🏷

Classifications

Harrison's Chapter

IUIS Category

👪

Inheritance

2

X-linked recessive inheritance HP:0001419

The most common form of SCID in Western populations, X-linked SCID, is caused by hemizygous IL2RG variants and is inherited in an X-linked recessive pattern.

X-linked recessive inheritance

Show evidence (1 reference)

PMID:20301584 SUPPORT Human Clinical

"The diagnosis of typical and atypical X-SCID is established in a male proband with suggestive findings and a hemizygous pathogenic variant in IL2RG identified by molecular genetic testing."

X-SCID is established by a hemizygous IL2RG variant in male probands, consistent with X-linked recessive inheritance.

Autosomal recessive inheritance HP:0000007

Most non-X-linked SCID subtypes (ADA, RAG1, RAG2, IL7R, JAK3, DCLRE1C/Artemis) are inherited in an autosomal recessive pattern, and these forms predominate in populations with high consanguinity.

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"The pattern of inheritance of SCID may be X-linked or autosomal recessive."

SCID is inherited as either X-linked or autosomal recessive, with the autosomal recessive forms covering ADA, RAG1/2, IL7R, JAK3, and Artemis deficiency.

◆

Subtypes

6

X-linked SCID (IL2RG deficiency, T-B+NK-)

IL2RG hgnc:6010

The most common form in Western populations (~50% of cases), caused by hemizygous loss-of-function variants in IL2RG encoding the common gamma chain. Immunophenotype is T-B+NK- (absent T and NK cells, present but non-functional B cells).

Adenosine deaminase deficiency (ADA-SCID, T-B-NK-)

ADA hgnc:186

A systemic purine metabolic disorder (~15% of SCID) in which deficiency of adenosine deaminase causes accumulation of toxic deoxyadenosine metabolites that are lymphotoxic, producing a T-B-NK- immunophenotype with absent humoral and cellular immunity.

RAG1/RAG2 deficiency (T-B-NK+)

RAG1 hgnc:9831 RAG2 hgnc:9832

Autosomal recessive SCID caused by defects in the recombination-activating genes RAG1 or RAG2, which block V(D)J recombination of antigen-receptor genes. Immunophenotype is T-B-NK+; hypomorphic alleles can cause Omenn syndrome. Most common form in consanguineous populations.

IL7R alpha-chain deficiency (T-B+NK+)

IL7R hgnc:6024

Autosomal recessive SCID caused by defects in the IL-7 receptor alpha chain, impairing IL-7 signaling required for T-cell development. Immunophenotype is T-B+NK+ (B and NK cells preserved).

JAK3 deficiency (T-B+NK-)

JAK3 hgnc:6193

Autosomal recessive SCID caused by defects in Janus kinase 3, the signaling kinase coupled to the common gamma chain. The immunophenotype (T-B+NK-) mirrors X-linked SCID because JAK3 acts immediately downstream of the gamma chain.

Artemis (DCLRE1C) deficiency (radiosensitive T-B-NK+)

DCLRE1C hgnc:17642

Autosomal recessive, radiosensitive SCID caused by defects in DCLRE1C/Artemis, a nuclease required for hairpin opening during V(D)J recombination and for non-homologous end-joining DNA repair. Immunophenotype is T-B-NK+ with increased cellular radiosensitivity.

⚙

Pathophysiology

5

Cytokine receptor signaling defect

In X-linked SCID, JAK3 deficiency, and IL7R deficiency, loss-of-function in the common gamma chain (IL2RG), its associated kinase JAK3, or the IL-7 receptor alpha chain abolishes IL-7-dependent JAK-STAT signaling that drives early thymocyte survival and proliferation, blocking T-cell development. IL2RG and JAK3 defects additionally abrogate NK-cell development (T-B+NK-), whereas IL7R defects spare B and NK cells (T-B+NK+).

thymocyte CL:0000893

IL2RG hgnc:6010 ↓ DECREASED

JAK-STAT cytokine receptor signaling GO:0007259 ↓ DECREASED

Downstream

Blocked T-lymphocyte development Loss of IL-7/JAK-STAT signaling halts thymocyte survival and proliferation, blocking maturation of T lymphocytes.

Show evidence (1 reference)

PMID:20301584 SUPPORT Human Clinical

"The diagnosis of typical and atypical X-SCID is established in a male proband with suggestive findings and a hemizygous pathogenic variant in IL2RG identified by molecular genetic testing."

IL2RG common gamma-chain loss underlies X-linked SCID, the cytokine-signaling form of disrupted T-cell development.

Defective V(D)J recombination and DNA repair

In RAG1, RAG2, and DCLRE1C (Artemis) deficiency, the machinery that assembles antigen-receptor genes is impaired. RAG1/RAG2 initiate site-specific DNA cleavage during V(D)J recombination, and Artemis opens the resulting DNA hairpins as part of non-homologous end-joining. Failure to recombine T-cell (and B-cell) receptor genes arrests lymphocyte development (T-B-NK+); Artemis loss additionally confers cellular radiosensitivity.

thymocyte CL:0000893

RAG1 hgnc:9831 ↓ DECREASED

V(D)J recombination GO:0033151 ↓ DECREASED DNA recombination GO:0006310 ↓ DECREASED

Downstream

Blocked T-lymphocyte development Failure of antigen-receptor gene recombination arrests thymocyte maturation, blocking T-cell development.

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Severe Combined Immunodeficiency (SCID) is an inherited group of rare, life-threatening disorders due to the defect in T cell development and function."

Defective V(D)J recombination (RAG1/RAG2/Artemis) is one of the inherited defects in T-cell development that causes SCID.

Toxic purine metabolite accumulation

In ADA deficiency, loss of adenosine deaminase activity causes accumulation of adenosine and especially deoxyadenosine (and intracellular dATP), which are lymphotoxic and impair lymphocyte development, viability, and function. The metabolic toxicity affects all lymphoid lineages, producing a T-B-NK- immunophenotype.

thymocyte CL:0000893

ADA hgnc:186 ↓ DECREASED

adenosine catabolic process GO:0006154 ↓ DECREASED

Downstream

Blocked T-lymphocyte development Lymphotoxic deoxyadenosine/dATP accumulation impairs thymocyte survival and blocks T-cell development.

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Adenosine deaminase (ADA) deficiency is a systemic purine metabolic disorder that primarily affects lymphocyte development, viability, and function."

ADA deficiency causes toxic purine-metabolite accumulation that impairs lymphocyte development, viability, and function.

Blocked T-lymphocyte development

The convergent consequence of all SCID subtypes is failure of hematopoietic stem cells to differentiate into mature, functional T lymphocytes in the thymus, yielding absent or severely reduced autologous T cells. Depending on the genetic lesion, B and/or NK lineages are also affected.

T cell CL:0000084 hematopoietic stem cell CL:0000037

T cell differentiation in thymus GO:0033077 ↓ DECREASED

Downstream

Absent adaptive immunity Absence of functional T lymphocytes abolishes cell-mediated immunity and (directly or via loss of T-cell help) humoral immunity.

Decreased total T cell count Blocked thymic T-cell development produces profound T lymphocytopenia.

Aplasia of the thymus Absence of developing thymocytes leaves a small, dysplastic thymus that yields an absent thymic shadow on imaging.

Decreased total B cell count In T-B- subtypes (RAG1/RAG2, Artemis, ADA) the same developmental/metabolic block also abolishes B-lymphocyte development.

Reduced total natural killer cell count In NK-negative subtypes (IL2RG, JAK3, ADA) the gamma-chain signaling or metabolic defect also abolishes NK-cell development.

Show evidence (1 reference)

PMID:36456361 SUPPORT Human Clinical

"Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes."

SCID converges on failed differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lineages affected by genotype.

Absent adaptive immunity

Without functional T cells (and often B cells), the patient cannot mount protective cellular or humoral adaptive immune responses, leaving the infant susceptible to overwhelming bacterial, viral, fungal, and protozoal infection.

T cell CL:0000084 B cell CL:0000236

adaptive immune response GO:0002250 ↓ DECREASED

Downstream

Severe combined immunodeficiency Loss of adaptive immunity is the defining clinical immunodeficiency.

Absent cellular immunity Loss of functional T cells abolishes cell-mediated immune responses.

Recurrent infections Without adaptive immunity, infants suffer recurrent and persistent infections from early infancy.

Recurrent fungal infections Loss of T-cell immunity predisposes to fungal infection including persistent candidiasis.

Chronic oral candidiasis Defective cellular immunity allows persistent oral Candida infection.

Pneumonia Loss of adaptive immunity predisposes to recurrent and opportunistic pneumonia (including Pneumocystis).

Chronic diarrhea Opportunistic enteric infection and immune dysfunction produce persistent diarrhea.

Failure to thrive Chronic infection and diarrhea cause poor linear growth and weight gain.

Hepatosplenomegaly Disseminated infection and immune dysregulation (e.g., Omenn syndrome) can produce hepatosplenomegaly.

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells) combined with the absence of both humoral and cellular immune function."

SCID produces absence of both humoral and cellular immune function, the loss of adaptive immunity.

⬡

Pathograph

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●

Phenotypes

13

Cardiovascular 2

Aplasia of the thymus Aplasia of the thymus HP:0005359

Show evidence (1 reference)

PMID:36456361 SUPPORT Human Clinical

"Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes"

Failure of thymic T-cell development underlies the small/aplastic thymus and absent thymic shadow seen in SCID.

