|
| 1 | +name: Atopic Dermatitis |
| 2 | +category: Complex |
| 3 | +parents: |
| 4 | +- Dermatological Disease |
| 5 | +- Chronic Inflammatory Disease |
| 6 | +- Allergic Disease |
| 7 | +has_subtypes: |
| 8 | +- name: Early-Onset Atopic Dermatitis |
| 9 | + description: Onset in infancy or early childhood, often associated with the |
| 10 | + atopic march progressing to asthma and allergic rhinitis. |
| 11 | +- name: Adult-Onset Atopic Dermatitis |
| 12 | + description: First presentation in adulthood, often with different clinical |
| 13 | + distribution and associations compared to childhood-onset disease. |
| 14 | +- name: Extrinsic Atopic Dermatitis |
| 15 | + description: Associated with IgE-mediated sensitization to environmental |
| 16 | + allergens. Elevated serum IgE and positive skin prick tests. |
| 17 | +- name: Intrinsic Atopic Dermatitis |
| 18 | + description: Without IgE-mediated sensitization. Normal serum IgE levels. |
| 19 | + Represents approximately 20% of cases. |
| 20 | +pathophysiology: |
| 21 | +- name: Epidermal Barrier Dysfunction |
| 22 | + description: Loss-of-function mutations in filaggrin (FLG) and other barrier |
| 23 | + proteins lead to impaired skin barrier integrity, increased transepidermal |
| 24 | + water loss, and enhanced allergen penetration. This is the primary |
| 25 | + initiating event in many patients. |
| 26 | + genes: |
| 27 | + - preferred_term: FLG |
| 28 | + term: |
| 29 | + id: hgnc:3748 |
| 30 | + label: FLG |
| 31 | + biological_processes: |
| 32 | + - preferred_term: Keratinization |
| 33 | + term: |
| 34 | + id: GO:0031424 |
| 35 | + label: keratinization |
| 36 | + cell_types: |
| 37 | + - preferred_term: Keratinocyte |
| 38 | + term: |
| 39 | + id: CL:0000312 |
| 40 | + label: keratinocyte |
| 41 | + evidence: |
| 42 | + - reference: PMID:16550169 |
| 43 | + supports: SUPPORT |
| 44 | + evidence_source: HUMAN_CLINICAL |
| 45 | + snippet: Filaggrin is a key protein that facilitates terminal |
| 46 | + differentiation of the epidermis and formation of the skin barrier. Here |
| 47 | + we show that two independent loss-of-function genetic variants (R510X |
| 48 | + [sic, correct designation is R501X] and 2282del4) in the gene encoding |
| 49 | + filaggrin (FLG) are very strong predisposing factors for atopic |
| 50 | + dermatitis. |
| 51 | + explanation: Landmark study establishing FLG loss-of-function as the |
| 52 | + strongest genetic risk factor for atopic dermatitis, with ~9% carrier |
| 53 | + frequency in Europeans. |
| 54 | + - reference: PMID:21388665 |
| 55 | + supports: PARTIAL |
| 56 | + evidence_source: HUMAN_CLINICAL |
| 57 | + snippet: They are similar in that they are complex inherited diseases |
| 58 | + involving genes that encode immune components and structural proteins that |
| 59 | + regulate differentiation of epidermal cells. Each disease is characterized |
| 60 | + by proliferation of epidermal keratinocytes and abnormal cornification or |
| 61 | + terminal differentiation in the epidermis |
| 62 | + explanation: Describes the epidermal barrier dysfunction in atopic |
| 63 | + dermatitis including abnormal cornification and keratinocyte |
| 64 | + differentiation. |
| 65 | +- name: Type 2 Immune Response |
| 66 | + description: Th2-skewed immune response drives the hallmark inflammation. |
| 67 | + IL-4, IL-13, and IL-31 promote IgE production, eosinophil recruitment, and |
| 68 | + pruritus. IL-4/IL-13 signaling through JAK1/STAT6 further impairs barrier |
| 69 | + function by downregulating filaggrin and other barrier proteins. |
