Shared Pathophysiology Modules

A conserved pathological module representing the shared core of the heritable thoracic aortic aneurysm and dissection (TAAD) syndromes. A primary genetic defect in an aortic wall component — extracellular matrix microfibrils/elastic fibers (FBN1, COL3A1, and other matrix genes), the vascular smooth muscle cell contractile apparatus (ACTA2, MYH11, MYLK, PRKG1), or the TGF-beta signaling pathway itself (TGFBR1/2, SMAD3, TGFB2/3, SKI) — converges on dysregulated, paradoxically increased TGF-beta signaling in the aortic media. Excess TGF-beta signaling together with the underlying structural defect drives medial degeneration (smooth muscle cell depletion and elastic fiber fragmentation with disordered matrix), progressively weakening the aortic wall so that it dilates and ultimately dissects or ruptures. This conserved core is shared across the syndromic aortopathies (Marfan, Loeys-Dietz, vascular Ehlers-Danlos, Shprintzen-Goldberg, arterial tortuosity) and nonsyndromic familial TAAD. Individual disorder entries declare conformance via conforms_to on their pathophysiology nodes, substituting the disorder-specific causal gene/lesion while preserving the conserved defect -> TGF-beta dysregulation -> medial degeneration -> dilation -> dissection chain.

A conserved cardiac electrophysiology mechanism module for inherited arrhythmia syndromes (channelopathies) in structurally normal hearts. Pathogenic variants in cardiac ion channels or calcium-handling proteins shift the balance of depolarizing and repolarizing currents and disturb sarcoplasmic-reticulum calcium handling. This alters cardiomyocyte action potential duration (APD) and/or diastolic calcium, generating afterdepolarization-driven triggered activity (early afterdepolarizations from prolonged APD; delayed afterdepolarizations from calcium leak). Regional heterogeneity of repolarization and conduction creates an arrhythmogenic substrate that supports reentrant and triggered ventricular tachyarrhythmia (torsade de pointes, polymorphic ventricular tachycardia, ventricular fibrillation), clinically manifesting as syncope and sudden cardiac death. A parallel branch captures the same ion-channel and pacemaker machinery acting in the sinoatrial node, where loss of function produces bradyarrhythmia and sinus arrest rather than tachyarrhythmia.

A conserved developmental and degenerative module for the ciliopathies. Diverse upstream lesions in genes encoding basal body, transition zone, and intraflagellar transport (IFT) components disrupt the assembly, gating, and cargo trafficking of the primary cilium. Because the cilium is the cell's signaling antenna, these defects converge on impaired cilium-dependent signal transduction, principally Hedgehog (smoothened) signaling and non-canonical Wnt / planar cell polarity (PCP) signaling. The shared signaling failure is read out differently in each ciliated tissue, producing the pleiotropic, multisystem phenotype that unites Bardet-Biedl, Joubert, nephronophthisis, Jeune, Alstrom, Meckel, orofaciodigital, and short-rib polydactyly syndromes: retinal degeneration, cystic-fibrotic kidney disease, skeletal dysplasia with polydactyly, cerebellar/CNS malformation, and metabolic dysfunction. A parallel motile-cilia arm captures the distinct mechanism of primary ciliary dyskinesia, in which axonemal motility defects impair mucociliary clearance and left-right body patterning. Disorder entries reference these nodes via conforms_to and substitute gene- and organ-specific cell types and lesions.

A conserved mechanism module representing isolated cytochrome c oxidase (COX, mitochondrial respiratory chain Complex IV) deficiency. Loss of a structural subunit, an assembly/maturation factor, a copper-delivery metallochaperone, or a heme A biosynthesis enzyme prevents maturation of a functional COX holoenzyme. The resulting block in terminal electron transfer (cytochrome c to molecular oxygen) and proton pumping collapses oxidative ATP synthesis, forcing anaerobic glycolysis (lactic acidosis) and producing energy failure in high-demand tissues (brain, heart, skeletal muscle, liver). The module captures the gene-agnostic core shared across the many nuclear and mtDNA causes of isolated COX deficiency; conforming disorder entries substitute the specific gene, the affected assembly sub-step, and the organ/tissue tropism while preserving this causal chain.

