Types of SCID | SCID Compass (2023)

Most types of SCID are considered typical SCID, characterized by low or no T cells and a non-functional immune system.

The exceptions to typical SCID are leaky SCID and Omenn Syndrome. Leaky SCID occurs when the defect in a gene allows for a normal, or even elevated, T cell count, which harms the immune system. Omenn Syndrome is characterized by defects in genes that cause high numbers of non-working T cells, and a lack of B cells resulting in a faulty immune system.

The treatment approach will vary with the SCID types so it’s important to know what kind of SCID is affecting the child.

Typical SCID

The most common types of typical SCID are: X-linked SCID, ADA SCID, RAG-1 or RAG-2 SCID, and IL7R SCID.

X-linked SCID is caused by mutations on the X chromosome, and generally only occurs in boys.

All of the other types of SCID are so-called autosomal recessive forms of SCID, meaning the mutations are on the other chromosomes. These forms of SCID can affect boys and girls. In autosomal recessive SCID, the child has two incorrect copies of the particular gene in each cell.

(Video) SCID Compass: Understanding SCID

Below is a list of all of the types of SCID, with the top four most common ones discussed first, and the remaining listed in alphabetical order

X-linked SCID

(T cell negative, B cell positive)

X-linked SCID is the most common form of SCID. Of all SCID cases, about 40% are X-linked. X-linked SCID generally only affects boys. Girls can be carriers of X-linked SCID but they won’t be affected.

X-linked SCID is caused by mutations in the IL2RG gene. The IL2RG gene tells the cells to make proteins that help immune cells to grow. Without these cells, the child with SCID will contract an infection quickly. X-linked SCID is characterized by very low T cells and non-functional B cells.

X-linked SCID is called X-linked SCID because the mutation of the gene is on the X chromosome. This means that much of the time, the disease is passed from mother to son. However, it can occur spontaneously; in other words, it can occur without the mother being a carrier.

A male with X-linked SCID will pass the gene along to his daughters, who will be carriers. He will not pass the gene to his sons. A female who is a carrier has a 50% chance of passing it along to daughters (who will then be carriers) and to sons (who will then have the disease).

Adenosine deaminase deficiency or ADA SCID

(T cell negative, B cell negative)

Adenosine Deaminase Deficiency, or ADA, SCID is the second most common type of SCID, accounting for about 15% of cases.

Normally, the ADA enzyme would eliminate a molecule called deoxyadenosine, generated when DNA is broken down. ADA converts deoxyadenosine, which is harmful, to a different molecule which is harmless.

When there is no ADA to convert the harmful deoxyadenosine, the deoxyadenosine builds up in the child’s system, and kills the immune system cells.

(Video) Update on SCID Compass

Lack of the ADA enzyme also leads to neurological problems such as cognitive impairment, hearing and visual impairment, low muscle tone, and movement disorders.

The neurological problems are not fully curable by hematopoietic stem cell transplantation, also known as a bone marrow transplant.

RAG-1 and RAG-2 deficiency SCID

(T cell negative, B cell negative)

Deficiencies in the RAG genes represent the third most common type of SCID. There can be mutations in either or both of the RAG-1 and RAG-2 genes.

The RAG-1 and RAG-2 deficiencies have also been found to cause Omenn Syndrome more often than other types of SCID. In Omenn Syndrome, abnormal T cells attack the body’s other cells.

IL7R deficiency SCID

(T cell negative, B cell positive)

The fourth most common type of SCID is IL7R (interleukin 7 receptor) deficiency. In this type of SCID, the defective gene prevents the creation of the IL7 receptor chain, which interrupts the signaling for the development of T cells. Children with the IL7R deficiency type of SCID have B cells but few or no T cells. Because of the lack of T cells, the B cells do not work.

Other Types ofSCID

CD3 complex component deficiency SCID

(T cell negative, B cell positive)

CD3 chain deficiency SCID comprises three other forms of SCID: CD3D, CD3E and CD247, also known as CD3Z. These forms of SCID are due to mutations in the genes that encode three of the individual protein chains that make up a part of the molecules on the surface of T cells. These molecules on the surface of the T cells are called the T cell receptor complex, or CD3. The CD3 chain deficiency results in damage to the T cells.

CD45 deficiency SCID

(T cell negative, B cell positive)

(Video) Welcome & Overview to SCID Compass

Another type of SCID is due to mutations in the gene encoding CD45, a protein found on the surface of all white cells that is necessary for T cell function.