Hepatosplenomegaly Hepatosplenomegaly HP:0001433

Show evidence (1 reference)

PMID:36456361 SUPPORT Human Clinical

"Omenn syndrome requires a generalized erythematous rash, absent transplacentally acquired maternal engraftment, and 2 or more of these: eosinophilia, elevated IgE, lymphadenopathy, hepatosplenomegaly."

Hepatosplenomegaly is a recognized feature of the Omenn syndrome presentation of leaky SCID (RAG hypomorphs).

Digestive 1

Chronic diarrhea FREQUENT Chronic diarrhea HP:0002028

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"poor linear growth and weight gain secondary to persistent diarrhea"

Persistent diarrhea is a frequent presenting feature contributing to failure to thrive in SCID.

Immune 2

Recurrent infections VERY_FREQUENT Recurrent infections HP:0002719

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Clinical manifestations are characterised by recurrent and severe bacterial, viral, and fungal opportunistic infections that start from early infancy period."

Recurrent severe opportunistic infections from early infancy are the cardinal clinical feature of SCID.

Pneumonia Pneumonia HP:0002090

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Untreated ADA-SCID presents as life-threatening opportunistic illnesses in the first weeks to months of life with poor linear growth and weight gain secondary to persistent diarrhea, extensive dermatitis, and recurrent pneumonia."

Recurrent pneumonia is a presenting opportunistic illness in untreated SCID.

Growth 1

Failure to thrive FREQUENT Failure to thrive HP:0001508

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Untreated ADA-SCID presents as life-threatening opportunistic illnesses in the first weeks to months of life with poor linear growth and weight gain secondary to persistent diarrhea"

Poor linear growth and weight gain (failure to thrive) follow chronic infection and diarrhea in untreated SCID.

Other 7

Severe combined immunodeficiency Severe combined immunodeficiency HP:0004430

Show evidence (1 reference)

PMID:36456361 SUPPORT Human Clinical

"Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes."

SCID is defined by combined defects of adaptive immunity arising from failed T-lymphocyte differentiation.

Absent cellular immunity Absent cellular immunity HP:0005354

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells) combined with the absence of both humoral and cellular immune function."

SCID features absence of cellular immune function.

Recurrent fungal infections Recurrent fungal infections HP:0002841

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Clinical manifestations are characterised by recurrent and severe bacterial, viral, and fungal opportunistic infections that start from early infancy period."

Recurrent fungal opportunistic infections are part of the SCID clinical picture.

Chronic oral candidiasis Chronic oral candidiasis HP:0009098

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Clinical manifestations are characterised by recurrent and severe bacterial, viral, and fungal opportunistic infections that start from early infancy period."

Persistent fungal (candidal) infection including oral thrush reflects the T-cell immune defect in SCID.

Decreased total T cell count VERY_FREQUENT Decreased total T cell count HP:0005403

Show evidence (1 reference)

PMID:36456361 SUPPORT Human Clinical

"Patients with typical SCID must have less than 0.05 × 109 autologous T cells/L on repetitive testing"

Typical SCID is defined by profoundly low autologous T-cell counts.

Decreased total B cell count Decreased total B cell count HP:0010976

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells)"

In T-B-NK- forms such as ADA-SCID, B-cell numbers are reduced along with T and NK cells.

Reduced total natural killer cell count Reduced total natural killer cell count HP:0040218

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells)"

NK-cell numbers are reduced in the NK-negative SCID immunophenotypes.

🧬

Genetic Associations

7

IL2RG (Causative)

Gene: IL2RG hgnc:6010

Show evidence (1 reference)

PMID:20301584 SUPPORT Human Clinical

"The diagnosis of typical and atypical X-SCID is established in a male proband with suggestive findings and a hemizygous pathogenic variant in IL2RG identified by molecular genetic testing."

A hemizygous IL2RG pathogenic variant establishes the diagnosis of X-linked SCID.

ADA (Causative)

Gene: ADA hgnc:186

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"Adenosine deaminase (ADA) deficiency is a systemic purine metabolic disorder that primarily affects lymphocyte development, viability, and function."

Biallelic ADA deficiency causes a systemic purine metabolic disorder affecting lymphocyte development, the basis of ADA-SCID.

RAG1 (Causative)

Gene: RAG1 hgnc:9831

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Deficiency of either RAG1 or RAG2 causes T-B-NK + SCID and is inherited in an autosomal recessive pattern."

RAG1 deficiency is a well-characterized autosomal recessive cause of T-B-NK+ SCID via a V(D)J-recombination defect.

RAG2 (Causative)

Gene: RAG2 hgnc:9832

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Deficiency of either RAG1 or RAG2 causes T-B-NK + SCID and is inherited in an autosomal recessive pattern."

RAG2 deficiency, like RAG1, abolishes V(D)J recombination and causes autosomal recessive T-B-NK+ SCID.

IL7R (Causative)

Gene: IL7R hgnc:6024

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Deficiency of ILR7 alpha causes T-B + NK + SCID, that accounts for around 10% of the total SCID patients."

IL7R (IL7R alpha) deficiency selectively impairs T-cell development, producing a T-B+NK+ form accounting for about 10% of SCID.

JAK3 (Causative)

Gene: JAK3 hgnc:6193

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"JAK3 deficiency constitutes around 6% of the total SCID patients and is inherited as an autosomal recessive trait."

JAK3 deficiency is an autosomal recessive SCID acting downstream of the common gamma chain, accounting for about 6% of cases.

DCLRE1C (Causative)

Gene: DCLRE1C hgnc:17642

Show evidence (1 reference)

PMID:33628209 SUPPORT Human Clinical

"RAG2 (17), JAK3 (15), DCLRE1C (13), IL7RA (9)"

A multi-institutional cohort identifies DCLRE1C (Artemis) defects as a recurrent molecular cause of SCID.

💊

Medical Actions

5

Hematopoietic stem cell transplantation

Action: hematopoietic stem cell transplantation MAXO:0000747

Allogeneic hematopoietic stem cell transplantation is the definitive curative treatment for SCID, reconstituting a functional immune system; outcomes are best when performed early, before the onset of infections.

Mechanism Target:

RESTORES Blocked T-lymphocyte development — Donor hematopoietic stem cells reconstitute thymic T-cell development and adaptive immunity.

Show evidence (1 reference)

PMID:32181275 SUPPORT Human Clinical

"Haematopoietic stem cell transplantation (HSCT) is the treatment of choice."

HSCT is the curative treatment of choice for SCID.

Hematopoietic stem cell gene therapy

Action: gene therapy MAXO:0001001

Autologous hematopoietic stem cell gene therapy corrects the causative gene in the patient's own stem cells; it is an established alternative to allogeneic HSCT for ADA-SCID (Strimvelis) and has shown clinical success for X-linked and other SCID forms.

Mechanism Target:

RESTORES Blocked T-lymphocyte development — Gene-corrected autologous stem cells restore lymphocyte development and adaptive immunity.

Show evidence (1 reference)

PMID:38355973 SUPPORT Human Clinical

"Long-term persistence of multilineage gene-corrected cells, metabolic detoxification, immune reconstitution and decreased infection rates were observed."

Retroviral hematopoietic stem cell gene therapy provides durable multilineage engraftment, immune reconstitution, and reduced infections in ADA-SCID.

Enzyme replacement therapy with pegademase (PEG-ADA)

Action: enzyme replacement or supplementation therapy MAXO:0000933

Agent: pegademase bovine NCIT:C77484

For ADA deficiency, enzyme replacement therapy with PEGylated adenosine deaminase corrects the metabolic defect, providing protection against infection; it is often used to stabilize patients before curative HSCT or gene therapy.

Mechanism Target:

INHIBITS Toxic purine metabolite accumulation — Exogenous PEGylated ADA clears toxic deoxyadenosine/adenosine, correcting the lymphotoxic metabolic defect.

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"enzyme replacement therapy (ERT) by intramuscular administration of PEGylated ADA"

Enzyme replacement therapy with PEGylated ADA is a targeted treatment correcting the ADA metabolic defect.

Immunoglobulin replacement therapy

Action: immunoglobulin infusion therapy MAXO:0001480

Intravenous (or subcutaneous) immunoglobulin replacement provides passive humoral protection while patients await or recover from definitive immune reconstitution.

Target Phenotypes: Recurrent infections HP:0002719

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"use of immunoglobulin infusions and antibiotics, particularly prophylaxis against Pneumocystis jirovecii pneumonia"

Immunoglobulin infusions are an explicit part of supportive management for the profound antibody deficiency seen in SCID.

Pneumocystis jirovecii pneumonia prophylaxis

Action: antimicrobial agent therapy MAXO:0001021

Antimicrobial prophylaxis, particularly against Pneumocystis jirovecii pneumonia, is a standard supportive measure to prevent opportunistic infection pending immune reconstitution.

Target Phenotypes: Pneumonia HP:0002090

Show evidence (1 reference)

PMID:20301656 SUPPORT Human Clinical

"particularly prophylaxis against Pneumocystis jirovecii pneumonia (formerly Pneumocystis carinii) and fungal infections"

Prophylaxis against Pneumocystis jirovecii pneumonia is a standard supportive measure in SCID.

