Pseudohypoaldosteronism Type IB3 Autosomal Recessive

1. Disease Information

• What it is: A rare hereditary channelopathy of aldosterone resistance (pseudohypoaldosteronism) in its severe systemic form, caused by defective ENaC. "Pseudo"-hypoaldosteronism because aldosterone levels are normal/high but its downstream effect (ENaC-mediated Na⁺ reabsorption) is absent. PMID 42549990: "Pseudohypoaldosteronism type 1 (PHA1) is a rare hereditary disorder characterised by aldosterone resistance leading to salt wasting, hyperkalaemia, and metabolic acidosis… a severe systemic form (PHA1B) caused by biallelic mutations in epithelial sodium channel (ENaC) subunit genes."
• Key identifiers:
• OMIM: 620126 (Pseudohypoaldosteronism, type IB3, autosomal recessive)
• MONDO: MONDO:0859318
• Gene: SCNN1G (HGNC:10601; NCBI Gene 6340; Ensembl ENSG00000166828; UniProt P51170), chromosome 16p12.2
• Orphanet: PHA type 1 (ORPHA:171876 generalized/systemic PHA1; parent ORPHA:171871 for PHA1)
• ICD-10: E27.4 (other and unspecified adrenocortical insufficiency; PHA has no dedicated ICD-10 code); ICD-11: 5A71.Z/5A7Y adrenal-related; often coded under disorders of mineralocorticoid action
• MeSH: D011546 "Pseudohypoaldosteronism"
• Synonyms / alternative names: Systemic pseudohypoaldosteronism type 1; generalized PHA1; multiple-target-organ defect PHA1; autosomal recessive PHA type 1 (γ-ENaC type); PHA1B3; gamma-ENaC–related systemic PHA.
• Information source type: Derived chiefly from disease-level aggregated resources (OMIM, Orphanet) and individual-patient case reports/small case series (ultra-rare disease; no large EHR cohorts).

2. Etiology

• Primary cause — genetic: Biallelic (homozygous or compound-heterozygous) loss-of-function variants in SCNN1G. Inheritance is autosomal recessive. This is a monogenic Mendelian disease; there are no infectious or acquired primary causes of this specific (inherited) subtype. (A phenotypically similar but genetically distinct entity, secondary/transient PHA, is acquired — see §10 differentials.)
• Genetic risk factors:
• Causal variants: biallelic SCNN1G null/hypomorphic alleles (see §4).
• Parental consanguinity is a major risk factor (homozygosity for founder/private alleles). PMID 42549990: "parental consanguinity was present in seven (78%)." PMID 33690157: "All parents were consanguineous and of South Asian, Middle Eastern or African ethnic origin."
• Family history of an affected sib (25% recurrence risk per pregnancy).
• Environmental risk factors: None cause the disease. However, salt loss, intercurrent illness, vomiting/diarrhea, heat, and poor sodium intake precipitate or worsen salt-wasting crises in genetically affected individuals (gene–environment interaction: dietary sodium availability modulates crisis frequency). Mouse data directly demonstrate diet dependence — a high-Na/low-K "rescue diet" normalizes the phenotype and reverting to regular diet reinstates severe disease (PMID 26701978).
• Protective factors: No genetic protective alleles described. Aggressive dietary sodium supplementation and potassium restriction are protective against crises (environmental/therapeutic). Residual ENaC function from hypomorphic missense alleles is "protective" relative to null alleles (milder disease; see §4/§9).
• Gene–environment interaction: Dietary Na⁺/K⁺ intake is the dominant modifiable factor interacting with the fixed genetic defect to set clinical severity and crisis risk.

3. Phenotypes

Onset is neonatal (congenital functional defect); presentation typically within the first 2 weeks of life (median ~14 days; PMID 42549990, 33690157). Severity is usually severe in the classic systemic form; variable/milder with partial-function alleles. Course is episodic/crisis-prone on a chronic lifelong baseline (systemic form does not remit).

• Quality-of-life impact: High treatment burden (frequent oral medication/dose titration, salt supplements, resins, repeated electrolyte monitoring, risk of acute crises). PMID 42569709: "This condition requires a lifelong close follow-up and treatment process." Survivors with good control can achieve normal physical/neurological development and even pregnancy (PMID 33690157). No formal EQ-5D/SF-36 data for this ultra-rare disease.

