Related Experiment Video

Updated: Jun 30, 2026

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila
06:41

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila

Published on: August 20, 2019

Common and rare variants in complement genes as biomarkers of COVID-19 infection and severity. A lesson to learn for

María Eugenia De La Morena-Barrio1,2, Ana Van Den Rym3,4,5, Olga Escorial Sanz6

  • 1Servicio de Hematología, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB)-Arrixaca, Murcia, Spain.

Frontiers in Immunology
|June 29, 2026
PubMed

Insights

Genetic variants in the complement system influence susceptibility to severe COVID-19. Specific complement gene polymorphisms offer potential biomarkers for predicting disease severity and preparing for future infectious threats.

Area of Science:

  • Immunogenetics
  • Infectious Disease Epidemiology

Background:

  • The first wave of COVID-19 significantly impacted Spain, with high infection and mortality rates.
  • While genetic factors influencing immune responses are known, the role of the complement system in COVID-19 susceptibility and severity remains understudied.

Purpose of the Study:

  • To investigate the association of complement system-related genetic variants with severe COVID-19 in a Spanish cohort.
  • To identify potential genetic biomarkers for predicting COVID-19 severity and future pandemic preparedness.

Main Methods:

  • Analysis of whole-exome sequencing data from 154 hospitalized severe COVID-19 patients.
  • Examination of common polymorphisms and rare variants within complement genes.

Main Results:

  • Common polymorphisms in CFHR4 (rs7417769) and CFH (rs1061170) were linked to protection against acute respiratory distress syndrome (ARDS).
  • C3 (rs2230199) and MASP2 (rs7255087) polymorphisms correlated with C3 levels.
  • Variants in C1R and C8A, and alleles affecting FCN2/FCN3 levels, suggested a role for defective complement activation and the lectin pathway in COVID-19 pathogenesis.

Conclusions:

  • Common variants in complement genes significantly modulate susceptibility to severe COVID-19 and its complications.
  • Identified genetic biomarkers may aid in managing SARS-CoV-2 and preparing for emerging infectious diseases.
Abstract

Keywords:
ARDS (acute respiratory disease syndrome)COVID- 19complement systemgenetic variationinnate immunity

More Related Videos

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

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation07:15

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Published on: January 16, 2019

Related Concept Videos

Single Nucleotide Polymorphisms-SNPs01:05

Single Nucleotide Polymorphisms-SNPs

A single nucleotide polymorphism or SNP is a single nucleotide variation at a specific genomic position in a large population. It is the most prevalent type of sequence variation found in the human genome. Point mutations that occur in more than 1% of the population qualify as SNPs. These are present once every 1000 nucleotides on an average in the human genome. Replacement of a purine with another purine (A/G) or a pyrimidine with another pyrimidine (C/T) is known as a transition. In contrast,...
Principles of Pharmacogenetics: Types of Genetic Variants01:27

Principles of Pharmacogenetics: Types of Genetic Variants

The human genome is over 99.9% identical between individuals, yet genetic differences exist at millions of bases. The human genome contains approximately 3 million variant positions per individual, many of which are heterozygous, contributing to genetic diversity and individual traits. Genetic variations include single-nucleotide polymorphisms (SNPs), insertions, deletions, and copy number variations (CNVs).SNPs, the most common variation, involve single-base changes in DNA. These can be...
Comparing Copy Number Variations and SNPs02:26

Comparing Copy Number Variations and SNPs

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist within a population. These variations can be a single nucleotide or a larger chromosomal variation.
Copy number variations or CNVs are the structural variations that cover more than 1kb of DNA sequence. The single nucleotide polymorphism (SNP), on the other hand, is a single nucleotide change or a point mutation that is found in more than 1%...
Complement System01:27

Complement System

The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...
Complementation Tests00:49

Complementation Tests

A complementation test is a simple cross to identify whether the two mutations are located on the same gene or different genes. It was first performed by Edward Lewis in the 1940s while working on fruit flies. He developed the test to identify the location and arrangement of different mutations on chromosomes.
Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...
Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu01:29

Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu

Genetic variations significantly influence drug response through pharmacokinetics, receptor interactions, and biologic milieu modifications. Pharmacokinetic alterations impact drug metabolism and clearance, affecting efficacy and toxicity. Variants in drug-metabolizing enzymes, such as CYP2C9 and CYP2C19, alter drug activation and elimination. For example, CYP2C9 loss-of-function variants require lower warfarin doses to prevent excessive bleeding, while CYP2C19 variants reduce clopidogrel...