{ }

Source YAML

click to show

name: Severe Combined Immunodeficiency
category: Mendelian
creation_date: "2026-06-22T00:00:00Z"
synonyms:
- SCID
- severe combined immunodeficiency disease
- bubble boy disease
description: >-
  Severe combined immunodeficiency (SCID) is a group of inborn errors of immunity
  characterized by profound defects in T-lymphocyte development and function, with
  variable effects on B and NK cells, that abrogate adaptive immunity. The shared
  final common pathway is failure of hematopoietic stem cells to differentiate into
  mature, functional T lymphocytes, producing absent cellular and (directly or
  indirectly) humoral immunity. Distinct molecular mechanisms define the major
  subtypes: defective cytokine receptor signaling (IL2RG, JAK3, IL7R), defective
  V(D)J recombination or DNA double-strand-break repair (RAG1, RAG2, DCLRE1C/Artemis),
  and toxic metabolite accumulation from purine-salvage enzyme deficiency (ADA).
  Affected infants present in the first months of life with recurrent and
  opportunistic infections, chronic diarrhea, failure to thrive, and absent thymic
  shadow, and the condition is fatal in infancy without immune reconstitution by
  hematopoietic stem cell transplantation, gene therapy, or (for ADA) enzyme
  replacement.
disease_term:
  preferred_term: severe combined immunodeficiency
  term:
    id: MONDO:0015974
    label: severe combined immunodeficiency
parents:
- combined immunodeficiency
- primary immunodeficiency
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:32181275
      reference_title: "Genetics of severe combined immunodeficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Severe Combined Immunodeficiency (SCID) is an inherited group of rare, life-threatening disorders due to the defect in T cell development and function."
      explanation: SCID is an inherited (genetic) disorder, placing it in Harrison's genetics-and-disease Part.
  iuis_category:
    classification_value: combined immunodeficiency
    evidence:
    - reference: PMID:36456361
      reference_title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Severe combined immunodeficiency (SCID) results from defects in the"
      explanation: SCID is the prototypic IUIS Table 1 immunodeficiency affecting cellular (and humoral) immunity.
inheritance:
- name: X-linked recessive inheritance
  description: >-
    The most common form of SCID in Western populations, X-linked SCID, is caused
    by hemizygous IL2RG variants and is inherited in an X-linked recessive pattern.
  inheritance_term:
    preferred_term: X-linked recessive inheritance
    term:
      id: HP:0001419
      label: X-linked recessive inheritance
  evidence:
  - reference: PMID:20301584
    reference_title: "X-Linked Severe Combined Immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of typical and atypical X-SCID is established in a male proband with suggestive findings and a hemizygous pathogenic variant in IL2RG identified by molecular genetic testing."
    explanation: X-SCID is established by a hemizygous IL2RG variant in male probands, consistent with X-linked recessive inheritance.
- name: Autosomal recessive inheritance
  description: >-
    Most non-X-linked SCID subtypes (ADA, RAG1, RAG2, IL7R, JAK3, DCLRE1C/Artemis)
    are inherited in an autosomal recessive pattern, and these forms predominate in
    populations with high consanguinity.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The pattern of inheritance of SCID may be X-linked or autosomal recessive."
    explanation: SCID is inherited as either X-linked or autosomal recessive, with the autosomal recessive forms covering ADA, RAG1/2, IL7R, JAK3, and Artemis deficiency.
has_subtypes:
- name: X-linked SCID
  display_name: X-linked SCID (IL2RG deficiency, T-B+NK-)
  description: >-
    The most common form in Western populations (~50% of cases), caused by
    hemizygous loss-of-function variants in IL2RG encoding the common gamma chain.
    Immunophenotype is T-B+NK- (absent T and NK cells, present but non-functional
    B cells).
  genes:
  - preferred_term: IL2RG
    term:
      id: hgnc:6010
      label: IL2RG
- name: ADA deficiency
  display_name: Adenosine deaminase deficiency (ADA-SCID, T-B-NK-)
  description: >-
    A systemic purine metabolic disorder (~15% of SCID) in which deficiency of
    adenosine deaminase causes accumulation of toxic deoxyadenosine metabolites
    that are lymphotoxic, producing a T-B-NK- immunophenotype with absent humoral
    and cellular immunity.
  genes:
  - preferred_term: ADA
    term:
      id: hgnc:186
      label: ADA
- name: RAG1/RAG2 deficiency
  display_name: RAG1/RAG2 deficiency (T-B-NK+)
  description: >-
    Autosomal recessive SCID caused by defects in the recombination-activating
    genes RAG1 or RAG2, which block V(D)J recombination of antigen-receptor genes.
    Immunophenotype is T-B-NK+; hypomorphic alleles can cause Omenn syndrome. Most
    common form in consanguineous populations.
  genes:
  - preferred_term: RAG1
    term:
      id: hgnc:9831
      label: RAG1
  - preferred_term: RAG2
    term:
      id: hgnc:9832
      label: RAG2
- name: IL7R deficiency
  display_name: IL7R alpha-chain deficiency (T-B+NK+)
  description: >-
    Autosomal recessive SCID caused by defects in the IL-7 receptor alpha chain,
    impairing IL-7 signaling required for T-cell development. Immunophenotype is
    T-B+NK+ (B and NK cells preserved).
  genes:
  - preferred_term: IL7R
    term:
      id: hgnc:6024
      label: IL7R
- name: JAK3 deficiency
  display_name: JAK3 deficiency (T-B+NK-)
  description: >-
    Autosomal recessive SCID caused by defects in Janus kinase 3, the signaling
    kinase coupled to the common gamma chain. The immunophenotype (T-B+NK-) mirrors
    X-linked SCID because JAK3 acts immediately downstream of the gamma chain.
  genes:
  - preferred_term: JAK3
    term:
      id: hgnc:6193
      label: JAK3
- name: Artemis deficiency
  display_name: Artemis (DCLRE1C) deficiency (radiosensitive T-B-NK+)
  description: >-
    Autosomal recessive, radiosensitive SCID caused by defects in DCLRE1C/Artemis,
    a nuclease required for hairpin opening during V(D)J recombination and for
    non-homologous end-joining DNA repair. Immunophenotype is T-B-NK+ with
    increased cellular radiosensitivity.
  genes:
  - preferred_term: DCLRE1C
    term:
      id: hgnc:17642
      label: DCLRE1C
genetic:
- name: IL2RG
  subtype: X-linked SCID
  gene_term:
    preferred_term: IL2RG
    term:
      id: hgnc:6010
      label: IL2RG
  association: Causative
  features: >-
    Hemizygous loss-of-function variants in IL2RG (common cytokine-receptor gamma
    chain) cause X-linked SCID, the most common SCID form in the US, Canada, and
    Europe (~50% of cases).
  evidence:
  - reference: PMID:20301584
    reference_title: "X-Linked Severe Combined Immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of typical and atypical X-SCID is established in a male proband with suggestive findings and a hemizygous pathogenic variant in IL2RG identified by molecular genetic testing."
    explanation: A hemizygous IL2RG pathogenic variant establishes the diagnosis of X-linked SCID.
- name: ADA
  subtype: ADA deficiency
  gene_term:
    preferred_term: ADA
    term:
      id: hgnc:186
      label: ADA
  association: Causative
  features: >-
    Biallelic ADA variants cause adenosine deaminase deficiency, a systemic purine
    metabolic disorder that primarily affects lymphocyte development, viability, and
    function, producing T-B-NK- SCID in about 80% of affected individuals.
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Adenosine deaminase (ADA) deficiency is a systemic purine metabolic disorder that primarily affects lymphocyte development, viability, and function."
    explanation: Biallelic ADA deficiency causes a systemic purine metabolic disorder affecting lymphocyte development, the basis of ADA-SCID.
- name: RAG1
  subtype: RAG1/RAG2 deficiency
  gene_term:
    preferred_term: RAG1
    term:
      id: hgnc:9831
      label: RAG1
  association: Causative
  features: >-
    Biallelic RAG1 variants impair V(D)J recombination, blocking T- and B-cell
    receptor assembly; RAG1 defects are among the most common autosomal recessive
    causes of SCID, especially in consanguineous populations.
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Deficiency of either RAG1 or RAG2 causes T-B-NK + SCID and is inherited in an autosomal recessive pattern."
    explanation: RAG1 deficiency is a well-characterized autosomal recessive cause of T-B-NK+ SCID via a V(D)J-recombination defect.
- name: RAG2
  subtype: RAG1/RAG2 deficiency
  gene_term:
    preferred_term: RAG2
    term:
      id: hgnc:9832
      label: RAG2
  association: Causative
  features: >-
    Biallelic RAG2 variants, like RAG1, abolish V(D)J recombination and cause
    T-B-NK+ SCID; hypomorphic RAG variants can produce Omenn syndrome.
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Deficiency of either RAG1 or RAG2 causes T-B-NK + SCID and is inherited in an autosomal recessive pattern."
    explanation: RAG2 deficiency, like RAG1, abolishes V(D)J recombination and causes autosomal recessive T-B-NK+ SCID.
- name: IL7R
  subtype: IL7R deficiency
  gene_term:
    preferred_term: IL7R
    term:
      id: hgnc:6024
      label: IL7R
  association: Causative
  features: >-
    Biallelic IL7R variants disrupt IL-7 receptor alpha-chain signaling required
    for T-cell development, producing T-B+NK+ SCID with preserved B and NK cells.
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Deficiency of ILR7 alpha causes T-B + NK + SCID, that accounts for around 10% of the total SCID patients."
    explanation: IL7R (IL7R alpha) deficiency selectively impairs T-cell development, producing a T-B+NK+ form accounting for about 10% of SCID.
- name: JAK3
  subtype: JAK3 deficiency
  gene_term:
    preferred_term: JAK3
    term:
      id: hgnc:6193
      label: JAK3
  association: Causative
  features: >-
    Biallelic JAK3 variants disrupt the Janus kinase coupled to the common gamma
    chain, producing a T-B+NK- immunophenotype that phenocopies X-linked SCID.
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "JAK3 deficiency constitutes around 6% of the total SCID patients and is inherited as an autosomal recessive trait."
    explanation: JAK3 deficiency is an autosomal recessive SCID acting downstream of the common gamma chain, accounting for about 6% of cases.
- name: DCLRE1C
  subtype: Artemis deficiency
  gene_term:
    preferred_term: DCLRE1C
    term:
      id: hgnc:17642
      label: DCLRE1C
  association: Causative
  features: >-
    Biallelic DCLRE1C (Artemis) variants impair hairpin opening during V(D)J
    recombination and non-homologous end-joining DNA repair, producing a
    radiosensitive T-B-NK+ SCID.
  evidence:
  - reference: PMID:33628209
    reference_title: "Clinical, Immunological, and Molecular Features of Severe Combined Immune Deficiency: A Multi-Institutional Experience From India."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "RAG2 (17), JAK3 (15), DCLRE1C (13), IL7RA (9)"
    explanation: A multi-institutional cohort identifies DCLRE1C (Artemis) defects as a recurrent molecular cause of SCID.
pathophysiology:
- name: Cytokine receptor signaling defect
  description: >-
    In X-linked SCID, JAK3 deficiency, and IL7R deficiency, loss-of-function in the
    common gamma chain (IL2RG), its associated kinase JAK3, or the IL-7 receptor
    alpha chain abolishes IL-7-dependent JAK-STAT signaling that drives early
    thymocyte survival and proliferation, blocking T-cell development. IL2RG and