4. Genetic / Molecular Information

• Causal gene: SCNN1G (sodium channel epithelial 1 gamma subunit), chromosome 16p12.2 (historically mapped 16p12.2–13.11 alongside SCNN1B). HGNC:10601; OMIM gene 600761; disease OMIM 620126. Encodes γ-ENaC (~649 aa; UniProt P51170).
• Pathogenic variants (germline; this disease has no somatic basis):
• Variant classes: splice-site, nonsense, framesh4ift (frameshift), missense, and large/gross deletions — all converging on loss of function. Landmark: PMID 8640238 — SCNN1G 3′ splice-site 318-1 G→A, truncating γ-ENaC from 649→134 aa. Recent: first homozygous gross deletion in a PHA1 ENaC gene (PMID 41275343); novel homozygous SCNN1G variants across case series (PMID 42549990).
• Classification: per ACMG/AMP — pathogenic/likely pathogenic for null alleles; some novel variants remain VUS pending functional/segregation data (PMID 42549990).
• Allele frequency: Pathogenic alleles are extremely rare in gnomAD (private/founder); loss-of-function constraint for SCNN1G is modest (recessive gene).
• Functional consequence: Loss of function — reduced channel number and/or reduced open probability. Example: γ-ENaC A635V (c.1904C>T) reduced amiloride-sensitive current ~30% with lower open probability (PMID 40153144); G532S → mild PHA-1B3 (PMID 40969802).
• Modifier genes: The other ENaC subunits (SCNN1A, SCNN1B) and regulators (NEDD4L, SGK1, CAP serine proteases, kallikrein-1) plausibly modify residual channel activity; co-expression/digenic contributions have been proposed in a network-medicine analysis (PMID 41569463). No validated clinical modifier locus specific to PHA1B3.
• Epigenetic information: No disease-specific DNA-methylation/histone data reported for PHA1B3. (Aldosterone/MR signaling epigenetically regulates ENaC transcription physiologically, but this is not altered as the primary lesion.)
• Chromosomal abnormalities: Point mutations and intragenic deletions predominate; a homozygous gross (multi-exon) deletion of an ENaC gene has been reported (PMID 41275343). No recurrent aneuploidy/translocation.
• Allelic contrast: Gain-of-function SCNN1G (PY-motif loss, e.g., Q591X) → Liddle syndrome (PMID 35661050) — demonstrating ENaC activity as the salt-retention↔salt-wasting axis.

Ontology: gene product GO:0034765 (regulation of ion transmembrane transport); protein class CHEBI/ion channel; variant effect "loss_of_function."

5. Environmental Information

• Environmental/toxic/occupational factors: None cause PHA1B3 (purely genetic).
• Lifestyle/dietary factors: Dietary sodium and potassium intake are the key modifiable determinants of crisis frequency and severity (see §2 gene–environment interaction). Heat exposure → sweat Na⁺ loss can precipitate crises (sweat gland ENaC defect).
• Infectious agents: Not causal. Intercurrent infections (and, for the acquired mimic, urinary tract infection/obstruction in secondary PHA) can precipitate salt-wasting episodes but are not the cause of the inherited disease.

6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation)

