What is the cause of SCID?

What Is SCID? A Guide to Immune Deficiency in Infants

Severe Combined Immune Deficiency (SCID) is a serious primary immunodeficiency disorder characterised by the lack of both T-cell and B-cell functions. More than 20 genetic mutations have been found to be potentially responsible for SCID. Though the exact aetiology, laboratory findings, and mode of inheritance vary with the type, infants with classical SCID have extreme dysfunction of both T cell and B cell function. As the treatment varies based on the type of SCID, one needs to be aware of the particular form for proper handling.

Read on to find out more!

What is Severe Combined Immunodeficiency (SCID)?

SCID is a rare illness in which newborn babies are born with a significantly compromised or even non-working immune system. SCID is a form of primary immunodeficiency that weakens the immune system, making it unable to function properly. Individuals with SCID are highly vulnerable to infections, including everyday illnesses that are typically mild in others. SCID is usually lethal before the age of two without treatment.

What are the various types of SCID?

The immune system is the defence system of the body, which recognises destructive invaders like viruses, bacteria, fungi, protozoa, or toxins and engages white blood cells called lymphocytes to fight them. The principal types of lymphocytes are

• T cells
• B cells
• Natural killer (NK) cells
   

The majority of SCID is observed in infants who do not have T cells, which are vital for maintaining B cell function. Such children also lack the immune responses that B cells typically provide. The term "combined" in SCID reflects this dual deficiency of both T and B cells. SCID manifests in several forms, each associated with the absence of specific immune cells, but all forms are equally severe. Healthcare providers will diagnose and specify the exact type of SCID affecting the child to guide treatment.

What Are The Symptoms of SCID?

SCID might not always show obvious symptoms early on. However, when symptoms do appear, they often include:

• Failed weight gain or expected growth.
• Chronic diarrhoea.
• Severe and chronic infections.
   

An SCID child's immune system is significantly weakened and much more vulnerable to illness. Infections tend to be more intense and more challenging to treat compared to healthy children.

Children with SCID are prone to all types of infections, such as

• Infections caused by bacteria
• Infections caused by viruses
• Infections caused by fungi
• Parasitic infections
   

These infections may be more common in infants with a condition of SCID, such as:

• Diaper rash or thrush caused by yeast infection
• Chickenpox
• Cold sores caused by the herpes simplex virus
• Ear infections
• Pneumonia
• Meningitis
   

What Are The Various Causes of SCID?

SCID is a genetic disease due to gene mutations. Scientists have discovered multiple genetic mutations responsible for causing the condition. These mutations in the genes are inherited through parents and may occur in various patterns.

Some SCIDs are autosomal recessive, whereby both parents carry the faulty gene and pass it to their offspring. Others are X-linked due to a mutation in the X chromosome. Males, having just one X chromosome, are at greater risk for X-linked SCID, but females, having two X's, are usually carriers.

What is the treatment for SCID?

A stem cell or bone marrow transplant is essential for treating a newborn diagnosed with SCID. This involves replacing your faulty stem cells with healthy ones donated by someone else. These new stem cells will restore your child's immune system, and their body will learn to fight infection.

The ideal donors are healthy biological siblings who themselves don't have SCID. If you do not have a compatible sibling donor, medical teams will search stem cell registries—publicly maintained lists of donated stem cells that might be able to match your child.

While your child waits for the stem cell transplant, they may also need other treatments, including:

• Antibiotics
• Antivirals
• Antifungals
• IVIG (intravenous immunoglobulin) infusions
• Gene therapy
   

These therapies suppress infections temporarily but are not therapeutic for SCID. The only way to guarantee an effective cure is successful stem cell transplantation.

Your child may also need to remain in a sterile isolation room during this time. This involves being treated in a totally germ-free environment where anything that enters the room is sterilised to avoid infection. SCID is also referred to as "bubble baby disease" due to the requirement of isolation, but this is incorrect medically and offensive.

How Long Can a Person with SCID Expect to Live?

If left untreated for SCID, babies usually do not live beyond their first or second year of life. Children who received a successful stem cell transplant, on the other hand, typically have a relatively typical lifespan. With a fully restored immune system, they usually prevent the development of long-term complications.

Finding out that your child has SCID is overwhelming, as if the air has been sucked out of the room. Feel free to speak with your doctors about any doubts or concerns you may have.

It is also recommended to take health insurance to cover your health and finances during crucial moments. At Star Health, we offer comprehensive coverage for various health conditions under our general insurance plans. We also provide hassle-free, cashless claim settlements with reduced turnaround time across over 14,000 network hospitals in India.