Cernunnos-XLF deficiency SCID

(T cell negative, B cell negative)

Deficiency in the cernunnos-XLF gene is rare and is characterized by underdeveloped heads and brains, inability to grow at a normal rate, and lack of T and B cell function.

Coronin-1A deficiency SCID

(T cell negative, B cell positive)

Coronin-1A deficiency SCID causes a disruption of T cells produced by the thymus gland.

DCLRE1C or Artemis SCID or SCID A

(T cell negative, B cell negative)

Mutations in the DCLRE1C gene can cause Artemis SCID, also known as SCID A, and sometimes referred to as Athabascan-type SCID. This type of SCID is found primarily in the Navajo Nation. Mutations in the DCLRE1C gene can also cause Omenn Syndrome.

DNA ligase 4 deficiency SCID

(T cell negative, B cell negative)

This type of SCID is caused by a deficiency of DNA ligase 4 and it has a wide range of symptoms including underdeveloped heads and brains, a malformed face, failure to grow, and developmental delays, along with the lack of immune system.

DNA-PKcs deficiency SCID

(T cell negative, B cell negative)

(Video) SCID Compass: Exploring Treatment Options

DNA-PKcs deficiency SCID is extremely rare, and children with this disorder display the classic SCID symptoms including infections, diarrhea, and poor growth.

JAK3 deficiency SCID

(T cell negative, B cell positive)

JAK3 SCID is a deficiency in the Janus Kinase 3 gene. Because the protein made by the JAK3 gene works together with the protein made by the IL2RG gene, children with JAK3 deficient SCID have a similar lymphocyte profile characterized by low T cells. However, because the gene for JAK3 is not on the X chromosome this type of SCID can affect boys and girls.

LAT deficiency SCID

(T cell negative, B cell positive)

LAT deficiency SCID means that a child has mutations in the gene coding for linker for activation of T cells (or LAT), a molecule which plays a role in the development of T cells. LAT assists in helping T cells develop in the thymus.

Reticular dysgenesis SCID

(T cell negative, B cell negative)

Reticular dysgenesis is caused by mutations in the AK2 gene and is the most severe form of SCID. The reason why it is so severe is because not only is the child lacking in T and B cells but they are also lacking neutrophils which makes them even more susceptible to infection. Symptoms are present at birth include deafness, diarrhea, fever, sepsis, failure to thrive, infections, and abscesses.

Leaky SCID

Leaky SCID occurs when a person has symptoms similar to typical SCID, but with T cell counts that aren’t low enough to qualify as typical SCID. It’s called “leaky” because some T cells “leak” through and make a person’s blood cell count seem normal.

The T cell production doesn’t help the person fight infection, however. In leaky SCID, the T cells become over-activated and cause the body to attack itself. Leaky SCID can result in itchy skin, red skin, hair loss, enlarged liver and spleen, swollen lymph nodes, and diarrhea. It can also cause anemia and thyroid problems.

A person with leaky SCID might have a different type of gene mutation in the same gene as a person with typical SCID, such as RAG-1 and RAG-2 genes. Sometimes, children with leaky SCID don’t get diagnosed until they are older and even into adulthood.

(Video) SCID (Severe combined immunodeficiency) || symptoms and immunology || Immunodeficiency

Omenn Syndrome

Omenn Syndrome can present on its own or be caused by SCID. Genetic mutations that can cause Omenn Syndrome include RAG-1, RAG-2, adenosine deaminase deficiency (or ADA), Artemis and DNA ligase 4.

Omenn Syndrome infants suffer from a lack of an immune system as well as autoimmune activity in which the body attacks itself. Symptoms include red and peeling skin, hair loss, enlarged lymph nodes, enlarged liver and spleen.


What are the features of SCID? ›

Symptoms of SCID occur in infancy and include serious or life-threatening infections, especially viral infections, which may result in pneumonia and chronic diarrhea. Candida (yeast) infections of the mouth and diaper area and pneumonia caused by the fungus Pneumocystis jirovecii also are common.

How many cases of SCID are there? ›

Severe combined immunodeficiency (SCID) is very rare genetic disorder that causes life-threatening problems with the immune system. It is a type of primary immune deficiency. About 1 in 58,000 babies are born with SCID in the U.S. each year.

What is SCID X1? ›

X-linked severe combined immunodeficiency (SCID-X1) is an inherited disease caused by inactivating mutations in the gene encoding the interleukin 2 receptor common gamma chain (IL2RG), which is located on the X-chromosome.