1. Biallelic loss-of-function variant in SCNN1G → produces a non-functional or hypomorphic γ-ENaC subunit (truncation, misassembly, or reduced open probability). (Demonstrated: in-vitro electrophysiology, PMID 40153144.)
2. Defective γ-subunit → impaired assembly/proteolytic activation of the αβγ-ENaC heterotrimer at the apical membrane (γ-ENaC GRIP-domain cleavage is required to relieve autoinhibition and open the channel). (Demonstrated mechanism of ENaC gating, PMID 42463047.)
3. Non-functional ENaC → loss of amiloride-sensitive apical Na⁺ reabsorption in principal/epithelial cells of ENaC-expressing tissues. (Demonstrated.)
4. In the distal nephron (connecting tubule/collecting duct) → reduced Na⁺ reabsorption → renal salt wasting → hyponatremia and hypovolemia. Loss of the lumen-negative transepithelial potential → reduced K⁺ and H⁺ secretion → hyperkalemia and metabolic acidosis. (Demonstrated; mirrored in conditional αENaC-KO mice, PMID 26701978.)
5. Hypovolemia + hyperkalemia → marked activation of renin–angiotensin–aldosterone system → very high plasma renin and aldosterone, which cannot act because the effector channel is defective ("pseudo"-hypoaldosteronism). (Demonstrated.)
6. Branch A (kidney/colon): ongoing Na⁺ wasting via gut (intestinal salt wasting/diarrhea) compounds hyponatremia.
7. Branch B (sweat/salivary glands): failure of ductal Na⁺ reabsorption → elevated sweat/saliva Na⁺/Cl⁻ (CF-like); hypertonic sweat → sweat-gland inflammation and skin lesions (miliaria-like, eczematous). (Demonstrated histologically, PMID 3654220.)
8. Branch C (airway): loss of ENaC-mediated airway surface liquid absorption → impaired mucus clearance / fluid handling → recurrent respiratory symptoms; neonatally, failure to clear fetal lung liquid is lethal in constitutive KO mice (PMID 9326675) — an inferred contributor to neonatal respiratory vulnerability in humans.
9. Severe hyponatremia + hyperkalemia → cardiac arrhythmia/arrest, dehydration, shock → neonatal death or hypoxic-ischemic neurological injury if untreated. (Demonstrated clinically, PMID 33690157.)

Supporting detail

• Molecular pathways: Aldosterone–mineralocorticoid-receptor → ENaC Na⁺ transport pathway (Reactome R-HSA-1799339 "ENaC"; KEGG "aldosterone-regulated sodium reabsorption" hsa04960). Proteolytic activation by furin/CAPs/kallikrein-1 (PMID 42463047, 41671061).
• Protein dysfunction: Loss-of-function of a trimeric ion channel; cryo-EM structure of human αβγ-ENaC available (PMID 30251954) supports structural interpretation of variants.
• Cellular processes: Defective transepithelial Na⁺ transport; secondary sweat-gland inflammation (destructive inflammatory reaction, PMID 3654220).
• Biochemical abnormality: Ion-channel defect (not an enzyme deficiency) → electrolyte/acid-base derangement.
• Immune/metabolic/epigenetic: No primary autoimmune or metabolic component; skin inflammation is secondary to hypertonic sweat.
• Molecular profiling: No disease-specific transcriptomic/proteomic/metabolomic datasets; a systems-medicine interactome highlights sodium-ion-transport and aldosterone-regulated reabsorption processes (PMID 41569463).

Ontology: GO:0006814 (sodium ion transport), GO:0035725 (sodium ion transmembrane transport), GO:0050891 (multicellular organismal water homeostasis), GO:0003051 (angiotensin-mediated regulation of ECF volume); CL:1000714 (kidney collecting duct principal cell), CL:1000454 (kidney collecting duct epithelial cell), CL:0002254 (epithelial cell of distal tubule), CL:0000078 (epithelial cell of sweat gland duct / CL:1000296), CL:0002633 (respiratory epithelial cell).

7. Anatomical Structures Affected

• Organ level (primary): Kidney (distal nephron: connecting tubule, cortical/medullary collecting duct) — UBERON:0001232 (collecting duct), UBERON:0004135 (connecting tubule). Distal colon (UBERON:0001157). Sweat glands (UBERON:0001820) and salivary glands (UBERON:0001044). Lung/airway (UBERON:0001005 respiratory airway; UBERON:0002186 bronchiole).
• Secondary/complication organs: Heart (hyperkalemic arrhythmia; UBERON:0000948), brain (hypoxic-ischemic injury post-arrest; UBERON:0000955), skin (UBERON:0002097) with sweat-gland inflammation.
• Body systems: Endocrine (mineralocorticoid signaling), renal/urinary, gastrointestinal, integumentary, respiratory; cardiovascular and nervous secondarily.
• Tissue/cell level: Epithelial tissue — Na⁺-reabsorbing principal cells of the collecting duct, distal colonic enterocytes, sweat/salivary duct epithelial cells, airway epithelial cells. CL terms as in §6.
• Subcellular level: Apical plasma membrane (GO:0016324) — ENaC resides on the apical membrane of multiciliated/epithelial cells (and in cilia; PMID 26772908); trafficking involves ER/Golgi (furin cleavage) and membrane recycling (NEDD4L/ubiquitin). GO CC: GO:0016324 (apical plasma membrane), GO:0034707 (chloride channel complex – N/A), GO:0005886 (plasma membrane).
• Localization/lateralization: Systemic and bilateral/symmetric (both kidneys, generalized skin/gland involvement).

