pancreatic β-cells. Although it can occur at any age, it is most commonly diagnosed in childhood, adolescence, or early adulthood. The loss of insulin production impairs cellular glucose uptake, resulting in persistent hyperglycemia and necessitating lifelong insulin therapy.Autoimmune Destruction of β-CellsThe hallmark of type 1 diabetes is an...
    Type I Diabetes II: Pathophysiology01:26

    Type I Diabetes II: Pathophysiology

    Type 1 diabetes mellitus arises from an immune-mediated destruction of pancreatic β-cells, resulting in an absolute deficiency of insulin. This process develops in genetically susceptible individuals when autoimmunity, environmental exposures, and immunologic dysregulation converge to trigger a targeted attack on the insulin-producing cells of the pancreas. The β-cells are located within the islets of Langerhans and are essential for regulating blood glucose by facilitating cellular uptake of...
    Type II Diabetes I: Introduction01:26

    Type II Diabetes I: Introduction

    Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance, in which target tissues such as the liver, muscle, and adipose tissue respond poorly to insulin. It is also associated with inadequate compensatory insulin secretion, where pancreatic β-cells fail to produce sufficient insulin. Together, these abnormalities lead to persistent hyperglycemia.EtiologyT2DM develops through a complex interaction of genetic predisposition and environmental or...