| 70 | + genes: |
| 71 | + - preferred_term: IL4 |
| 72 | + term: |
| 73 | + id: hgnc:6014 |
| 74 | + label: IL4 |
| 75 | + - preferred_term: IL13 |
| 76 | + term: |
| 77 | + id: hgnc:5973 |
| 78 | + label: IL13 |
| 79 | + - preferred_term: IL31 |
| 80 | + term: |
| 81 | + id: hgnc:19372 |
| 82 | + label: IL31 |
| 83 | + - preferred_term: STAT6 |
| 84 | + term: |
| 85 | + id: hgnc:11368 |
| 86 | + label: STAT6 |
| 87 | + downstream: |
| 88 | + - target: Epidermal Barrier Dysfunction |
| 89 | + description: IL-4 and IL-13 downregulate filaggrin expression, creating a |
| 90 | + vicious cycle of barrier disruption and immune activation. |
| 91 | + - target: Pruritogen-Induced Neuronal Activation |
| 92 | + description: IL-31 signaling contributes to neuronal itch signaling in |
| 93 | + lesional skin. |
| 94 | + biological_processes: |
| 95 | + - preferred_term: Type 2 immune response |
| 96 | + term: |
| 97 | + id: GO:0042092 |
| 98 | + label: type 2 immune response |
| 99 | + - preferred_term: T-helper 2 cell differentiation |
| 100 | + term: |
| 101 | + id: GO:0045064 |
| 102 | + label: T-helper 2 cell differentiation |
| 103 | + - preferred_term: Interleukin-4-mediated signaling pathway |
| 104 | + term: |
| 105 | + id: GO:0035771 |
| 106 | + label: interleukin-4-mediated signaling pathway |
| 107 | + - preferred_term: IgE isotype switching |
| 108 | + term: |
| 109 | + id: GO:0035708 |
| 110 | + label: interleukin-4-dependent isotype switching to IgE isotypes |
| 111 | + cell_types: |
| 112 | + - preferred_term: T-helper 2 cell |
| 113 | + term: |
| 114 | + id: CL:0000546 |
| 115 | + label: T-helper 2 cell |
| 116 | + - preferred_term: Group 2 innate lymphoid cell |
| 117 | + term: |
| 118 | + id: CL:0001069 |
| 119 | + label: group 2 innate lymphoid cell |
| 120 | + - preferred_term: Eosinophil |
| 121 | + term: |
| 122 | + id: CL:0000771 |
| 123 | + label: eosinophil |
| 124 | + - preferred_term: Mast cell |
| 125 | + term: |
| 126 | + id: CL:0000097 |
| 127 | + label: mast cell |
| 128 | + evidence: |
| 129 | + - reference: PMID:30819278 |
| 130 | + supports: SUPPORT |
| 131 | + evidence_source: HUMAN_CLINICAL |
| 132 | + snippet: Type 2 cytokines as well as interleukin 17 and interleukin 22 |
| 133 | + contribute to skin barrier dysfunction and the development of AD. |
| 134 | + explanation: Confirms the role of type 2 cytokines in AD pathophysiology and |
| 135 | + their contribution to barrier dysfunction, supporting the Th2/type 2 |
| 136 | + immune mechanism. |
| 137 | + - reference: PMID:21388665 |
| 138 | + supports: PARTIAL |
| 139 | + evidence_source: HUMAN_CLINICAL |
| 140 | + snippet: skin lesions contain immune infiltrates of T cells, dendritic |
| 141 | + cells, and other types of leukocytes. We review similarities between the |
| 142 | + diseases and differences in epidermal barrier defects and immune cells. |
| 143 | + explanation: Describes the immune cell infiltrates in AD lesions including T |
| 144 | + cells and dendritic cells, consistent with type 2 immune response. |
| 145 | +- name: Th17/Th22 Inflammation |
| 146 | + description: In addition to the dominant Th2 response, Th17 and Th22 cells |
| 147 | + contribute to inflammation, particularly in acute lesions and Asian |
| 148 | + patients. IL-17 and IL-22 further disrupt epidermal differentiation. |
| 149 | + biological_processes: |
| 150 | + - preferred_term: T-helper 17 type immune response |
| 151 | + term: |
| 152 | + id: GO:0072538 |
| 153 | + label: T-helper 17 type immune response |