8. Temporal Development

• Onset: Congenital/neonatal, typically acute salt-wasting crisis in the first days–2 weeks of life (median ~14 days; PMID 42549990). Milder hypomorphic alleles may present later or more insidiously (PMID 40153144).
• Progression: No formal staging. Natural history = chronic lifelong disease with recurrent episodic crises superimposed on a persistent requirement for sodium/potassium management. The most dangerous window is the neonatal/infantile period (highest mortality). Symptoms/medication needs often ease but do not disappear with age (PMID 41569463: "symptoms tend to improve with age") — in contrast to renal PHA1A, which can remit in childhood.
• Patterns: No spontaneous remission in the systemic form; "improvement" reflects maturation of compensatory mechanisms and better tolerance, not cure. Critical period / window of opportunity: rapid neonatal recognition and correction of hyperkalemia/hyponatremia is life-saving (PMID 42569709).

9. Inheritance and Population

• Epidemiology: Ultra-rare. Orphanet classifies PHA type 1 as a rare disease (point prevalence <1/1,000,000); the systemic (ENaC) form is rarer than the renal (NR3C2) form, and PHA1B3 (SCNN1G) is one of three systemic subtypes. Precise incidence/prevalence figures are unavailable; data come from case reports/small series. Neonatal hyponatremia series find genetic hypo-/pseudo-hypoaldosteronism in a few percent of referred cases (PMID 31300884).
• Inheritance: Autosomal recessive. 25% recurrence risk for sibs of an affected child.
• Penetrance / expressivity: Essentially complete penetrance of the biochemical phenotype with biallelic null alleles; variable expressivity with partial-function alleles (§4).
• Anticipation / mosaicism: Not applicable (not a repeat disorder; no reported germline mosaicism relevant to AR transmission).
• Founder effects: Yes — a shared SCNN1G 318-1 G→A haplotype in Indian-subcontinent families (PMID 8640238).
• Consanguinity: Strong driver (78%–100% of reported families; PMID 42549990, 33690157).
• Carrier frequency: Not formally established; carriers (parents) are asymptomatic.
• Population demographics: Higher among South Asian, Middle Eastern, and African / consanguineous populations (PMID 33690157). Sex ratio ≈ 1:1 (autosomal). Age distribution: overwhelmingly neonates/infants at diagnosis.

10. Diagnostics

• Laboratory (LOINC-codable): Serum Na⁺ (LOINC 2951-2) ↓, K⁺ (2823-3) ↑, bicarbonate/CO₂ ↓ with hyperchloremic metabolic acidosis; plasma renin activity ↑↑ and serum/plasma aldosterone ↑↑ (hyperreninemic hyperaldosteronism); inappropriately high urine sodium; elevated sweat chloride (LOINC 2075-0) and salivary Na⁺. Normal 17-hydroxyprogesterone (LOINC 1668-3) and cortisol help exclude CAH/adrenal insufficiency (PMID 42549990).
• Biomarkers: Aldosterone and renin (markedly elevated); sweat/salivary electrolytes; SCNN1G genotype is the definitive marker.
• Imaging: Non-specific; used to exclude adrenal pathology (adrenal ultrasound) and renal tract anomalies (to exclude secondary PHA from obstruction/reflux).
• Electrophysiology: ECG for hyperkalemic changes (peaked T waves, widened QRS) — critical acute monitoring. Research: Ussing-chamber/two-electrode voltage clamp confirm reduced amiloride-sensitive current for VUS (PMID 40153144).
• Biopsy/pathology: Not required for diagnosis; sweat-gland biopsy historically showed peri-ductal destructive inflammation (PMID 3654220).
• Genetic testing (definitive): Clinical/whole-exome sequencing or targeted ENaC/PHA gene panels covering SCNN1A, SCNN1B, SCNN1G + NR3C2 (± secondary genes); single-gene or deletion/duplication (CNV/MLPA) analysis for gross deletions (PMID 41275343). PMID 42549990: "Genetic testing was performed using clinical exome sequencing, and variants were classified according to… (ACMG) guidelines." Early genetic testing is advocated because PHA1A vs PHA1B cannot be distinguished clinically/biochemically at presentation (PMID 31301676).
• Clinical criteria: No formal consensus criteria; diagnosis = neonatal salt wasting + hyperreninemic hyperaldosteronism + ENaC-gene biallelic variants.
• Differential diagnosis: salt-wasting CAH (21-hydroxylase deficiency — high 17-OHP; PMID 27485500); aldosterone synthase deficiency (CYP11B2); primary adrenal insufficiency / adrenal hypoplasia congenita (NR0B1); familial glucocorticoid deficiency (MC2R); Bartter syndrome type II (transient neonatal hyperkalemia then hypokalemic alkalosis; PMID 40630717); renal PHA1A (NR3C2, milder/remitting); secondary/transient PHA (UTI/obstructive uropathy).
• Screening: Not on routine newborn screening. Cascade/carrier testing for consanguineous families; prenatal/preimplantation testing possible once the familial variant is known.

