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Immunology in CDG


In this section:

  • What is the immune system and why is it important?

  • How does the immune system work?

  • Immunological (Dys)functioning in CDG

  • How can immune-related manifestations be diagnosed and managed?

  • Are there any treatments?

What is the immune system and why is it important?

The immune system consists of a network of special cells, tissues (group of connected cells), and organs (collection of tissues) that work together to protect the body (See picture below). It is responsible for defending our body against microorganisms (tiny organisms invisible to the eye), unhealthy cells and distinguishes our cells (self) from foreign cells (non-self). Usually, it does a great job at keeping people healthy and preventing infections, but sometimes problems with the immune system can lead to autoimmunity (our own organism attacks itself), allergies and infection.

Osmosis offers a video with an introduction to the immune system:

Major organs of the immune systems

How does the immune system work?

When a microorganism manages to get through our physiological barriers and is detected, innate immune cells (See Figure Bellow - blue circle) will immediately start working together to recognize it and to respond accordingly, neutralising or destroying the threat. Innate immune cells activate specialised immune cells (cells from the adaptive response (orange circle), namely B cells and T cells (check explanatory image below): 

  • B cells produce antibodies (or immunoglobulins – Ig), which are specialised proteins that bind specifically to a microorganism. There are different types of antibodies (IgG, IgM, IgA, IgE and IgD) with distinct immune functions. 
  • T cells (Figure - orange circle) kill cells that have been infected or somehow changed (e.g. become malignant). T cells do this by releasing specific killing substances and by recruiting other immune cells, like B cells, to act.
Cells of the innate and adaptive immune responses

A glossary done with you and for you is available at:

Immune System.pdf

The 2 types of immune response have different functions:

innate adaptive immune response

All the immune systems offer the body protection against disease, by coordinating their actions and communicating with each other, thus conferring immunity to our bodies. 
The figures below give an overview of the immune system’s features in a simplified manner.

Overview of the immune system

But what are the antibodies’ main functions?

The next figure shows how antibodies fight microorganisms. Importantly, after eliminating an infection, antibodies may remain for days or months in the organism, providing protection to fight future infections by the same pathogen. This process is called immunological memory. 

Antibodies’ main functions

An introductory video by KidsHealth explains how the immune system works, you can assist HERE:


 To get more information about the immune system, visit our immunology booklet at the link below:

Immunology Patient Friendly.pdf

For additional resources on the immune system and the nomenclature:

Immune Alterations.pdf

To complement your understanding about the immune system watch the video provided by Zero to Finals:

To better understand what happens after an infection in your body, watch this video from the Kurzgesagt – In a Nutshell:


To better understand what happens after a bacterial infection in your body, watch this video from the Kurzgesagt – In a Nutshell: 

Immunological (Dys)functioning in CDG

In 2019, CDG & Allies conducted a literature review and identified several CDGs with abnormal immunological functioning as a distinguishing clinical feature (check table below). This happens because glycans (sugar athenas) are necessary for the human body to identify enemies, communicate between cells, and make strategic decisions when the body needs to defend itself. Glycans attach to immune cells via the glycosylation mechanism (a process that adds sugars to proteins and lipids), which is defective, abnormal or absent, in people who live with CDG. Furthermore, CDGs are complex diseases with a lot of heterogeneity even within the same type, so it is possible to divide CDGs into two groups based on the degree of immunological involvement:

immunologycal involvement

Still, this subdivision is poorly understood due to a lack of knowledge regarding the clinical features of each CDG type throughout a person's growth (from onset to eventual passing) as well as the underlying mechanisms for these immunological anomalies.

For more information on the immunological involvement of each CDG in the table above, access the full article by clicking HERE.

In the case of PMM2-CDG, infections and/or other immune-related manifestations have been reported in a number of patients, with infections being the most common problem. They are recurrent and mostly predominant during early life and childhood and become less frequent and severe in adolescence and adulthood. Although infections tend to affect in a larger scale the respiratory and gastrointestinal tracts, sometimes they can progress to more generalised and severe manifestations known as sepsis (infection which provokes an exaggerated response of the organism) or septic shock (last and most severe stage of sepsis). This is one of the reasons why infections lead to premature death in young PMM2-CDG children.

Please read the full article titled "New Insights into Immunological Involvement in Congenital Disorders of Glycosylation (CDG) from a People-Centric Approach" for more information on the immune aspect of PMM2-CDG by clicking HERE

Find below a list of the main immune-related manifestations, beside infections,  found in PMM2-CDG:

n immune-related manifestations

 For more information, watch this video brought to you by one of the former CDG & Allies research members, which explains the impact that CDG has on the immune system and its consequences.