| 154 | + cell_types: |
| 155 | + - preferred_term: T-helper 17 cell |
| 156 | + term: |
| 157 | + id: CL:0000899 |
| 158 | + label: T-helper 17 cell |
| 159 | +- name: Pruritogen-Induced Neuronal Activation |
| 160 | + description: IL-31 and other pruritogens activate cutaneous sensory neurons, |
| 161 | + generating persistent itch in atopic dermatitis. |
| 162 | + genes: |
| 163 | + - preferred_term: IL31 |
| 164 | + term: |
| 165 | + id: hgnc:19372 |
| 166 | + label: IL31 |
| 167 | + downstream: |
| 168 | + - target: Scratching-Induced Barrier Injury |
| 169 | + description: Persistent itch drives repetitive scratching behavior. |
| 170 | + cell_types: |
| 171 | + - preferred_term: Sensory neuron |
| 172 | + term: |
| 173 | + id: CL:0000101 |
| 174 | + label: sensory neuron |
| 175 | + evidence: |
| 176 | + - reference: PMID:30819278 |
| 177 | + supports: PARTIAL |
| 178 | + evidence_source: HUMAN_CLINICAL |
| 179 | + snippet: New insights into the pathophysiology of AD have focused on |
| 180 | + epidermal lipid profiles, neuroimmune interactions, and microbial |
| 181 | + dysbiosis. |
| 182 | + explanation: Supports neuroimmune signaling as a component of AD |
| 183 | + pathophysiology. |
| 184 | +- name: Scratching-Induced Barrier Injury |
| 185 | + description: Repetitive scratching causes mechanical skin injury and worsens |
| 186 | + epidermal barrier dysfunction. |
| 187 | + downstream: |
| 188 | + - target: Secondary Inflammatory Amplification |
| 189 | + description: Mechanical barrier injury increases local inflammatory |
| 190 | + activation. |
| 191 | + cell_types: |
| 192 | + - preferred_term: Keratinocyte |
| 193 | + term: |
| 194 | + id: CL:0000312 |
| 195 | + label: keratinocyte |
| 196 | +- name: Secondary Inflammatory Amplification |
| 197 | + description: Barrier injury from scratching perpetuates inflammatory signaling |
| 198 | + and contributes to chronic lesion persistence. |
| 199 | + biological_processes: |
| 200 | + - preferred_term: Inflammatory response |
| 201 | + term: |
| 202 | + id: GO:0006954 |
| 203 | + label: inflammatory response |
| 204 | + cell_types: |
| 205 | + - preferred_term: Keratinocyte |
| 206 | + term: |
| 207 | + id: CL:0000312 |
| 208 | + label: keratinocyte |
| 209 | +phenotypes: |
| 210 | +- name: Eczematoid Dermatitis |
| 211 | + category: Dermatological |
| 212 | + frequency: VERY_FREQUENT |
| 213 | + diagnostic: true |
| 214 | + notes: Erythematous, pruritic patches and plaques with scaling, often in |
| 215 | + flexural areas. |
| 216 | + phenotype_term: |
| 217 | + preferred_term: Eczematoid dermatitis |
| 218 | + term: |
| 219 | + id: HP:0000964 |
| 220 | + label: Eczematoid dermatitis |
| 221 | +- name: Pruritus |
| 222 | + category: Dermatological |
| 223 | + frequency: VERY_FREQUENT |
| 224 | + diagnostic: true |
| 225 | + notes: Intense itching is the hallmark symptom, often worse at night. |
| 226 | + phenotype_term: |
| 227 | + preferred_term: Pruritus |
| 228 | + term: |
| 229 | + id: HP:0000989 |
| 230 | + label: Pruritus |
| 231 | +- name: Xerosis |
| 232 | + category: Dermatological |
| 233 | + frequency: VERY_FREQUENT |
| 234 | + notes: Generalized dry skin reflecting barrier dysfunction. |
| 235 | + phenotype_term: |
| 236 | + preferred_term: Xerosis |
| 237 | + term: |
| 238 | + id: HP:0000958 |
| 239 | + label: Dry skin |
| 240 | +- name: Lichenification |
| 241 | + category: Dermatological |
| 242 | + frequency: FREQUENT |
| 243 | + notes: Thickened, leathery skin from chronic scratching. |
| 244 | + phenotype_term: |