11. Outcome / Prognosis

• Mortality: High in the neonatal/infantile period. 25% mortality (3/12) with 16% severe neurological impairment post-hyperkalemic cardiac arrest in a UK cohort (PMID 33690157); 67% (6/9) died in an Indian series with limited resources (PMID 42549990). Deaths are driven by hyperkalemic cardiac arrest and crises.
• Life expectancy / survival: With early diagnosis and intensive lifelong management, normal survival and development are achievable; PMID 33690157: "survival with normal physical and neurological outcome is possible, justifying intensive management." One survivor had a successful pregnancy at age 28.
• Morbidity / disability: Recurrent electrolyte crises, growth faltering, skin disease, respiratory symptoms; neurodevelopmental sequelae mainly from hypoxic-ischemic events during crises.
• Complications: Hyperkalemic arrhythmia/arrest, hypovolemic shock, failure to thrive, recurrent infections/respiratory disease, nephrocalcinosis (from therapy) and treatment burden.
• Prognostic factors: Residual ENaC function (allele type) — null/truncating = severe; hypomorphic missense = milder (§4/§9); speed of neonatal recognition and adequacy of electrolyte control; access to care. No validated molecular prognostic biomarker beyond genotype.

12. Treatment

No cure or disease-modifying/gene therapy exists; management is supportive and lifelong. Mineralocorticoids (fludrocortisone) are ineffective because the defect is downstream of the receptor.

• Acute crisis: IV normal saline/volume resuscitation; aggressive hyperkalemia management (calcium gluconate for cardioprotection; insulin-glucose, β-agonists to shift K⁺; cation-exchange resins to remove K⁺); correction of acidosis with sodium bicarbonate/citrate. (NCIT: fluid resuscitation; electrolyte management.)
• Chronic maintenance (mainstays):
• High-dose oral sodium chloride (salt) supplementation — CHEBI:26710 (sodium chloride); NCIT:C83164 (sodium chloride). Doses are high and require frequent titration (PMID 42569709).
• Sodium bicarbonate / sodium citrate for metabolic acidosis (CHEBI:32139; NCIT sodium bicarbonate).
• Potassium-lowering therapy: sodium polystyrene sulfonate (Kayexalate) or calcium polystyrene sulfonate resins, often decanted into feeds for infants (PMID 38288475: "successfully managed with sodium polystyrene sulfonate decanted into feeds along with sodium supplementation"). Newer K⁺ binders (patiromer, sodium zirconium cyclosilicate) are options in principle.
• Dietary potassium restriction.
• Pharmacogenomics: Not applicable (no genotype-directed drug metabolism issue). Treatment is genotype-informed in that systemic (ENaC) disease mandates lifelong therapy vs potential weaning in renal PHA1A.
• Advanced/experimental therapeutics: No approved gene/cell/RNA therapy. ENaC biology is an active drug target in the opposite direction (ENaC inhibitors for cystic fibrosis; PMID 42184559) — not applicable to loss-of-function PHA. No disease-specific clinical trials (no NCT identifiers specific to PHA1B3).
• Surgical/rehabilitative: None specific; supportive nutrition/growth support; respiratory care as needed.
• Treatment strategy: Early molecular diagnosis → lifelong high-sodium + K⁺-binder regimen with frequent electrolyte-guided dose adjustment; multidisciplinary team (endocrinology, nephrology, dietetics) (PMID 35918792).