    JAK3 defects additionally abrogate NK-cell development (T-B+NK-), whereas IL7R
    defects spare B and NK cells (T-B+NK+).
  gene:
    preferred_term: IL2RG
    modifier: DECREASED
    term:
      id: hgnc:6010
      label: IL2RG
  biological_processes:
  - preferred_term: JAK-STAT cytokine receptor signaling
    modifier: DECREASED
    term:
      id: GO:0007259
      label: cell surface receptor signaling pathway via JAK-STAT
  cell_types:
  - preferred_term: thymocyte
    term:
      id: CL:0000893
      label: thymocyte
  evidence:
  - reference: PMID:20301584
    reference_title: "X-Linked Severe Combined Immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of typical and atypical X-SCID is established in a male proband with suggestive findings and a hemizygous pathogenic variant in IL2RG identified by molecular genetic testing."
    explanation: IL2RG common gamma-chain loss underlies X-linked SCID, the cytokine-signaling form of disrupted T-cell development.
  downstream:
  - target: Blocked T-lymphocyte development
    description: Loss of IL-7/JAK-STAT signaling halts thymocyte survival and proliferation, blocking maturation of T lymphocytes.
    causal_link_type: DIRECT
- name: Defective V(D)J recombination and DNA repair
  description: >-
    In RAG1, RAG2, and DCLRE1C (Artemis) deficiency, the machinery that assembles
    antigen-receptor genes is impaired. RAG1/RAG2 initiate site-specific DNA cleavage
    during V(D)J recombination, and Artemis opens the resulting DNA hairpins as part
    of non-homologous end-joining. Failure to recombine T-cell (and B-cell) receptor
    genes arrests lymphocyte development (T-B-NK+); Artemis loss additionally confers
    cellular radiosensitivity.
  gene:
    preferred_term: RAG1
    modifier: DECREASED
    term:
      id: hgnc:9831
      label: RAG1
  biological_processes:
  - preferred_term: V(D)J recombination
    modifier: DECREASED
    term:
      id: GO:0033151
      label: V(D)J recombination
  - preferred_term: DNA recombination
    modifier: DECREASED
    term:
      id: GO:0006310
      label: DNA recombination
  cell_types:
  - preferred_term: thymocyte
    term:
      id: CL:0000893
      label: thymocyte
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Severe Combined Immunodeficiency (SCID) is an inherited group of rare, life-threatening disorders due to the defect in T cell development and function."
    explanation: Defective V(D)J recombination (RAG1/RAG2/Artemis) is one of the inherited defects in T-cell development that causes SCID.
  downstream:
  - target: Blocked T-lymphocyte development
    description: Failure of antigen-receptor gene recombination arrests thymocyte maturation, blocking T-cell development.
    causal_link_type: DIRECT
- name: Toxic purine metabolite accumulation
  description: >-
    In ADA deficiency, loss of adenosine deaminase activity causes accumulation of
    adenosine and especially deoxyadenosine (and intracellular dATP), which are
    lymphotoxic and impair lymphocyte development, viability, and function. The
    metabolic toxicity affects all lymphoid lineages, producing a T-B-NK-
    immunophenotype.
  gene:
    preferred_term: ADA
    modifier: DECREASED
    term:
      id: hgnc:186
      label: ADA
  biological_processes:
  - preferred_term: adenosine catabolic process
    modifier: DECREASED
    term:
      id: GO:0006154
      label: adenosine catabolic process
  chemical_entities:
  - preferred_term: 2'-deoxyadenosine
    modifier: INCREASED
    term:
      id: CHEBI:17256
      label: 2'-deoxyadenosine
  - preferred_term: adenosine
    modifier: INCREASED
    term:
      id: CHEBI:16335
      label: adenosine
  cell_types:
  - preferred_term: thymocyte
    term:
      id: CL:0000893
      label: thymocyte
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Adenosine deaminase (ADA) deficiency is a systemic purine metabolic disorder that primarily affects lymphocyte development, viability, and function."
    explanation: ADA deficiency causes toxic purine-metabolite accumulation that impairs lymphocyte development, viability, and function.
  downstream:
  - target: Blocked T-lymphocyte development
    description: Lymphotoxic deoxyadenosine/dATP accumulation impairs thymocyte survival and blocks T-cell development.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - deoxyadenosine and intracellular dATP accumulation; lymphocyte apoptosis
- name: Blocked T-lymphocyte development
  description: >-
    The convergent consequence of all SCID subtypes is failure of hematopoietic
    stem cells to differentiate into mature, functional T lymphocytes in the thymus,
    yielding absent or severely reduced autologous T cells. Depending on the genetic
    lesion, B and/or NK lineages are also affected.
  biological_processes:
  - preferred_term: T cell differentiation in thymus
    modifier: DECREASED
    term:
      id: GO:0033077
      label: T cell differentiation in thymus
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  - preferred_term: hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  evidence:
  - reference: PMID:36456361
    reference_title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes."
    explanation: SCID converges on failed differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lineages affected by genotype.
  downstream:
  - target: Absent adaptive immunity
    description: Absence of functional T lymphocytes abolishes cell-mediated immunity and (directly or via loss of T-cell help) humoral immunity.
    causal_link_type: DIRECT
  - target: Decreased total T cell count
    description: Blocked thymic T-cell development produces profound T lymphocytopenia.
    causal_link_type: DIRECT
  - target: Aplasia of the thymus
    description: Absence of developing thymocytes leaves a small, dysplastic thymus that yields an absent thymic shadow on imaging.
    causal_link_type: DIRECT
  - target: Decreased total B cell count
    description: In T-B- subtypes (RAG1/RAG2, Artemis, ADA) the same developmental/metabolic block also abolishes B-lymphocyte development.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - shared V(D)J recombination or metabolic block affecting the B-lymphoid lineage
  - target: Reduced total natural killer cell count
    description: In NK-negative subtypes (IL2RG, JAK3, ADA) the gamma-chain signaling or metabolic defect also abolishes NK-cell development.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - shared common gamma-chain signaling or metabolic defect affecting the NK lineage
- name: Absent adaptive immunity
  description: >-
    Without functional T cells (and often B cells), the patient cannot mount
    protective cellular or humoral adaptive immune responses, leaving the infant
    susceptible to overwhelming bacterial, viral, fungal, and protozoal infection.
  biological_processes:
  - preferred_term: adaptive immune response
    modifier: DECREASED
    term:
      id: GO:0002250
      label: adaptive immune response
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  - preferred_term: B cell
    term:
      id: CL:0000236
      label: B cell
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells) combined with the absence of both humoral and cellular immune function."
    explanation: SCID produces absence of both humoral and cellular immune function, the loss of adaptive immunity.
  downstream:
  - target: Severe combined immunodeficiency
    description: Loss of adaptive immunity is the defining clinical immunodeficiency.
    causal_link_type: DIRECT
  - target: Absent cellular immunity
    description: Loss of functional T cells abolishes cell-mediated immune responses.
    causal_link_type: DIRECT
  - target: Recurrent infections
    description: Without adaptive immunity, infants suffer recurrent and persistent infections from early infancy.
    causal_link_type: DIRECT
  - target: Recurrent fungal infections
    description: Loss of T-cell immunity predisposes to fungal infection including persistent candidiasis.
    causal_link_type: DIRECT
  - target: Chronic oral candidiasis
    description: Defective cellular immunity allows persistent oral Candida infection.
    causal_link_type: DIRECT
  - target: Pneumonia
    description: Loss of adaptive immunity predisposes to recurrent and opportunistic pneumonia (including Pneumocystis).
    causal_link_type: DIRECT
  - target: Chronic diarrhea
    description: Opportunistic enteric infection and immune dysfunction produce persistent diarrhea.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - opportunistic enteric and viral gastrointestinal infection
  - target: Failure to thrive
    description: Chronic infection and diarrhea cause poor linear growth and weight gain.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - chronic infection and persistent diarrhea with poor weight gain
  - target: Hepatosplenomegaly
    description: Disseminated infection and immune dysregulation (e.g., Omenn syndrome) can produce hepatosplenomegaly.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- category: Clinical
  name: Severe combined immunodeficiency
  description: Profound combined defect of cellular and humoral adaptive immunity is the defining feature.
  phenotype_term:
    preferred_term: Severe combined immunodeficiency
    term:
      id: HP:0004430
      label: Severe combined immunodeficiency
  evidence:
  - reference: PMID:36456361
    reference_title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes."
    explanation: SCID is defined by combined defects of adaptive immunity arising from failed T-lymphocyte differentiation.
- category: Clinical
  name: Absent cellular immunity
  description: Cell-mediated immune responses are absent owing to loss of functional T lymphocytes.
  phenotype_term:
    preferred_term: Absent cellular immunity
    term:
      id: HP:0005354
      label: Absent cellular immunity
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells) combined with the absence of both humoral and cellular immune function."
    explanation: SCID features absence of cellular immune function.
- category: Clinical
  name: Recurrent infections
  description: >-
    Recurrent, severe, and opportunistic bacterial, viral, fungal, and protozoal
    infections beginning in early infancy.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations are characterised by recurrent and severe bacterial, viral, and fungal opportunistic infections that start from early infancy period."
    explanation: Recurrent severe opportunistic infections from early infancy are the cardinal clinical feature of SCID.
- category: Clinical
  name: Pneumonia
  description: Recurrent and opportunistic pneumonia, including Pneumocystis jirovecii pneumonia, is common.
  phenotype_term:
    preferred_term: Pneumonia
    term:
      id: HP:0002090
      label: Pneumonia
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Untreated ADA-SCID presents as life-threatening opportunistic illnesses in the first weeks to months of life with poor linear growth and weight gain secondary to persistent diarrhea, extensive dermatitis, and recurrent pneumonia."
    explanation: Recurrent pneumonia is a presenting opportunistic illness in untreated SCID.
- category: Clinical
  name: Recurrent fungal infections
  description: Persistent fungal infection, especially mucocutaneous candidiasis, reflects loss of T-cell immunity.
  phenotype_term:
    preferred_term: Recurrent fungal infections
    term:
      id: HP:0002841
      label: Recurrent fungal infections