What type of mutation causes SCID? ›

X-linked SCID results from a mutation in the interleukin 2 receptor gamma (IL2RG) gene which produces the common gamma chain subunit, a component of several IL receptors. IL2RG activates an important signalling molecule, JAK3. A mutation in JAK3, located on chromosome 19, can also result in SCID.

What are the 2 types of SCID? ›

There are several types of SCID. The type of SCID your baby has depends on which part of the immune system is problematic. The most common types of SCID are X-linked SCID and adenosine deaminase (ADA) deficiency. X-linked SCID occurs mostly in boys and is also called “bubble-boy” disease.

Which vector is used in SCID? ›

Lentiviral vectors are used today to treat SCID since they are very efficient at inserting the SCID gene of interest into the patient's stem cells. They are unlikely to cause serious problems such as leukemia.

Can girls have SCID? ›

Babies with this type of SCID will present with low or absent T and B cells, but typically have normal or high NK cells. RAG1 and RAG2 mutations are seen in 40% of those with leaky SCID and about 19% of those with SCID overall. Both boys and girls can be affected.

What is SCID caused by? ›

SCID is caused by genetic defects that affects the function of T cells. Depending on the type of SCID, B cells and NK cells can also be affected. These cells play important roles in helping the immune system battle bacteria, viruses and fungi that cause infections.

Who is most at risk for SCID? ›

Affected Populations

All types of SCID are very rare disorders that occur in approximately 1 or fewer births in 100,000 in the United States. SCID may be more common in people with Navajo, Apache, or Turkish ancestry.

How common is SCID x1? ›


X-linked SCID is a rare genetic disease (about 1 male in 75 000 live births) produced by a deficiency in T cells and natural killer (NK) cells associated with abnormal B cell function. Affected boys will die within a year if the T and NK deficiencies are not corrected.

What is a SCID panel? ›

This panel detects genetic causes of Severe Combined Immune Deficiency (SCID) and selected causes of Combined Immune Deficiency (CID) and CID with associated or syndromic features. Severe Combined Immunodeficiency is a genetically heterogeneous disorder of T lymphocyte development and adaptive immunity.

Is SCID and ADA the same? ›

Adenosine deaminase (ADA) deficiency is an inherited disorder that damages the immune system and causes severe combined immunodeficiency (SCID). People with SCID lack virtually all immune protection from bacteria, viruses, and fungi.

Why is SCID called bubble boy disease? ›

SCID is often called “bubble boy disease,” made known by the 1976 movie “The Boy in the Plastic Bubble.” Essentially, children with SCID lack the ability to produce an immune system. The human immune system constantly patrols, protects and defends the body from all types of “enemies,” including: bacteria.

How is SCID detected? ›

for SCID is done in all states in the United States. A blood spot from a needle prick on a baby's heel is used to screen for many different conditions. Newborn screening for SCID is done by looking for T cell receptor excision circles (or TRECs for short). TRECs are found in every healthy newborn's blood.

What are 3/4 causes of mutations? ›

Mutations are caused by environmental factors known as mutagens. Types of mutagens include radiation, chemicals, and infectious agents. Mutations may be spontaneous in nature.

Why are SCID mice used? ›

SCID mice, which virtually lack both T and B lymphocytes and accept xenogeneic cells, have been used during the last 5 years to provide a milieu for lymphocytes isolated from individuals with various autoimmune diseases, or for lymphocytes from mice that have a systemic lupus erythematosus-like syndrome.

What are the 4 types of viral vectors? ›

There are four main types of viral vectors (adeno-associated viral, adenoviral, lentiviral, retroviral) each with their own unique characteristics, uses, and limitations.

What are six types of vectors used in gene therapy? ›

Viral VectorGenetic MaterialHost Range
Adenovirus (all serotypes)dsDNABroad host range, infective for many cell types
RetrovirusRNABroad host range
LentivirusRNAEcotropic, amphotropic
Herpesviral vector (herpes simplex virus-1)dsDNABroad host range
1 more row
1 Mar 2020

What are the most common types of vectors? ›

The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes. Of these, the most commonly used vectors are plasmids.

How long do kids with SCID live? ›

Children who receive bone marrow transplants often lead healthy lives. If left untreated, babies with SCID can develop serious and fatal infections. Children with SCID who do not receive early treatment rarely live past two years of age.