A conserved pathological module representing the dysregulation of normal wound healing (GO:0042060) that underlies organ fibrosis across tissues. Tissue injury triggers inflammation and resident mesenchymal cell activation, leading to myofibroblast transdifferentiation, excessive extracellular matrix deposition, and progressive architectural distortion with organ dysfunction. This module captures the shared core of fibrotic disease across liver, lung, heart, kidney, skin, and other organs. Individual disorder entries declare conformance via conforms_to on their pathophysiology nodes, substituting organ-specific cell types and anatomical locations while preserving the conserved causal chain and signaling axes.

A conserved oncology mechanism module for tumors with impaired homologous recombination repair (HRR) or FA/BRCA pathway function. HRR-deficient cells accumulate replication-associated DNA damage and become selectively vulnerable to PARP inhibition and platinum-induced DNA lesions. Therapeutic pressure can then select escape states, including POLQ-associated microhomology-mediated repair and BRCA reversion events that restore HRR. Individual disorder entries declare conformance via conforms_to on their pathophysiology nodes, preserving the conserved causal chain while substituting tumor-specific initiating genes, biomarker states, therapies, and resistance mechanisms.

A conserved pathological module representing hepatocellular endoplasmic reticulum (ER) storage disease: a mutant secretory protein misfolds during biogenesis, is retained and polymerized within the hepatocyte ER instead of being secreted, and imposes proteotoxic gain-of-function stress on the cell. Saturation of ER-associated degradation and autophagy drives chronic hepatocyte injury, and the resulting cycle of death and regeneration activates hepatic stellate cells, producing progressive fibrosis and cirrhosis. The conserved core is shared across ER storage hepatopathies, the prototype being Z alpha-1 antitrypsin (Z-AAT) polymer retention; mutant fibrinogen retention in hepatic fibrinogen storage disease (HFSD) follows the same cascade with a different stored protein. The terminal fibrotic step conforms to the conserved fibrotic response module.

A conserved mechanism module for familial adult myoclonus epilepsy caused by intronic pentanucleotide repeat expansions that contain pathogenic TTTCA insertions. Across multiple unrelated host genes, the shared repeat architecture is linked to UUUCA repeat RNA toxicity, cerebellocortical dysfunction, and cortical hyperexcitability with myoclonus and seizures.

A conserved developmental mechanism module for the germline FGFR gain-of-function skeletal dysplasias and craniosynostosis syndromes. A recurrent activating mutation in a fibroblast growth factor receptor (most commonly FGFR3, less often FGFR2 or FGFR1) produces a constitutively active or ligand-hypersensitive receptor. The resulting sustained MAPK/ERK and STAT signaling acts in two skeletogenic compartments: in growth-plate chondrocytes it drives premature exit from proliferation and dysregulated chondrocyte differentiation, impairing endochondral ossification and producing chondrodysplasia; in cranial suture mesenchyme it accelerates osteoblast differentiation and matrix mineralization, producing premature suture fusion and craniosynostosis. The physiological CNP-NPR2 pathway antagonizes FGFR3-MAPK signaling and provides the therapeutic rationale for CNP-analog and FGFR-pathway antagonist therapy.

A conserved mechanism module representing the tumor-immune cycle that checkpoint inhibitors target. Across many cancer types, tumor cells generate neoantigens that provoke anti-tumor T cell responses, but adaptively upregulate immune checkpoint ligands (PD-L1, PD-L2) and recruit immunosuppressive cells to evade destruction. Immune checkpoint blockade (anti-PD-1, anti-PD-L1, anti-CTLA-4) reverses this evasion by restoring effector T cell function. This module captures the shared causal chain from neoantigen presentation through adaptive immune resistance to T cell exhaustion, and defines the mechanism-of-action pattern for checkpoint inhibitor treatments. Individual disorder entries declare conformance via conforms_to on their pathophysiology nodes, substituting tumor-type-specific details (driver mutations, neoantigen sources, tissue-specific immune microenvironment) while preserving the conserved immune evasion and checkpoint blockade response pattern.

A conserved intestinal pathophysiology module representing convergent mechanisms that produce diarrhea through epithelial injury, junctional disruption, increased mucosal permeability, impaired absorption, and downstream fluid loss. The initiating insult varies across immune-mediated enteritides, treatment-related mucositis, dysbiosis-associated inflammation, and related disorders, but the downstream sequence repeatedly converges on barrier failure and diarrheal output.

