| Subtype | Canonical disease label | Causal gene / locus | Inheritance | Core hallmark phenotypes | Distinguishing features | Key quantitative findings from extracted evidence |
|---|---|---|---|---|---|---|
| FS1 | Feingold syndrome type 1 | **MYCN** (2p24.3; OMIM gene 164840) | Autosomal dominant; complete/near-complete penetrance with variable expressivity reported (pqac-00000007, pqac-00000022) | Microcephaly; brachymesophalangy of 2nd/5th fingers; toe syndactyly; short palpebral fissures; short stature; learning disability/intellectual disability; esophageal and/or duodenal atresia (pqac-00000004, pqac-00000023, pqac-00000038) | GI atresia is the major clinical discriminator from FS2; MYCN loss-of-function/haploinsufficiency is the established mechanism (pqac-00000002, pqac-00000008, pqac-00000012) | In aggregated **MYCN**-positive series (n=77): brachymesophalangy **100%**, toe syndactyly **97%**, OFC <p10 / microcephaly **89–90%**, GI atresia **55%** (esophageal **32%**, duodenal **31%**), short palpebral fissures **73%**, mild MR/learning disability **51%**, renal anomalies **18%**, cardiac anomalies **15%** (pqac-00000004, pqac-00000038, pqac-00000039). Recent review/case-series estimate pathogenic **MYCN** variants in ~**70%** of FS1 patients; ~**60%** point variants and ~**10%** deletions (pqac-00000010, pqac-00000021). In one clinically defined FS cohort, MYCN mutation/deletion detection was **47%** (7/15 evaluable cases), supporting genetic heterogeneity among clinically suspected patients (pqac-00000000, pqac-00000023). |
| FS2 | Feingold syndrome type 2 | **MIR17HG** / miR-17~92 cluster (13q31.3; OMIM phenotype 614326 referenced) | Autosomal dominant due to heterozygous deletion / haploinsufficiency (pqac-00000014, pqac-00000015, pqac-00000019) | Overlapping skeletal/growth phenotype with FS1: microcephaly, short stature, brachymesophalangy, clinodactyly/toe syndactyly, learning/neurocognitive issues (pqac-00000015, pqac-00000017, pqac-00000018) | Usually **lacks gastrointestinal atresia**; some reports expand phenotype to congenital heart disease, hearing loss, growth hormone deficiency, aortic dilation, neurocognitive/psychiatric issues (pqac-00000015, pqac-00000017, pqac-00000018) | Reported literature up to 2015 described **10** individuals with deletions involving **MIR17HG**; those ten had microcephaly, short stature, brachymesophalangy, and learning disabilities (pqac-00000015). Additional cited summary: brachymesophalangia **100% (16/16)**, short stature **81% (13/16)**, fifth-finger clinodactyly **68% (11/16)** (pqac-00000001). Cardiac anomalies were reported in **50%** of FG2 patients in whom cardiac examination was described in one review of published cases/series (pqac-00000017). |
| Cross-subtype comparison | Feingold syndrome (disease-level summary; OMIM 164280, ORPHA 391641 reported for Feingold syndrome) | FS1 = **MYCN**; FS2 = **MIR17HG** | Mendelian, autosomal dominant | Shared syndrome core = microcephaly + characteristic digital anomalies + variable developmental issues; disease-level data come from aggregated case series/case reports rather than EHR-derived datasets (pqac-00000005, pqac-00000022, pqac-00000023) | Mechanistically distinct despite phenotypic overlap: **MIR17HG/miR-17~92 deficiency upregulates TGF-β signaling**, whereas **MYCN deficiency downregulates PI3K signaling** in limb mesenchymal cells; MYCN also transcriptionally regulates miR-17~92 (pqac-00000008, pqac-00000019) | Historical/clinical summaries note Feingold syndrome is probably the most frequent single-gene cause of esophageal and duodenal atresia, with esophageal/duodenal atresia in about **1/3** of reported patients in older summaries (pqac-00000007), whereas larger aggregated MYCN datasets place GI atresia closer to **55%** among molecularly confirmed carriers (pqac-00000038). More than **120** patients/families with FS1 had been reported in the literature by recent case-series/reviews (pqac-00000005, pqac-00000021). |


*Table: This table summarizes the core knowledge-base facts for Feingold syndrome, contrasting FS1 and FS2 by causal gene, inheritance, hallmark phenotype pattern, and the most useful quantitative statistics extracted from the cited literature. It is designed for rapid disease-entry curation and genotype-phenotype comparison.*