| 245 | + preferred_term: Lichenification |
| 246 | + term: |
| 247 | + id: HP:0100725 |
| 248 | + label: Lichenification |
| 249 | +- name: Elevated Serum IgE |
| 250 | + category: Immunological |
| 251 | + frequency: FREQUENT |
| 252 | + notes: Present in extrinsic subtype (~80% of patients). |
| 253 | + phenotype_term: |
| 254 | + preferred_term: Elevated serum IgE |
| 255 | + term: |
| 256 | + id: HP:0003212 |
| 257 | + label: Increased circulating IgE concentration |
| 258 | +genetic: |
| 259 | +- name: FLG |
| 260 | + association: Associated |
| 261 | + notes: Loss-of-function variants are the strongest genetic risk factor. R501X |
| 262 | + and 2282del4 are common in European populations. |
| 263 | + evidence: |
| 264 | + - reference: PMID:16550169 |
| 265 | + supports: SUPPORT |
| 266 | + evidence_source: HUMAN_CLINICAL |
| 267 | + snippet: two independent loss-of-function genetic variants (R510X |
| 268 | + [sic, correct designation is R501X] and 2282del4) in the gene encoding |
| 269 | + filaggrin (FLG) are very strong predisposing factors for atopic |
| 270 | + dermatitis. These variants are carried by approximately 9% of people of |
| 271 | + European origin. |
| 272 | + explanation: Landmark Palmer et al. 2006 study establishing FLG |
| 273 | + loss-of-function as the major genetic predisposing factor for atopic |
| 274 | + dermatitis. |
| 275 | +- name: IL4R |
| 276 | + association: Associated |
| 277 | + notes: Variants in IL-4 receptor alpha chain affect Th2 signaling intensity. |
| 278 | +- name: IL13 |
| 279 | + association: Associated |
| 280 | + notes: Variants affecting IL-13 expression or function. |
| 281 | +- name: STAT6 |
| 282 | + association: Associated |
| 283 | + notes: Transcription factor downstream of IL-4/IL-13 signaling. |
| 284 | +- name: EMSY |
| 285 | + association: Associated |
| 286 | + notes: Chromatin remodeling factor identified in GWAS. |
| 287 | +- name: BACH2 |
| 288 | + association: GWAS |
| 289 | + notes: Transcription factor regulating Treg/effector T cell balance and B cell |
| 290 | + class switching |
| 291 | +- name: TNFAIP3 |
| 292 | + association: GWAS |
| 293 | + notes: Encodes A20, a ubiquitin-editing enzyme that negatively regulates NF-kB |
| 294 | + signaling |
| 295 | +- name: EGR2 |
| 296 | + association: GWAS |
| 297 | + notes: Transcription factor involved in T cell anergy and peripheral tolerance |
| 298 | +- name: ETS1 |
| 299 | + association: GWAS |
| 300 | + notes: Transcription factor regulating T and B cell development and immune |
| 301 | + cell differentiation |
| 302 | +- name: IRF4 |
| 303 | + association: GWAS |
| 304 | + notes: Transcription factor essential for Th17 and Th2 cell differentiation |
| 305 | + and plasma cell development |
| 306 | +- name: SATB1 |
| 307 | + association: GWAS |
| 308 | + notes: Chromatin organizer regulating T cell development and lineage |
| 309 | + commitment |
| 310 | +- name: SMAD3 |
| 311 | + association: GWAS |
| 312 | + notes: TGF-beta signaling mediator regulating T cell differentiation and |
| 313 | + immune tolerance |
| 314 | +- name: REL |
| 315 | + association: GWAS |
| 316 | + notes: NF-kB subunit c-Rel controlling lymphocyte activation and survival |
| 317 | +environmental: |
| 318 | +- name: Allergen Exposure |
| 319 | + description: House dust mites, pet dander, and pollens can trigger or |
| 320 | + exacerbate disease. |
| 321 | + effect: TRIGGERS |
| 322 | +- name: Skin Irritants |
| 323 | + description: Soaps, detergents, and harsh fabrics disrupt the already |
| 324 | + compromised barrier. |