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations are characterised by recurrent and severe bacterial, viral, and fungal opportunistic infections that start from early infancy period."
    explanation: Recurrent fungal opportunistic infections are part of the SCID clinical picture.
- category: Clinical
  name: Chronic oral candidiasis
  description: Persistent oral thrush is a frequent early manifestation of defective cellular immunity.
  phenotype_term:
    preferred_term: Chronic oral candidiasis
    term:
      id: HP:0009098
      label: Chronic oral candidiasis
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations are characterised by recurrent and severe bacterial, viral, and fungal opportunistic infections that start from early infancy period."
    explanation: Persistent fungal (candidal) infection including oral thrush reflects the T-cell immune defect in SCID.
- category: Clinical
  name: Chronic diarrhea
  description: Persistent diarrhea, often from opportunistic enteric infection, is a common presenting feature.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Chronic diarrhea
    term:
      id: HP:0002028
      label: Chronic diarrhea
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "poor linear growth and weight gain secondary to persistent diarrhea"
    explanation: Persistent diarrhea is a frequent presenting feature contributing to failure to thrive in SCID.
- category: Clinical
  name: Failure to thrive
  description: Poor linear growth and weight gain secondary to chronic infection and persistent diarrhea.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Untreated ADA-SCID presents as life-threatening opportunistic illnesses in the first weeks to months of life with poor linear growth and weight gain secondary to persistent diarrhea"
    explanation: Poor linear growth and weight gain (failure to thrive) follow chronic infection and diarrhea in untreated SCID.
- category: Laboratory
  name: Decreased total T cell count
  description: Profound T lymphocytopenia (<0.05 x 10^9 autologous T cells/L in typical SCID).
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Decreased total T cell count
    term:
      id: HP:0005403
      label: Decreased total T cell count
  evidence:
  - reference: PMID:36456361
    reference_title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with typical SCID must have less than 0.05 × 109 autologous T cells/L on repetitive testing"
    explanation: Typical SCID is defined by profoundly low autologous T-cell counts.
- category: Laboratory
  name: Decreased total B cell count
  description: B lymphocytes are absent in T-B- forms (RAG1/RAG2, ADA, Artemis) and preserved in T-B+ forms.
  subtype: RAG1/RAG2 deficiency
  phenotype_term:
    preferred_term: Decreased total B cell count
    term:
      id: HP:0010976
      label: Decreased total B cell count
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells)"
    explanation: In T-B-NK- forms such as ADA-SCID, B-cell numbers are reduced along with T and NK cells.
- category: Laboratory
  name: Reduced total natural killer cell count
  description: NK cells are absent in T-B+NK- forms (IL2RG, JAK3) and in T-B-NK- ADA deficiency.
  subtype: X-linked SCID
  phenotype_term:
    preferred_term: Reduced total natural killer cell count
    term:
      id: HP:0040218
      label: Reduced total natural killer cell count
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Characteristic immune abnormalities are lymphocytopenia (low numbers of T, B, and NK cells)"
    explanation: NK-cell numbers are reduced in the NK-negative SCID immunophenotypes.
- category: Imaging
  name: Aplasia of the thymus
  description: A small, dysplastic thymus produces the characteristic absent thymic shadow on chest imaging.
  phenotype_term:
    preferred_term: Aplasia of the thymus
    term:
      id: HP:0005359
      label: Aplasia of the thymus
  evidence:
  - reference: PMID:36456361
    reference_title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes"
    explanation: Failure of thymic T-cell development underlies the small/aplastic thymus and absent thymic shadow seen in SCID.
- category: Clinical
  name: Hepatosplenomegaly
  description: Hepatosplenomegaly occurs particularly in Omenn syndrome and with disseminated infection.
  subtype: RAG1/RAG2 deficiency
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: PMID:36456361
    reference_title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Omenn syndrome requires a generalized erythematous rash, absent transplacentally acquired maternal engraftment, and 2 or more of these: eosinophilia, elevated IgE, lymphadenopathy, hepatosplenomegaly."
    explanation: Hepatosplenomegaly is a recognized feature of the Omenn syndrome presentation of leaky SCID (RAG hypomorphs).
treatments:
- name: Hematopoietic stem cell transplantation
  description: >-
    Allogeneic hematopoietic stem cell transplantation is the definitive curative
    treatment for SCID, reconstituting a functional immune system; outcomes are best
    when performed early, before the onset of infections.
  treatment_term:
    preferred_term: hematopoietic stem cell transplantation
    term:
      id: MAXO:0000747
      label: hematopoietic stem cell transplantation
  target_mechanisms:
  - target: Blocked T-lymphocyte development
    treatment_effect: RESTORES
    description: Donor hematopoietic stem cells reconstitute thymic T-cell development and adaptive immunity.
  evidence:
  - reference: PMID:32181275
    reference_title: "Genetics of severe combined immunodeficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Haematopoietic stem cell transplantation (HSCT) is the treatment of choice."
    explanation: HSCT is the curative treatment of choice for SCID.
- name: Hematopoietic stem cell gene therapy
  description: >-
    Autologous hematopoietic stem cell gene therapy corrects the causative gene in
    the patient's own stem cells; it is an established alternative to allogeneic HSCT
    for ADA-SCID (Strimvelis) and has shown clinical success for X-linked and other
    SCID forms.
  treatment_term:
    preferred_term: gene therapy
    term:
      id: MAXO:0001001
      label: gene therapy
  therapeutic_modality: GENE_THERAPY
  target_mechanisms:
  - target: Blocked T-lymphocyte development
    treatment_effect: RESTORES
    description: Gene-corrected autologous stem cells restore lymphocyte development and adaptive immunity.
  evidence:
  - reference: PMID:38355973
    reference_title: "Long-term and real-world safety and efficacy of retroviral gene therapy for adenosine deaminase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Long-term persistence of multilineage gene-corrected cells, metabolic detoxification, immune reconstitution and decreased infection rates were observed."
    explanation: Retroviral hematopoietic stem cell gene therapy provides durable multilineage engraftment, immune reconstitution, and reduced infections in ADA-SCID.
- name: Enzyme replacement therapy with pegademase (PEG-ADA)
  description: >-
    For ADA deficiency, enzyme replacement therapy with PEGylated adenosine
    deaminase corrects the metabolic defect, providing protection against infection;
    it is often used to stabilize patients before curative HSCT or gene therapy.
  treatment_term:
    preferred_term: enzyme replacement or supplementation therapy
    term:
      id: MAXO:0000933
      label: enzyme replacement or supplementation therapy
    therapeutic_agent:
    - preferred_term: pegademase bovine
      term:
        id: NCIT:C77484
        label: Pegademase Bovine
  target_mechanisms:
  - target: Toxic purine metabolite accumulation
    treatment_effect: INHIBITS
    description: Exogenous PEGylated ADA clears toxic deoxyadenosine/adenosine, correcting the lymphotoxic metabolic defect.
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "enzyme replacement therapy (ERT) by intramuscular administration of PEGylated ADA"
    explanation: Enzyme replacement therapy with PEGylated ADA is a targeted treatment correcting the ADA metabolic defect.
- name: Immunoglobulin replacement therapy
  description: >-
    Intravenous (or subcutaneous) immunoglobulin replacement provides passive humoral
    protection while patients await or recover from definitive immune reconstitution.
  treatment_term:
    preferred_term: immunoglobulin infusion therapy
    term:
      id: MAXO:0001480
      label: immunoglobulin infusion therapy
  target_phenotypes:
  - preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "use of immunoglobulin infusions and antibiotics, particularly prophylaxis against Pneumocystis jirovecii pneumonia"
    explanation: Immunoglobulin infusions are an explicit part of supportive management for the profound antibody deficiency seen in SCID.
- name: Pneumocystis jirovecii pneumonia prophylaxis
  description: >-
    Antimicrobial prophylaxis, particularly against Pneumocystis jirovecii pneumonia,
    is a standard supportive measure to prevent opportunistic infection pending
    immune reconstitution.
  treatment_term:
    preferred_term: antimicrobial agent therapy
    term:
      id: MAXO:0001021
      label: antimicrobial agent therapy
  target_phenotypes:
  - preferred_term: Pneumonia
    term:
      id: HP:0002090
      label: Pneumonia
  evidence:
  - reference: PMID:20301656
    reference_title: "Adenosine Deaminase Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "particularly prophylaxis against Pneumocystis jirovecii pneumonia (formerly Pneumocystis carinii) and fungal infections"
    explanation: Prophylaxis against Pneumocystis jirovecii pneumonia is a standard supportive measure in SCID.
prevalence:
- population: United States
  notes: >-
    Newborn-screening data indicate a SCID incidence of approximately 1 in 58,000
    live births in the United States.
  evidence:
  - reference: PMID:33551023
    reference_title: "SCID newborn screening: What we've learned."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "by 2019 all states in the United States had adopted versions of it in their public health programs"
    explanation: Universal TREC-based newborn screening, now adopted by all US states, defines population-level SCID detection.
notes: >-
  SCID is curated as a CURATE_ROOT_WITH_SUBTYPES entry: the root captures the shared
  final-common-pathway mechanism (gene defect -> blocked T-lymphocyte development ->
  absent adaptive immunity -> early life-threatening infection and failure to thrive),
  while has_subtypes records the major genetic forms grouped by mechanism class
  (cytokine signaling: IL2RG/JAK3/IL7R; V(D)J recombination/DNA repair: RAG1/RAG2/
  DCLRE1C; purine metabolism: ADA). Immunophenotypes follow the classic T/B/NK
  framework. Newborn screening uses the T-cell receptor excision circle (TREC) assay.
references:
- reference: PMID:20301584
  title: "X-Linked Severe Combined Immunodeficiency."
  tags:
  - GeneReviews
  findings: []
- reference: PMID:20301656
  title: "Adenosine Deaminase Deficiency."
  tags:
  - GeneReviews
  findings: []
- reference: PMID:32181275
  title: "Genetics of severe combined immunodeficiency."
  findings: []
- reference: PMID:36456361
  title: "The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions."
  findings: []
- reference: PMID:33628209
  title: "Clinical, Immunological, and Molecular Features of Severe Combined Immune Deficiency: A Multi-Institutional Experience From India."
  findings: []
- reference: PMID:33551023
  title: "SCID newborn screening: What we've learned."
  findings: []
- reference: PMID:38355973
  title: "Long-term and real-world safety and efficacy of retroviral gene therapy for adenosine deaminase deficiency."
  findings: []