How can immune-related manifestations be diagnosed and managed?

To effectively detect any of these manifestations, the following tests should be done at the time of the diagnosis and/or if you/your child suffer from recurrent infections: 

  • Leukogram- It is the count of white blood cells (WBC), including neutrophil, lymphocyte and natural killer (NK) cells, present in blood. Counts that are higher or lower than reference values are indicative of infection and immunodeficiency, respectively. This test is often included with a complete blood count (CBC)7;
  • Immunoglobulin count (including IgA, IgG, and IgM counts) -  measurement of the level of types of antibodies in the blood. The immune system makes antibodies to protect the body from bacteria, viruses, and allergens8. 

These tests should be repeated from time to time, especially during infancy, and/or if you or your doctor suspect of an infection.

Where do we stand concerning CDG and vaccination? 

People who live with CDG may not respond to vaccines. After vaccination, you/your child should measure the levels of protective antibodies (known as antibody titers9 - a type of blood test that determines the presence and level of antibodies in the blood). This test is carried out to investigate if there is an immune reaction triggered by foreign invaders (antigens) in the body. Also, if you/your child have any adverse reaction to a vaccine (e.g., fever, seizure) you should contact your clinician/clinical team ASAP.
Important Fact: If you/your child are diagnosed with an infection, it is important that you get close monitoring by your clinician to prevent complications and eventual sepsis. This is especially relevant in young infants and children.
For additional resources, you can find in this glossary some information about  immunological tests.

Immunological Tests.pdf

Are there any treatments?

There are no specific management strategies for immune-related manifestations in people who live with CDG. However, there are some general management strategies that can be very helpful:
For infections:

  • Antibiotics/antivirals: Antibiotics are medicines that fight bacterial infections.
  • Intravenous administration of immunoglobulins which is a medical technique that delivers immunoglobulins (antibodies) directly into a person's vein (blood stream). These immunoglobulins help the body fight infections and may be considered if the infection is not responsive to antibiotic therapy. 

For other immune-related manifestations:

  • Intravenous immunoglobulin can also be recommended to you/your child, if you/your child have low immunoglobulin levels (hypogammaglobulinemia). 
  • If you/your child have low levels of some immune cells, your clinician can recommend that you take specific medicine that can help your body produce more immune cells (e.g., G-CSF for low neutrophil levels)
  • If you/your child have severe immune-related problems and you have been diagnosed with immunodeficiency, you should be followed by an immunologist (an immune system specialist). Your immunologist will then recommend the most appropriate treatment and management strategies for you.

Important Fact: Vaccines are extremely important and they do save lives! You/your child should be vaccinated unless your CDG specialist/clinical team advises you against it. You should know and be mindful that adverse reactions and non-response (i.e., that vaccines might not be effective) are possible. This is why you should keep an open communication line with your clinicians!
For further information on the immune system find a short-length resume here.

To better understand how immune-related manifestations may occur and be treated watch this video from Alila Medical Media: 

Keep in mind, you are not alone. Though Congenital Disorders of Glycosylation (CDG) are categorized as “rare” there is an amazing community at your fingertips working day and night to improve the lives of many people living with CDG and their family members. We want you to know everything that is available about therapies in lay language, but we suggest you enter into it at your own pace and comfort level.

The research to increase our current knowledge about immunological involvement in CDG has never been so full of promise!

Ensure that you are up to date, and join our mailing list:

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Susana Alves, Catarina Gomes (from Sci and Volunteer Program Nova School of Science and Technology 2021), and Rita Francisco and Vanessa Ferreira (CDG & Allies FCT, NOVA University, World CDG Organization and Portuguese Association for CDG)


Carlota Pascoal, Pedro Granjo and Ana Sofia Rodrigues (CDG & Allies FCT, NOVA University, World CDG Organization and Portuguese Association for CDG). Javier López and Kevin Aguirre (research volunteers at CDG & Allies FCT, NOVA University)

Content managers and peer reviewers

Marisa Godinho and Ana Verde (collaborators at CDG & Allies FCT, NOVA University). 


The Site cannot and does not contain medical or health advice. The information is provided for general informational and educational purposes only and is not a substitute for professional advice.

Accordingly, before taking any actions based upon such information, we encourage you to consult with the appropriate professionals. We do not provide any kind of medical or health advice. The use or reliance of any information contained on this site is solely at your own risk.

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Congenital Disorders of Glycosylation
Immune system
Antibodies vaccines
Innate immune response
Adaptive immune response

Page modified at Tuesday, October 11, 2022 - 11:21