At what age is SCID diagnosed? ›

Babies don't usually show signs of the disease until age four to six months,when the mother's antibodies wear off and the baby gets a serious infection.

What can cure SCID? ›

BMT, also known as a bone marrow transplant or blood stem cell transplant, is the only known cure for SCID. It replaces the unhealthy immune system with a healthy one. Allogeneic transplant is used for SCID.

How do you prevent SCID? ›

Can SCID be prevented in children? Since this disorder is inherited, parents of children with SCID should think about talking with a genetic counselor. The counselor can talk with you about genetic testing and family planning.

How is SCID treated today? ›

Most children with SCID are treated with hematopoietic stem cell transplantation, or HSCT, also known as a bone marrow transplantation. In this treatment, hematopoietic stem cells are taken from a donor. The hematopoietic stem cells that are taken from the donor are infused into a child with SCID.

Is SCID a disability? ›

Certain medical conditions qualified for quick review and approval from the Social Security Administration (SSA) for disability benefits. Severe Combined Immunodeficiency (SCID) in children is one of those conditions.

How much does SCID treatment cost? ›

Table I
Costs of treatment
Average cost per infant with SCID who die before definitive treatment$300 000
Average cost per infant with ADA SCID who do not undergo early HCT$450 000$200 000-$750 000
Average costs for infants with SCID who receive HCT as first-line therapy
23 more rows
11 Feb 2016

Can you live with Scids? ›

What are the survival rates for SCID? Without treatment, infants with SCID usually die from infections within the first two years of life. With an early bone marrow transplant, frequent follow-up and prompt treatment for infections, survival rates are very good.

How much does it cost to treat SCID? ›

Table 2
ParametersExpected ValuesSource
Cost ParametersUS$ (A$)
SCID Well treatment cost (per year)$34 ($50)[17]
SCID Moderate treatment cost (per year)$24,052 ($34,900)[17]
SCID Poor treatment cost (per year)$12,873 ($18,679)[17]
38 more rows
20 Jul 2022

What is the SCID-5 used for? ›

The SCID-5 is organized into diagnostic modules, and it assesses mood disorders, psychotic disorders, substance use disorders, anxiety disorders, obsessive–compulsive and related disorders, eating disorders, somatic symptom disorders, some sleep disorders (i.e., insomnia and hypersomnolence disorders), “externalizing ...

What is SCID II test? ›

The Structured Clinical Interview for DSM-IV (SCID-I/SCID-II; First, Gibbon, Spitzer, Williams, & Benjamin, 1997) is a semi-structured clinical interview administered by trained clinicians and designed to yield psychiatric diagnoses consistent with DSM-IV/DSM-IV-TR (American Psychiatric Association, 2000) diagnostic ...

What is the SCID-5 CT? ›

The SCID-5-CT is a version for clinical trials, which includes typical inclusion and exclusion criteria. The SCID-5-CV is a clinician version which is briefer and covers the diagnoses most often seen in clinical settings.

What are the 3 parts of ADA? ›

The ADA is divided into five titles:
  • Employment (Title I) ...
  • Public Services (Title II) ...
  • Public Accommodations (Title III) ...
  • Telecommunications (Title IV) ...
  • Miscellaneous (Title V)
26 Jul 2012

What gene therapy is used for SCID? ›

Ex vivo retrovirally mediated gene therapy has been shown within the last 20 yr to correct the T cell immunodeficiency caused by γc-deficiency (SCID X1) and adenosine deaminase (ADA) deficiency.

How long did bubble boy live? ›

Vetter became known as "The Bubble Boy" after he was placed in a germ-free plastic bubble that he lived in for 12 years. When he died at age 12 after an unsuccessful bone marrow transplant, public awareness of his condition waned.

What age is Bubble boy? ›

He died in 1984, at the age of 12.

How many states screen SCID? ›

As of December 2018, every state in the U.S., as well as Washington, DC and Puerto Rico, undertakes NBS for SCID for every child born, measuring a circular piece of DNA, the T cell receptor excision circle (TREC), using a small (1/8”) disc punched out of the DBS.

Do all states screen for SCID? ›

Nearly 4 million newborns are screened annually in the U.S. for numerous diseases, and 32 states and the District of Columbia currently screen for SCID.

What states test for SCID? ›

All 50 States Now Screening Newborns for Severe Combined Immunodeficiency (SCID)

What are 3 types of mutagens? ›

Mutagens can be physical mutagens, chemical mutagens, or biological mutagens. The ability of a substance to induce the alterations in the base pairs of DNA or mutation is known as mutagenicity.

