Combined immunodeficiencies (D81)
ICD-10 code section D81 covers combined immunodeficiencies, a group of rare disorders where both T-cell and B-cell immunity are impaired. These conditions include various forms of severe combined immunodeficiency (SCID), enzyme deficiencies, and other inherited immune system failures.
The ICD-10 code for combined immunodeficiencies encompasses multiple subtypes. For example, D81.0 refers to SCID with reticular dysgenesis, associated with absent T cell maturation. Codes such as D81.1 and D81.2 describe SCID variants characterized by differing T- and B-cell counts, including cases caused by genetic defects affecting IL-2 receptors or recombination-activating genes (RAG). D81.3 relates to adenosine deaminase (ADA) deficiency, a key enzyme defect causing immunodeficiency. Other codes, such as D81.4 for Nezelof's syndrome and D81.5 for purine nucleoside phosphorylase deficiency, identify specific combined immune disorders. The section also includes rarer forms like major histocompatibility complex class I and II deficiencies (D81.6, D81.7) and biotin-dependent carboxylase deficiencies (D81.81). Unspecified or other forms are coded under D81.8 and D81.9. Knowing these codes helps accurately capture diagnoses like SCID, hereditary eosinophilia, or combined immunodeficiency syndromes for clinical and billing purposes.
Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50–D89)
Certain disorders involving the immune mechanism (D80-D89)
D81 Combined immunodeficiencies
- D81.0 Severe combined immunodeficiency [SCID] with reticular dysgenesis
- D81.1 Severe combined immunodeficiency [SCID] with low T- and B-cell numbers
- D81.2 Severe combined immunodeficiency [SCID] with low or normal B-cell numbers
D81.3 Adenosine deaminase [ADA] deficiency
- D81.30 Adenosine deaminase deficiency, unspecified
- D81.31 Severe combined immunodeficiency due to adenosine deaminase deficiency
- D81.32 Adenosine deaminase 2 deficiency
- D81.39 Other adenosine deaminase deficiency
- D81.4 Nezelof's syndrome
- D81.5 Purine nucleoside phosphorylase [PNP] deficiency
- D81.6 Major histocompatibility complex class I deficiency
- D81.7 Major histocompatibility complex class II deficiency
D81.8 Other combined immunodeficiencies
D81.81 Biotin-dependent carboxylase deficiency
- D81.810 Biotinidase deficiency
- D81.818 Other biotin-dependent carboxylase deficiency
- D81.819 Biotin-dependent carboxylase deficiency, unspecified
- D81.82 Activated Phosphoinositide 3-kinase Delta Syndrome [APDS]
- D81.89 Other combined immunodeficiencies
- D81.9 Combined immunodeficiency, unspecified
Combined immunodeficiencies (D81)
Instructional Notations
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- autosomal recessive agammaglobulinemia Swiss type D80.0
Clinical Terms
The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.
Biotinidase Deficiency
The late onset form of MULTIPLE CARBOXYLASE DEFICIENCY (deficiency of the activities of biotin-dependent enzymes propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and PYRUVATE CARBOXYLASE) due to a defect or deficiency in biotinidase which is essential for recycling BIOTIN.
DNA
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
DNA End-Joining Repair
The repair of DOUBLE-STRAND DNA BREAKS by rejoining the broken ends of DNA to each other directly.
DNA Repair
The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.
DNA Repair Enzymes
Enzymes that are involved in the reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule, which contained damaged regions.
DNA Repair-Deficiency Disorders
Disorders resulting from defective DNA REPAIR processes or the associated cellular responses to DNA DAMAGE.
Holocarboxylase Synthetase Deficiency
The neonatal form of MULTIPLE CARBOXYLASE DEFICIENCY that is caused by a defect or deficiency in holocarboxylase synthetase. HLCS is the enzyme that covalently links biotin to the biotin dependent carboxylases (propionyl-CoA-carboxylase, pyruvate carboxylase, and beta-methylcrotonyl-CoA carboxylase).
Multiple Carboxylase Deficiency
A deficiency in the activities of biotin-dependent enzymes (propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and PYRUVATE CARBOXYLASE) due to one of two defects in BIOTIN metabolism. The neonatal form is due to HOLOCARBOXYLASE SYNTHETASE DEFICIENCY. The late-onset form is due to BIOTINIDASE DEFICIENCY.
O(6)-Methylguanine-DNA Methyltransferase
An enzyme that transfers methyl groups from O(6)-methylguanine, and other methylated moieties of DNA, to a cysteine residue in itself, thus repairing alkylated DNA in a single-step reaction. EC 2.1.1.63.
Rad52 DNA Repair and Recombination Protein
A DNA-binding protein that mediates DNA REPAIR of double strand breaks, and HOMOLOGOUS RECOMBINATION.
Recombinational DNA Repair
Repair of DNA DAMAGE by exchange of DNA between matching sequences, usually between the allelic DNA (ALLELES) of sister chromatids.