| 325 | + effect: TRIGGERS |
| 326 | +- name: Microbial Dysbiosis |
| 327 | + description: Staphylococcus aureus colonization is found in >90% of lesional |
| 328 | + skin and amplifies inflammation through superantigens and biofilm formation. |
| 329 | + effect: WORSENS |
| 330 | +treatments: |
| 331 | +- name: Emollients and Moisturizers |
| 332 | + description: First-line treatment to restore skin barrier function and reduce |
| 333 | + transepidermal water loss. |
| 334 | +- name: Topical Corticosteroids |
| 335 | + description: First-line anti-inflammatory treatment for flares, applied to |
| 336 | + affected areas. |
| 337 | +- name: Dupilumab |
| 338 | + description: Monoclonal antibody targeting IL-4 receptor alpha, blocking both |
| 339 | + IL-4 and IL-13 signaling. FDA-approved for moderate-to-severe atopic |
| 340 | + dermatitis. |
| 341 | + treatment_term: |
| 342 | + preferred_term: pharmacotherapy |
| 343 | + term: |
| 344 | + id: MAXO:0000058 |
| 345 | + label: pharmacotherapy |
| 346 | +- name: JAK Inhibitors |
| 347 | + description: Oral (baricitinib, upadacitinib, abrocitinib) and topical |
| 348 | + (ruxolitinib) JAK inhibitors targeting the JAK-STAT pathway downstream of |
| 349 | + type 2 cytokines. |
| 350 | + treatment_term: |
| 351 | + preferred_term: pharmacotherapy |
| 352 | + term: |
| 353 | + id: MAXO:0000058 |
| 354 | + label: pharmacotherapy |
| 355 | +- name: Phototherapy |
| 356 | + description: Narrowband UVB phototherapy for moderate-to-severe disease. |
| 357 | +disease_term: |
| 358 | + preferred_term: atopic dermatitis |
| 359 | + term: |
| 360 | + id: MONDO:0004980 |
| 361 | + label: atopic eczema |
| 362 | +references: |
| 363 | +- reference: DOI:10.1007/s13555-025-01352-y |
| 364 | + title: 'Interleukin-4 and Atopic Dermatitis: Why Does it Matter? A Narrative Review' |
| 365 | + findings: [] |
| 366 | +- reference: DOI:10.1038/s41467-023-41857-8 |
| 367 | + title: Multifaceted analysis of cross-tissue transcriptomes reveals |
| 368 | + phenotype–endotype associations in atopic dermatitis |
| 369 | + findings: [] |
| 370 | +- reference: DOI:10.1126/sciimmunol.abi6887 |
| 371 | + title: IL-31–dependent neurogenic inflammation restrains cutaneous type 2 |
| 372 | + immune response in allergic dermatitis |
| 373 | + findings: [] |
| 374 | +- reference: DOI:10.1186/s43556-025-00313-3 |
| 375 | + title: 'Atopic dermatitis: diagnosis, molecular pathogenesis, and therapeutics' |
| 376 | + findings: [] |
| 377 | +- reference: DOI:10.14789/ejmj.jmj24-0036-r |
| 378 | + title: Mechanisms of Itch in Atopic Dermatitis |
| 379 | + findings: [] |
| 380 | +- reference: DOI:10.3390/jcm12041538 |
| 381 | + title: 'The Role of Tight Junctions in Atopic Dermatitis: A Systematic Review' |
| 382 | + findings: [] |
| 383 | +- reference: DOI:10.3390/jcm14145053 |
| 384 | + title: 'Anti-Inflammatory Therapies for Atopic Dermatitis: A New Era in Targeted |
| 385 | + Treatment' |
| 386 | + findings: [] |
| 387 | +- reference: DOI:10.64898/2026.01.10.26343854 |
| 388 | + title: 'Protective and Susceptibility Clusters of Environmental Factors, Gene Expression, |
| 389 | + Antibody Responses, and Cytokines in Pediatric Atopic Dermatitis: Insights from |
| 390 | + Multi-Modal Data Integration' |
| 391 | + findings: [] |
| 392 | +- reference: DOI:10.7759/cureus.86937 |
| 393 | + title: 'Skin Barrier Dysfunction in Chronic Dermatoses: From Pathophysiology to |
| 394 | + Emerging Therapeutic Strategies' |
| 395 | + findings: [] |
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