A conserved pathological module representing the shared core of the lysosomal storage diseases (LSDs): an inherited deficiency of a specific lysosomal hydrolase (or of a non-enzymatic protein/transporter essential for normal lysosomal function) blocks catabolism of a macromolecular substrate, which then accumulates undegraded within the lysosome. Progressive intralysosomal storage distends the organelle and impairs lysosome function, triggering a secondary cascade of autophagic-flux block, disturbed signalling, mitochondrial and calcium dysregulation. The affected cell type — often only a subset of cells determined by where the substrate is normally turned over — undergoes storage-cell transformation, cytotoxicity, and (in the CNS) neuroinflammation and neurodegeneration, producing progressive multi-organ disease. This conserved core is shared across sphingolipidoses, mucopolysaccharidoses, glycoproteinoses, glycogenoses (Pompe), and free-substrate transport defects. Individual disorder entries declare conformance via conforms_to on their pathophysiology nodes, substituting the disorder-specific deficient enzyme, stored substrate, and storage cell type while preserving the conserved deficiency -> accumulation -> lysosomal dysfunction -> cytotoxicity -> multisystem disease chain.

A conserved mechanism module for inherited gametogenic failure caused by disruption of meiotic prophase I chromosome synapsis and recombination. In affected germ cells, programmed meiotic chromosome events fail at homolog pairing, synaptonemal complex assembly, homologous-recombination repair of DNA double-strand breaks, or pachytene checkpoint resolution. The shared path is meiotic arrest with germ-cell apoptosis, producing sex-dimorphic clinical outcomes: ovarian follicle depletion and primary ovarian insufficiency in 46,XX individuals, and spermatogenic arrest with non-obstructive azoospermia or Sertoli-cell-only syndrome in 46,XY individuals. This module is intended for meiotic genes such as SYCE1, MCM8, MCM9, STAG3, HFM1, MSH4, MSH5, DMC1, and SYCP3. It intentionally excludes upstream gonadal organogenesis and steroidogenic transcription-factor disorders such as NR5A1, WT1, SOX9, SRY, FOXL2, and DHH.

A conserved developmental module for Waardenburg-spectrum auditory-pigmentary disease. Diverse upstream lesions, including PAX3/SOX10/MITF transcriptional dysregulation and EDN3/EDNRB endothelin signaling deficiency, converge on impaired melanoblast migration, survival, or differentiation. This reduces melanocytes in skin, hair, iris, and the cochlear stria vascularis, producing pigmentary anomalies and sensorineural hearing impairment. Disorder entries reference these nodes via conforms_to and substitute the gene-specific trigger.

A conserved RNA-virus host-response module centered on NAD-dependent ADP-ribosylation. Viral infection and interferon signaling induce noncanonical PARPs that MARylate or PARylate host and viral proteins, restricting viral replication, shaping stress granules, and promoting innate cytokine responses. PARG and host macrodomains reset ADP-ribose marks, while viral macrodomains encoded by coronaviruses, alphaviruses, hepeviruses, and related RNA viruses erase ADP-ribose modifications to counter host antiviral defenses and support replication or pathogenesis.

A conserved neurodegeneration mechanism module for the autosomal dominant polyglutamine (polyQ) diseases caused by translated CAG trinucleotide repeat expansions. Across unrelated host genes, an elongated polyQ tract confers a dominant toxic gain of function on the disease protein: the mutant protein misfolds and aggregates (often forming neuronal intranuclear inclusions), sequesters transcriptional co-activators and disrupts gene expression, overwhelms ubiquitin-proteasome and autophagy clearance, and impairs mitochondrial bioenergetics. These convergent insults produce region-specific selective neuronal dysfunction and loss despite the disease protein being expressed widely. Individual disorder entries declare conformance via conforms_to on their pathophysiology nodes, substituting the gene-specific initiating protein, the vulnerable neuronal population, and the affected brain region while preserving the shared causal chain.

A conserved oncology mechanism module for growth-factor and receptor tyrosine kinase (RTK) programs that signal through the GRB2 adaptor hub. Activated receptors create phosphotyrosine docking sites that recruit GRB2-containing complexes, coupling upstream RTK activity to RAS-MAPK and PI3K-AKT outputs that support proliferation, survival, and drug-adaptive fitness. The module also captures the emerging nuclear GRB2 function in RAD51-dependent replication-fork protection, linking the same adaptor control point to DNA damage response, PARP-inhibitor vulnerability, and innate immune activation when fork protection is lost.