📚

References & Deep Research

References

7

PMID:20301584

X-Linked Severe Combined Immunodeficiency.

No top-level findings curated for this source.

PMID:20301656

Adenosine Deaminase Deficiency.

No top-level findings curated for this source.

PMID:32181275

Genetics of severe combined immunodeficiency.

No top-level findings curated for this source.

PMID:36456361

The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions.

No top-level findings curated for this source.

PMID:33628209

Clinical, Immunological, and Molecular Features of Severe Combined Immune Deficiency: A Multi-Institutional Experience From India.

No top-level findings curated for this source.

PMID:33551023

SCID newborn screening: What we've learned.

No top-level findings curated for this source.

PMID:38355973

Long-term and real-world safety and efficacy of retroviral gene therapy for adenosine deaminase deficiency.

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

Disease Characteristics Research Template

Edison Scientific Literature 25 citations 2026-06-22T12:16:48.706243

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

Disease Name: Severe Combined Immunodeficiency
MONDO ID: (if available)
Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Severe Combined Immunodeficiency covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

What is the disease? Provide a concise overview.
What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
What are the common synonyms and alternative names?
Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
Risk Factors:

Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
Genetic risk factors (causal variants, susceptibility loci, modifier genes)
Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
Protective Factors:

Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases
Genetic protective factors (protective variants, modifier alleles)
Environmental protective factors (diet, lifestyle, exposures that reduce risk)
Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Pathogenic Variants:
Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
Variant type/class (missense, frameshift, nonsense, splice-site, structural)
Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
Functional consequences (loss of function, gain of function, dominant negative)
Modifier Genes: Genes that modify disease severity or expression
Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases
Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

Search first: CDC databases, WHO, PubMed, NHANES
Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

Search first: PubMed, Gene Ontology, Reactome
Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Molecular Profiling (if available):
Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
Advanced Technologies (if applicable):
Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

Organ Level:
Primary organs directly affected
Secondary organ involvement (complications, secondary effects)
Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Tissue and Cell Level:
Specific tissue types affected (epithelial, connective, muscle, nervous)
Specific cell populations targeted (with Cell Ontology terms)

Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Subcellular Level:
Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Localization:
Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

Onset:
Typical age of onset (congenital, pediatric, adult, geriatric)
Onset pattern (acute, subacute, chronic, insidious)

Search first: OMIM, Orphanet, HPO, PubMed
Progression:
Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
Progression rate (rapid, slow, variable)
Disease course pattern (episodic, relapsing-remitting, progressive, stable)
Disease duration (self-limited, chronic lifelong)

Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
Patterns:
Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

Epidemiology:
Prevalence (cases per 100,000 at given time)
Incidence (new cases per 100,000 per year)

Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries
For Genetic Etiology:
Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
Population Demographics:
Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
Geographic distribution of specific variants
Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

Clinical Tests:
Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
Genetic Testing:

Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen
Overview of recommended genetic testing approach
Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
FISH > Search first: ClinVar, cytogenetics databases, PubMed
Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
Omics-Based Diagnostics (if applicable):
RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
Clinical Criteria:
Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
Screening:
Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

Survival and Mortality:
Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
Morbidity and Function:
Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
Disease Course:
Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
Prediction:
Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

Pharmacotherapy:
Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
Advanced Therapeutics:
Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
Surgical and Interventional:
Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
Supportive and Rehabilitative:
Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
Experimental:
Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
Treatment Outcomes:
Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
Treatment Strategy:
Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

Prevention Levels:
Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
Immunization: Vaccine strategies (if applicable)

Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database
Screening and Early Detection:
Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
Behavioral Interventions: Lifestyle modifications to reduce risk

Search first: CDC, WHO, behavioral intervention databases, Cochrane Library
Counseling: Genetic counseling (risk assessment, family planning guidance)

Search first: NSGC resources, ACMG guidelines, GeneReviews
Public Health:
Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
Prophylaxis: Preventive medications or procedures

Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

Taxonomy: Species affected (with NCBI Taxon identifiers)

Search first: NCBI Taxonomy
Breed: Specific breeds affected (with VBO identifiers if applicable)

Search first: VBO (Vertebrate Breed Ontology)
Gene: Orthologous genes in other species (with NCBI Gene IDs)

Search first: NCBI Gene
Natural Disease:
Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
Comparative Biology:
Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
Transmission (if applicable):
Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

Model Types:
Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
Genetic Models:
Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
Model Characteristics:
Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
Applications:
Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
Resources:
Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

Cite primary literature (PMID preferred) for all mechanistic and clinical claims
Prioritize recent reviews and landmark papers
Include direct quotes from abstracts where possible to support key statements
Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

I apologize, but I'm unable to complete the comprehensive disease characteristics research report for Severe Combined Immunodeficiency (SCID) as requested. While I successfully retrieved relevant scientific literature covering SCID's clinical features, genetics, treatment approaches, newborn screening, and outcomes, I encountered technical difficulties with the evidence gathering system that prevented me from systematically extracting and organizing the detailed information needed for a comprehensive report across all 15 sections you specified.

From the papers I was able to access, I can provide the following preliminary overview based on the retrieved documents:

Disease Overview

Severe Combined Immunodeficiency (SCID) is a rare, life-threatening inherited immunodeficiency disorder characterized by profound defects in T lymphocyte development and function, often affecting both cellular and humoral immunity (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, dhomakonda2025areviewon pages 1-2, dvorak2023thediagnosisof pages 1-3). SCID is considered a pediatric emergency and, if left untreated, typically results in death within the first two years of life due to severe opportunistic infections (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, vignesh2021clinicalimmunologicaland pages 1-2).

Key Identifiers and Synonyms

SCID is also known as "bubble boy disease" or "living in the bubble" syndrome, named after the historical practice of isolating affected children in sterile environments (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2).

Epidemiology and Prevalence

Recent data from newborn screening programs indicate that SCID occurs with an incidence of approximately: - 1 in 58,000 live births (with a confidence interval of 1 in 46,000 to 1 in 80,000) in the United States based on newborn screening data across 11 states (currier2021scidnewbornscreening pages 1-2) - 1 in 103,240 for SCID in the Chinese population based on large-scale screening in Zhejiang Province, China (chen2024comprehensivenewbornscreening pages 1-2) - Earlier estimates had placed incidence at about 1 in 50,000 to 100,000 live births globally, though recent assessments based on newborn screening suggest higher rates (kumrah2020geneticsofsevere pages 1-2, vignesh2021clinicalimmunologicaland pages 2-3)

In countries with high consanguinity rates, incidence may be as high as 1 in 3,000 live births (vignesh2021clinicalimmunologicaland pages 2-3).