13. Prevention

• Primary prevention: Not possible for an inherited monogenic disease. Genetic counseling for consanguineous couples and families with an affected child; carrier testing, and where desired prenatal diagnosis / preimplantation genetic testing once the familial SCNN1G variant is known (25% recurrence risk).
• Secondary prevention (early detection): High index of suspicion for any neonate with hyponatremia + hyperkalemia + acidosis; rapid genetic testing to subtype and guide therapy (PMID 31301676). Not part of standard newborn blood-spot screening.
• Tertiary prevention (complication avoidance): Strict electrolyte control, written sick-day/crisis plans, prompt management of intercurrent illness, avoidance of K⁺-raising drugs and excessive heat/sweat losses, regular cardiac (ECG) and growth monitoring.
• Immunization / public-health / environmental interventions: Not applicable (non-infectious, non-environmental cause); routine childhood immunization and infection prevention reduce crisis triggers.

14. Other Species / Natural Disease

• Taxonomy / orthologs: ENaC subunits are conserved across tetrapods (PMID 26772908: four ENaC paralogs in most Sarcopterygii). Human SCNN1G orthologs: mouse Scnn1g (NCBI Gene 20278; Mus musculus, NCBI:txid10090), rat Scnn1g (Rattus norvegicus, NCBI:txid10116).
• Natural disease in animals: No well-characterized spontaneous SCNN1G-PHA described in companion animals (not a recognized OMIA entry for γ-ENaC PHA). Disease knowledge is from engineered models, not natural occurrence.
• Comparative biology: ENaC's dual role in renal salt handling and airway/lung-liquid clearance is conserved; mouse knockouts reveal the lung-liquid role that is harder to observe clinically in humans. Evolutionary conservation of the αβγ architecture underpins model validity.
• Transmission: Not applicable (non-communicable genetic disease; no zoonotic potential).

15. Model Organisms

• Mouse (primary model; Mus musculus, MGI):
• Constitutive αENaC (Scnn1a) knockout — neonatal lethal from failure to clear fetal lung liquid (PMID 9326675): "inactivation of alphaENaC results in failure to clear fetal lung liquid at birth and in early neonatal death."
• Transgenically rescued αENaC⁻/⁻Tg — reproduces systemic PHA-1: "alphaENaC(−/−)Tg mice showed clinical features of severe PHA-1 with metabolic acidosis, urinary salt-wasting, growth retardation, and 50% mortality"; adults show compensated PHA-1 with 6-fold elevated aldosterone (PMID 9326675). This is the classic mouse model for PHA-1.
• Conditional, adult nephron-specific αENaC knockout (Scnn1a^Pax8/LC1) — hyperkalemia and weight loss on normal diet, rescued by high-Na/low-K diet, "thus mimicking PHA-1" (PMID 26701978) — isolates the renal phenotype and demonstrates diet dependence.
• αENaC-deficient (rescued) mice — impaired respiratory Na⁺ transport predisposing to pulmonary oedema (PMID 15308680) — models the airway dimension.
• γENaC-specific mouse mutants (e.g., distal polybasic-tract/cleavage-site mutants) illuminate γ-subunit proteolytic activation and sodium conservation (PMID 42037165).
• In-vitro / heterologous systems: Xenopus oocytes and mammalian cells with two-electrode/patch-clamp electrophysiology are the standard for functionally classifying SCNN1G variants (PMID 40153144, 40969802); cryo-EM of human ENaC provides structural context (PMID 30251954).
• Phenotype recapitulation: Mouse models reproduce salt wasting, hyperkalemia, acidosis, hyperaldosteronism (renal/systemic PHA) and the neonatal lung-liquid phenotype. Limitations: constitutive KO lethality necessitates transgenic/conditional strategies; models are predominantly αENaC-based (direct biallelic Scnn1g-null disease models are less commonly reported); species differences in ENaC proteolysis exist.
• Resources: MGI (Scnn1g MGI gene), IMPC/KOMP, IMSR for strain availability.