What are the 3 types mutations? ›

Types of Mutations

There are three types of DNA Mutations: base substitutions, deletions and insertions.

What are 5 genetic diseases? ›

Genetic Disorders
  • Genetic Disorders. Sickle Cell Disease.
  • Cystic fibrosis. Cystic Fibrosis Liver Disease.
  • Brain, Nerves and Spine. Huntington's Disease.
  • Cleft lip and palate. Cleft Lip and Palate.

What are the symptoms of SCID in a child? ›

What are the symptoms of SCID in a child?
  • Pneumonia.
  • Repeated ear infections.
  • Meningitis.
  • Blood infection.
  • Chronic skin infections.
  • Yeast infections in the mouth and diaper area.
  • Diarrhea.
  • Liver infection (hepatitis)

What is the phenotype of SCID? ›

About 20% of patients with SCID have a phenotype characterized by an absence of mature T and B lymphocytes, while functional NK cells are detectable [3,4]. Usually the thymus is hypoplastic. The condition can be cured by allogeneic bone marrow transplantation.

How is SCID categorized? ›

Severe combined immunodeficiency (SCID) can be categorized as typical SCID or, if less severe, leaky SCID based upon the severity of T cell qualitative and quantitative deficiency. An overview of SCID, including clinical manifestations and diagnosis, is presented here.

How do you test for SCID? ›

A genetic test called full gene sequencing can be done to confirm a diagnosis of SCID. This test is performed on a sample of blood. It reads the instructions (DNA) that make up the genes known to cause SCID and can identify mutations in those genes.

What is the most severe form of SCID? ›

Reticular dysgenesis SCID

Reticular dysgenesis is caused by mutations in the AK2 gene and is the most severe form of SCID.

What are the 3 types of phenotypes? ›

With one locus and additive effects we have three phenotypic classes: AA, Aa and aa.

What are the four phenotypic classes? ›

The four phenotypic classes correspond to the genotypes: A_B_, A_bb, aaB_, and aabb. If either of the singly homozygous recessive genotypes (i.e. A_bb or aaB_) has the same phenotype as the double homozygous recessive (aabb), then a 9:3:4 phenotypic ratio will be obtained.

What are 3 examples of phenotype? ›

In humans, phenotype examples include earwax type, height, blood type, eye color, freckles, and hair color. And phenotypes aren't just physical traits. Behavior is also considered a phenotype.

What are the most common mutations in SCID? ›

The most common form of SCID, affecting nearly 30% of all cases, is due to a mutation in a gene on the X chromosome that encodes a component (or chain) called IL2RG shared by the T cell growth factor receptor and other growth factor receptors. This component is referred to as the common gamma chain (γc).

What is atypical SCID? ›

Leaky SCID (also known as Omenn syndrome or atypical SCID)

Leaky SCID is the clinical syndrome that occurs with severe itchy rashes, enlarged lymph nodes, spleen and liver and chronic diarrhea.


1. SCID Compass Lunch & Learn: May 13, 2021
(Immune Deficiency Foundation)
2. SCID Compass Lunch & Learn: March 10, 2021
(Immune Deficiency Foundation)
3. SCID Compass Lunch and Learn: PIDTC & IDF Neurodevelopmental Study
(Immune Deficiency Foundation)
4. SCID Compass: A Carrier's Perspective
(Immune Deficiency Foundation)
5. SCID Compass Lunch & Learn: June 23, 2020
(Immune Deficiency Foundation)
6. SCID Compass Lunch & Learn: December 16, 2020
(Immune Deficiency Foundation)
Top Articles
Latest Posts
Article information

Author: Manual Maggio

Last Updated: 12/27/2022

Views: 6371

Rating: 4.9 / 5 (49 voted)

Reviews: 88% of readers found this page helpful

Author information

Name: Manual Maggio

Birthday: 1998-01-20

Address: 359 Kelvin Stream, Lake Eldonview, MT 33517-1242

Phone: +577037762465

Job: Product Hospitality Supervisor

Hobby: Gardening, Web surfing, Video gaming, Amateur radio, Flag Football, Reading, Table tennis

Introduction: My name is Manual Maggio, I am a thankful, tender, adventurous, delightful, fantastic, proud, graceful person who loves writing and wants to share my knowledge and understanding with you.