Genetic Basis and Causal Genes

SCID is caused by mutations in more than 20 different genes involved in lymphocyte development and function (vignesh2021clinicalimmunologicaland pages 2-3, kumrah2020geneticsofsevere pages 2-4). The major causal genes identified include:

X-linked SCID (most common in Western populations): - IL2RG (encoding the common gamma chain of IL-2 receptor) - accounts for approximately 50% of SCID cases in the US, Canada, and Europe (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, vignesh2021clinicalimmunologicaland pages 2-3)

Autosomal recessive forms (more common in populations with high consanguinity): - RAG1 and RAG2 (recombination activating genes) - most common in countries with high consanguinity rates (vignesh2021clinicalimmunologicaland pages 2-3, kumrah2020geneticsofsevere pages 2-4) - ADA (adenosine deaminase) - accounts for approximately 15% of all SCID cases (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2) - JAK3 (Janus kinase 3) - DCLRE1C (Artemis/DNA cross-link repair enzyme 1c) - IL7RA (IL-7 receptor alpha chain) - Other genes: NHEJ1, LIG4, PRKDC, CD3D, CD3E, CD3Z, PTPRC, AK2, PNP, and others (vignesh2021clinicalimmunologicaland pages 2-3, kumrah2020geneticsofsevere pages 2-4)

Clinical Manifestations and Phenotypes

Primary Symptoms:

Recurrent and severe opportunistic infections (bacterial, viral, fungal, and protozoal) beginning in early infancy (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, vignesh2021clinicalimmunologicaland pages 1-2)
Persistent oral thrush
Disseminated BCG infection (in countries with universal BCG vaccination)
Disseminated cytomegalovirus infection
Chronic diarrhea
Failure to thrive (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, vignesh2021clinicalimmunologicaland pages 1-2)

Age of Onset:

Symptoms typically present before 3 months of age (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2)
Median age of symptom onset: 2.5 months (interquartile range 1-5 months) based on Indian cohort (vignesh2021clinicalimmunologicaland pages 2-3)
Median age at diagnosis: 5 months (interquartile range 3.5-8 months) (vignesh2021clinicalimmunologicaland pages 2-3)

Classification:

SCID can be classified as: 1. Typical SCID: Characterized by gene mutations with severe infections, diarrhea, lack of T cells (<0.05 × 10⁹/L autologous T cells), reduction in naive T cells, and absence of proliferative responses to mitogens (dhomakonda2025areviewon pages 1-2, dvorak2023thediagnosisof pages 1-3) 2. Atypical/Leaky SCID: CD3+ > 300 cells/μL with diminished but detectable proliferative response to PHA (>10-30% of control) (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, dhomakonda2025areviewon pages 1-2) 3. Variant SCID: No known gene defect with 300-1500 T cells/L with reduced function (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, dhomakonda2025areviewon pages 1-2) 4. Omenn Syndrome: Characterized by generalized erythematous rash, elevated IgE, eosinophilia, hepatosplenomegaly, and lymphadenopathy (dvorak2023thediagnosisof pages 1-3, vignesh2021clinicalimmunologicaland pages 2-3)

Diagnostic Approaches

Newborn Screening:

T-cell receptor excision circle (TREC) testing from dried blood spots is now the standard newborn screening method for SCID (chen2024comprehensivenewbornscreening pages 1-2, currier2021scidnewbornscreening pages 1-2)
Universal newborn screening for SCID was added to the US Recommended Uniform Screening Panel in 2010, and by 2019 all US states had adopted TREC-based screening (currier2021scidnewbornscreening pages 1-2)
Multiplex real-time PCR can simultaneously detect TRECs, KRECs (kappa-deleting recombination excision circles for B-cell deficiencies), and other markers (chen2024comprehensivenewbornscreening pages 1-2)

Laboratory Testing:

Flow cytometry for lymphocyte subset analysis (CD3, CD4, CD8, CD19, CD56)
T-cell proliferation assays
Genetic testing via Sanger sequencing or next-generation sequencing (vignesh2021clinicalimmunologicaland pages 2-3)

Treatment Modalities

Hematopoietic Stem Cell Transplantation (HSCT):

HSCT is the definitive curative treatment for SCID (justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2, slatter2023personalizedhematopoieticstem pages 1-3)
Early diagnosis and transplantation before onset of infections dramatically improves outcomes (currier2021scidnewbornscreening pages 1-2, slatter2023personalizedhematopoieticstem pages 1-3)
Survival rates exceed 90% with matched sibling donors (slatter2023personalizedhematopoieticstem pages 1-3)
In the Indian cohort, only 8.3% (23/277) of patients received HSCT, with 11 survivors; mortality was recorded in 75.8% (210/277) of children, highlighting disparities in access to curative therapy (vignesh2021clinicalimmunologicaland pages 2-3)

Gene Therapy:

Autologous hematopoietic stem cell gene therapy has emerged as an alternative to allogeneic HSCT (kohn2023successesandchallenges pages 1-2, bruin2023advancesingene pages 1-2)
Gene therapy approaches include viral vector-mediated gene addition and gene editing with programmable nucleases (bruin2023advancesingene pages 1-2)
Long-term safety and efficacy have been demonstrated for ADA-SCID gene therapy, with market authorization granted in Europe (Strimvelis) (bruin2023advancesingene pages 1-2, migliavacca2024longtermandrealworld pages 1-2)
Gene therapy for X-SCID, Artemis SCID, and other forms has shown clinical success in trials (kohn2023successesandchallenges pages 1-2)
In one long-term study of 43 patients with ADA-SCID receiving retroviral gene therapy, all patients were alive at data cutoff with median follow-up of 5.0 years, and 2-year intervention-free survival was 88% (migliavacca2024longtermandrealworld pages 1-2)

Enzyme Replacement Therapy:

PEG-ADA (pegylated adenosine deaminase) for ADA-deficiency SCID
Can stabilize patients but provides limited long-term immune reconstitution (migliavacca2024longtermandrealworld pages 1-2)

Supportive Care:

Antimicrobial prophylaxis
Immunoglobulin replacement therapy
Strict isolation to prevent infections

Prognosis and Outcomes

Without Treatment:

Most children die before age 2 without bone marrow transplantation (dhomakonda2025areviewon pages 1-2)
Mortality rate of 75.8% was observed in an Indian cohort where most patients did not receive definitive treatment (vignesh2021clinicalimmunologicaland pages 2-3)

With Early Treatment:

Patients diagnosed through newborn screening and treated early have significantly better outcomes compared to those diagnosed after developing clinical symptoms (currier2021scidnewbornscreening pages 1-2, slatter2023personalizedhematopoieticstem pages 1-3)
Overall survival >90% after matched sibling/family donor HSCT (migliavacca2024longtermandrealworld pages 1-2)
Overall survival >85% after matched unrelated donor HSCT (improved over time) (migliavacca2024longtermandrealworld pages 1-2)

Animal Models

Immunodeficient Mouse Models:

Multiple immunodeficient mouse models have been developed to study SCID and test therapies: - SCID mice (Prkdc mutation) - deficient in T and B lymphocytes but retain NK cells (chen2022thedevelopmentand pages 1-2) - NOD/SCID mice - improved NK cell defects (chen2022thedevelopmentand pages 1-2) - NOD/SCID rg^null mice - lacking T, B, and NK cells, considered the gold standard for humanized mouse models (chen2022thedevelopmentand pages 1-2) - Rag1 and Rag2 knockout mice - lack mature T and B lymphocytes without spontaneous recovery (chen2022thedevelopmentand pages 1-2)

These models are used for xenograft studies, testing gene therapies, and understanding disease pathophysiology.

Limitations of this Response:

Due to technical difficulties with the evidence gathering system, I was unable to complete the comprehensive, fully-cited report across all 15 sections as specified in your template. A complete report would require:

Systematic extraction of specific molecular pathways, cellular processes, and biochemical mechanisms
Detailed ontology term mapping (HPO, GO, CL, UBERON, CHEBI, MAXO terms)
Comprehensive coverage of environmental factors, epigenetics, and metabolic profiling
Detailed therapeutic strategies with MAXO terms
Prevention strategies at all levels
Comparative biology and veterinary relevance
Complete model organism characterization

To provide you with the comprehensive disease knowledge base entry you need, I recommend re-running this analysis or accessing the retrieved papers directly for detailed extraction of the information outlined in sections you specifically require.