Supported vs Refuted Hypotheses

Supported (evidence-based): - PHA1B3 is caused by biallelic LoF SCNN1G (γ-ENaC) variants → systemic aldosterone resistance. ✔ (PMID 42549990, 40969802, 8640238) - Neonatal salt-wasting triad with hyperreninemic hyperaldosteronism. ✔ (PMID 42549990, 33690157) - Multi-organ (systemic) involvement incl. sweat/salivary/skin/airway. ✔ (PMID 3654220, 26772908) - Loss-of-function mechanism with genotype-severity correlation. ✔ (PMID 40153144, 31301676) - Mouse ENaC-KO recapitulates PHA-1. ✔ (PMID 9326675, 26701978) - Ultra-rare AR disease, consanguinity/founder effects. ✔ (PMID 33690157, 8640238)

Refuted / excluded: - Mineralocorticoid (fludrocortisone) therapy is effective — refuted; defect is downstream of MR. - Disease is renal-limited — refuted; systemic multi-organ disease (distinguishes from PHA1A/NR3C2). - Caused by gain-of-function — refuted; GoF SCNN1G causes Liddle syndrome instead (PMID 35661050).

Limitations & Future Directions

• Ultra-rarity → no large cohorts, no formal prevalence/QoL/natural-history statistics; evidence skewed to case reports.
• Most mechanistic/model data are αENaC-centric; γENaC(Scnn1g)-null disease models and SCNN1G-specific genotype-phenotype datasets are limited.
• No approved targeted therapy; LoF channelopathies are not yet correctable — potential future directions: read-through/ASO for specific alleles, channel-activating small molecules, or gene/base-editing (all pre-clinical).

Evidence source types: human clinical (case series/reports, functional patient studies), model organism (mouse), in vitro (heterologous electrophysiology), computational/structural (cryo-EM, network medicine).

Artifacts

• OpenScientist final report
• OpenScientist final report

Reference Validation

Checked with linkml-reference-validator 0.4.0.

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

• HP:0002902 (1 mention) - the report calls it "Lab abnormality"; HP calls it Hyponatremia
• HP:0002153 (1 mention) - the report calls it "Lab abnormality"; HP calls it Hyperkalemia
• HP:0001942 (1 mention) - the report calls it "Lab abnormality"; HP calls it Metabolic acidosis
• HP:0000859 (1 mention) - the report calls it "Lab abnormality"; HP calls it Increased circulating aldosterone concentration
• HP:0001944 (1 mention) - the report calls it "Clinical sign"; HP calls it Dehydration
• HP:0002013 (1 mention) - the report calls it "Symptom"; HP calls it Vomiting
• HP:0001254 (1 mention) - the report calls it "Symptom"; HP calls it Lethargy
• HP:0002028 (1 mention) - the report calls it "Clinical sign"; HP calls it Chronic diarrhea
• NCIT:C83164 (1 mention) - the report calls it "sodium chloride"; NCIT calls it Birth Year

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

• GO:0050891 (1 mention) - the report calls it "multicellular organismal water homeostasis"; GO calls it multicellular organismal-level water homeostasis, and lists "multicellular organismal water homeostasis" among its other names
• GO:0003051 (1 mention) - the report calls it "angiotensin-mediated regulation of ECF volume"; GO calls it angiotensin-mediated drinking behavior
• CL:1000714 (1 mention) - the report calls it "kidney collecting duct principal cell"; CL calls it kidney cortex collecting duct principal cell
• CL:0002254 (1 mention) - the report calls it "epithelial cell of distal tubule"; CL calls it epithelial cell of small intestine
• CL:0002633 (1 mention) - the report calls it "respiratory epithelial cell"; CL calls it respiratory basal cell
• UBERON:0004135 (1 mention) - the report calls it "connecting tubule"; UBERON calls it distal tubule, and lists "kidney distal tubule" among its other names
• UBERON:0001157 (1 mention) - the report calls it "Distal colon"; UBERON calls it transverse colon
• UBERON:0002097 (1 mention) - the report calls it "skin"; UBERON calls it skin of body, and lists "skin" among its other names
• GO:0016324 (2 mentions) - the report calls it "Apical plasma membrane", "apical plasma membrane", "Subcellular level: Apical plasma membrane"; GO calls it apical plasma membrane
• GO:0034707 (1 mention) - the report calls it "chloride channel complex – N/A"; GO calls it chloride channel complex

Terms named inconsistently

The report gives these identifiers more than one name of its own:

• GO:0016324 - called "Apical plasma membrane", "apical plasma membrane", "Subcellular level: Apical plasma membrane"

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: ORPHA.