References

(justizvaillant2023severecombinedimmunodeficiency—classification pages 1-2): Angel A. Justiz-Vaillant, Darren Gopaul, Patrick Eberechi Akpaka, Sachin Soodeen, and Rodolfo Arozarena Fundora. Severe combined immunodeficiency—classification, microbiology association and treatment. Microorganisms, 11:1589, Jun 2023. URL: https://doi.org/10.3390/microorganisms11061589, doi:10.3390/microorganisms11061589. This article has 36 citations.
(dhomakonda2025areviewon pages 1-2): Bhavani Dhomakonda, Vankodoth Sireesha, Boddu Shirisha, Gadila Sushma, Mekala Sai Charitha, and T. Rama Rao. A review on types and treatment strategies of severe combined immunodeficiency. Journal of Drug Delivery and Therapeutics, 15:161-167, Mar 2025. URL: https://doi.org/10.22270/jddt.v15i3.7031, doi:10.22270/jddt.v15i3.7031. This article has 0 citations.
(dvorak2023thediagnosisof pages 1-3): Christopher C. Dvorak, Elie Haddad, Jennifer Heimall, Elizabeth Dunn, Rebecca H. Buckley, Donald B. Kohn, Morton J. Cowan, Sung-Yun Pai, Linda M. Griffith, Geoffrey D.E. Cuvelier, Hesham Eissa, Ami J. Shah, Richard J. O’Reilly, Michael A. Pulsipher, Nicola A.M. Wright, Roshini S. Abraham, Lisa Forbes Satter, Luigi D. Notarangelo, and Jennifer M. Puck. The diagnosis of severe combined immunodeficiency (scid): the primary immune deficiency treatment consortium (pidtc) 2022 definitions. Journal of Allergy and Clinical Immunology, 151:539-546, Feb 2023. URL: https://doi.org/10.1016/j.jaci.2022.10.022, doi:10.1016/j.jaci.2022.10.022. This article has 157 citations and is from a highest quality peer-reviewed journal.
(vignesh2021clinicalimmunologicaland pages 1-2): Pandiarajan Vignesh, Amit Rawat, Rajni Kumrah, Ankita Singh, Anjani Gummadi, Madhubala Sharma, Anit Kaur, Johnson Nameirakpam, Ankur Jindal, Deepti Suri, Anju Gupta, Alka Khadwal, Biman Saikia, Ranjana Walker Minz, Kaushal Sharma, Mukesh Desai, Prasad Taur, Vijaya Gowri, Ambreen Pandrowala, Aparna Dalvi, Neha Jodhawat, Priyanka Kambli, Manisha Rajan Madkaikar, Sagar Bhattad, Stalin Ramprakash, Raghuram CP, Ananthvikas Jayaram, Meena Sivasankaran, Deenadayalan Munirathnam, Sarath Balaji, Aruna Rajendran, Amita Aggarwal, Komal Singh, Fouzia Na, Biju George, Ankit Mehta, Harsha Prasada Lashkari, Ramya Uppuluri, Revathi Raj, Sandip Bartakke, Kirti Gupta, Sreejesh Sreedharanunni, Yumi Ogura, Tamaki Kato, Kohsuke Imai, Koon Wing Chan, Daniel Leung, Osamu Ohara, Shigeaki Nonoyama, Michael Hershfield, Yu-Lung Lau, and Surjit Singh. Clinical, immunological, and molecular features of severe combined immune deficiency: a multi-institutional experience from india. Frontiers in Immunology, Feb 2021. URL: https://doi.org/10.3389/fimmu.2020.619146, doi:10.3389/fimmu.2020.619146. This article has 62 citations and is from a peer-reviewed journal.
(currier2021scidnewbornscreening pages 1-2): Robert Currier and Jennifer M. Puck. Scid newborn screening: what we've learned. The Journal of allergy and clinical immunology, 147 2:417-426, Feb 2021. URL: https://doi.org/10.1016/j.jaci.2020.10.020, doi:10.1016/j.jaci.2020.10.020. This article has 138 citations.
(chen2024comprehensivenewbornscreening pages 1-2): Chi Chen, Chao Zhang, Ding-Wen Wu, Bing-Yi Wang, Rui Xiao, Xiao-Lei Huang, Xin Yang, Zhi-Gang Gao, and Ru-Lai Yang. Comprehensive newborn screening for severe combined immunodeficiency, x-linked agammaglobulinemia, and spinal muscular atrophy: the chinese experience. World Journal of Pediatrics, 20:1270-1282, Nov 2024. URL: https://doi.org/10.1007/s12519-024-00846-7, doi:10.1007/s12519-024-00846-7. This article has 12 citations and is from a peer-reviewed journal.
(kumrah2020geneticsofsevere pages 1-2): Rajni Kumrah, Pandiarajan Vignesh, Pratap Patra, Ankita Singh, Gummadi Anjani, Poonam Saini, Madhubala Sharma, Anit Kaur, and Amit Rawat. Genetics of severe combined immunodeficiency. Mar 2020. URL: https://doi.org/10.1016/j.gendis.2019.07.004, doi:10.1016/j.gendis.2019.07.004. This article has 88 citations.
(vignesh2021clinicalimmunologicaland pages 2-3): Pandiarajan Vignesh, Amit Rawat, Rajni Kumrah, Ankita Singh, Anjani Gummadi, Madhubala Sharma, Anit Kaur, Johnson Nameirakpam, Ankur Jindal, Deepti Suri, Anju Gupta, Alka Khadwal, Biman Saikia, Ranjana Walker Minz, Kaushal Sharma, Mukesh Desai, Prasad Taur, Vijaya Gowri, Ambreen Pandrowala, Aparna Dalvi, Neha Jodhawat, Priyanka Kambli, Manisha Rajan Madkaikar, Sagar Bhattad, Stalin Ramprakash, Raghuram CP, Ananthvikas Jayaram, Meena Sivasankaran, Deenadayalan Munirathnam, Sarath Balaji, Aruna Rajendran, Amita Aggarwal, Komal Singh, Fouzia Na, Biju George, Ankit Mehta, Harsha Prasada Lashkari, Ramya Uppuluri, Revathi Raj, Sandip Bartakke, Kirti Gupta, Sreejesh Sreedharanunni, Yumi Ogura, Tamaki Kato, Kohsuke Imai, Koon Wing Chan, Daniel Leung, Osamu Ohara, Shigeaki Nonoyama, Michael Hershfield, Yu-Lung Lau, and Surjit Singh. Clinical, immunological, and molecular features of severe combined immune deficiency: a multi-institutional experience from india. Frontiers in Immunology, Feb 2021. URL: https://doi.org/10.3389/fimmu.2020.619146, doi:10.3389/fimmu.2020.619146. This article has 62 citations and is from a peer-reviewed journal.
(kumrah2020geneticsofsevere pages 2-4): Rajni Kumrah, Pandiarajan Vignesh, Pratap Patra, Ankita Singh, Gummadi Anjani, Poonam Saini, Madhubala Sharma, Anit Kaur, and Amit Rawat. Genetics of severe combined immunodeficiency. Mar 2020. URL: https://doi.org/10.1016/j.gendis.2019.07.004, doi:10.1016/j.gendis.2019.07.004. This article has 88 citations.
(slatter2023personalizedhematopoieticstem pages 1-3): Mary Slatter and Su Han Lum. Personalized hematopoietic stem cell transplantation for inborn errors of immunity. Frontiers in Immunology, Apr 2023. URL: https://doi.org/10.3389/fimmu.2023.1162605, doi:10.3389/fimmu.2023.1162605. This article has 32 citations and is from a peer-reviewed journal.
(kohn2023successesandchallenges pages 1-2): Donald B. Kohn, Yvonne Y. Chen, and Melissa J. Spencer. Successes and challenges in clinical gene therapy. Gene Therapy, 30:738-746, Nov 2023. URL: https://doi.org/10.1038/s41434-023-00390-5, doi:10.1038/s41434-023-00390-5. This article has 228 citations and is from a peer-reviewed journal.
(bruin2023advancesingene pages 1-2): Lisa M. Ott de Bruin, Arjan C. Lankester, and Frank J.T. Staal. Advances in gene therapy for inborn errors of immunity. Current Opinion in Allergy and Clinical Immunology, 23:467-477, Oct 2023. URL: https://doi.org/10.1097/aci.0000000000000952, doi:10.1097/aci.0000000000000952. This article has 32 citations and is from a peer-reviewed journal.
(migliavacca2024longtermandrealworld pages 1-2): Maddalena Migliavacca, Federica Barzaghi, Claudia Fossati, Paola M. V. Rancoita, Michela Gabaldo, Francesca Dionisio, Stefania Giannelli, Federica Andrea Salerio, Francesca Ferrua, Francesca Tucci, Valeria Calbi, Vera Gallo, Salvatore Recupero, Giulia Consiglieri, Roberta Pajno, Maria Sambuco, Alessio Priolo, Chiara Ferri, Vittoria Garella, Ilaria Monti, Paolo Silvani, Silvia Darin, Miriam Casiraghi, Ambra Corti, Stefano Zancan, Margherita Levi, Daniela Cesana, Filippo Carlucci, Anna Pituch-Noworolska, Dalia AbdElaziz, Ulrich Baumann, Andrea Finocchi, Caterina Cancrini, Saverio Ladogana, Andrea Meinhardt, Isabelle Meyts, Davide Montin, Lucia Dora Notarangelo, Fulvio Porta, Marlène Pasquet, Carsten Speckmann, Polina Stepensky, Alberto Tommasini, Marco Rabusin, Zeynep Karakas, Miguel Galicchio, Lucia Leonardi, Marzia Duse, Sukru Nail Guner, Clelia Di Serio, Fabio Ciceri, Maria Ester Bernardo, Alessandro Aiuti, and Maria Pia Cicalese. Long-term and real-world safety and efficacy of retroviral gene therapy for adenosine deaminase deficiency. Nature medicine, 30:488-497, Feb 2024. URL: https://doi.org/10.1038/s41591-023-02789-4, doi:10.1038/s41591-023-02789-4. This article has 31 citations and is from a highest quality peer-reviewed journal.
(chen2022thedevelopmentand pages 1-2): Jiaxuan Chen, Shuzhen Liao, Zengzhi Xiao, Quanren Pan, Xi Wang, Kangyuan Shen, Shuting Wang, Lawei Yang, Fengbiao Guo, Hua-feng Liu, and Qingjun Pan. The development and improvement of immunodeficient mice and humanized immune system mouse models. Frontiers in Immunology, Oct 2022. URL: https://doi.org/10.3389/fimmu.2022.1007579, doi:10.3389/fimmu.2022.1007579. This article has 224 citations and is from a peer-reviewed journal.

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Newborn Screening:

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Hematopoietic Stem Cell Transplantation (HSCT):

Gene Therapy:

Enzyme Replacement Therapy:

Supportive Care:

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Without Treatment:

With Early Treatment:

Animal Models

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