# NM_001128178.3(NPHP1):c.973C>T (p.Arg325Cys)

https://sugi.bio/variant/nphp1-p-arg325cys

## Summary

**NPHP1 p.Arg325Cys (c.973C>T)** is classified **Uncertain significance** in NPHP1 (ClinVar, Single submitter, 1 submitter; last evaluated 2022-08-22). AlphaMissense: likely benign (0.1542); Very rare (popmax 0.00667%, amr); Associated with nephronophthisis.

**At a glance:** Uncertain significance · review: Single submitter · rsID rs748435719 · 1 submitter · 1 linked condition · AlphaMissense likely benign · very rare (popmax 0.00667%, amr)

## For patients & families {#patients}

This is a change in the NPHP1 gene that is currently of uncertain significance — a definitive interpretation has not yet been established, submitted by 1 submitter, and is linked to nephronophthisis.

*Reference information, not medical advice, and not a prediction for any individual. A genetic counselor or clinician can interpret what it means for you and your family.*

|  |  |
| --- | --- |
| Typical inheritance (of this condition) | Autosomal recessive |
| Age of onset (of this condition) | Adolescent, Adult, Antenatal, Childhood, Infancy, Neonatal |
| Prevalence | 1-9 / 100 000 (Finland) |
| Clinical trials | 6 registered for this condition — see ClinicalTrials.gov |
| Diagnostic panels | NPHP1 is a diagnostic-grade gene on 18 Genomics England panels |

**Commonly reported features of Nephronophthisis** (across patients with this condition; presentation varies — frequencies from Orphanet):

- Renal insufficiency — Frequent (79-30%)
- Anemia — Frequent (79-30%)
- Abnormality of retinal pigmentation — Frequent (79-30%)

**Support & next steps:** [Condition overview & support (NIH GARD)](https://rarediseases.info.nih.gov/diseases/0000206/index) · [Find a genetic counselor (NSGC)](https://findageneticcounselor.nsgc.org/).

## Identity {#identity}

| Field | Value |
| --- | --- |
| Gene | [NPHP1](https://sugi.bio/atlas/gene/NPHP1/) |
| Protein change (HGVS p.) | p.Arg325Cys |
| Coding change (HGVS c.) | c.973C>T |
| MANE Select transcript | [NM_001128178](https://www.ncbi.nlm.nih.gov/nuccore/NM_001128178) |
| dbSNP | [rs748435719](https://www.ncbi.nlm.nih.gov/snp/rs748435719/) |
| Variant type | single nucleotide variant |
| Location | chr2:110160237-110160237 (GRCh38) |
| ClinVar | [VCV1015180](https://www.ncbi.nlm.nih.gov/clinvar/variation/1015180/) |

**All HGVS expressions:** `NC_000002.11:g.110917814G>A`, `NC_000002.12:g.110160237G>A`, `NG_008287.1:g.49826C>T`, `NM_000272.5:c.1141C>T`, `NM_001128178.3:c.973C>T`, `NM_001128179.3:c.784C>T`, `NM_001374256.1:c.970C>T`, `NM_001374257.1:c.973C>T`, `NM_207181.4:c.1138C>T`

## Computational & population evidence {#evidence}

**Concordance:** ClinVar classifies this **uncertain**; the computational predictors unanimously lean **tolerated** — a triage signal, not a reclassification.

- AlphaMissense **likely benign** (0.1542)
- REVEL 0.638 (indeterminate)
- SaProt LLR -7.113 (tolerated) — agrees with AlphaMissense
- → **In-silico consensus:** AlphaMissense and SaProt both call this tolerated; REVEL is indeterminate
- Conservation: phyloP 8.442, GERP 1.69, phastCons 1 — highly conserved (differs from AlphaMissense)
- ⚠ **Isoform check:** AlphaMissense is numbered on a different transcript (AM **R380C** vs ClinVar **R325C**) — the AlphaMissense read here may be for a different residue; verify against the ClinVar transcript.
- CADD: **PHRED 31.0**. No single ClinGen-calibrated threshold exists and the expert panels that use CADD disagree — GUCY2D/AIPL1 require ≥ 20.0 for an untranslated-region variant, ABCA4 ≥ 28.1 for a synonymous or indel variant, the Pulmonary Hypertension panel imports Pejaver 2022's missense-calibrated numbers, and the Antibody Deficiencies panel declines CADD entirely for PIK3CD. CADD v1.7 also incorporates Zoonomia phyloP, so it partly re-expresses the conservation above. *Descriptive; no threshold applied.*
- Regional missense constraint: **o/e 0.96** across the covering region of the MANE Select transcript (110,123,794–110,204,968), spanning 81,174 bp. Chi-square p 0.26. Describes the region, not this allele; gnomAD v4.1.1's own constrained determination. *Descriptive; no ACMG code applied.*
- SpliceAI: **below the reporting threshold**. This position is scored for a different substitution (G>T, Δ0.25 acceptor loss), so this allele was evaluated and its deltas all fell under Δ0.2 — a prediction of no splicing effect for this allele, not a gap in our data. *No ACMG code assigned.*
- Population frequency (gnomAD v4.1): grpmax **0.00667%** (amr) · FAF95 0.00226% · FAF99 0.00135% · 4/59,968 in the highest group · 9/1,610,318 alleles overall — very rare (popmax 0.00667%, amr).

| Ancestry group | Allele frequency | 1 in |
| --- | --- | --- |
| Admixed American (grpmax) | 0.00667% | 14,992 |
| African / African-American | 0.00134% | 74,796 |
| European (non-Finnish) | 0.00034% | 294,224 |

*Computational predictors are not independent (ClinGen Variant Classification guidance): AlphaMissense (Cheng et al. 2023) carries the ACMG weight for missense and conservation (phyloP/GERP/phastCons) for non-missense; REVEL (Pejaver-2022 calibrated strength bands) and SaProt (Su et al. 2023, structure-aware, ClinVar-independent protein language model, raw LLR) are shown as orthogonal agreement signals, not additive. For frequency, the gnomAD v4.1 grpmax filtering allele frequency (FAF95) is ClinGen's designated BA1/BS1 input (gnomAD v4 guidance v3.0, June 2025); BA1/BS1 thresholds are disease-specific, not a blanket 5%. Predictions, not a clinical determination.*

## Gene constraint & dosage {#gene-context}

**NPHP1** population constraint: LOEUF 0.92, pLI 4.482e-10, missense-Z 0.65749. *Lower LOEUF and higher pLI indicate a gene that tolerates loss-of-function poorly; ClinGen dosage is the curated haploinsufficiency call.*

Curated gene–disease validity (ClinGen):

- **nephronophthisis 1** — Definitive (AR)

## Protein context {#protein}


AlphaFold model confidence (whole protein): pLDDT 76.22, 45% of residues very-high.

**2 experimental structure(s)** (PDB): [1S1N](https://www.rcsb.org/structure/1S1N), [6O1Q](https://www.rcsb.org/structure/6O1Q).

## What this gene does {#gene-function}

*Describes the biological roles of NPHP1 (the gene this variant disrupts) — not effects measured for this specific variant. A damaging variant is expected to affect these functions and pathways; the degree depends on the variant.*


### Pathways affected {#pathways}

NPHP1 participates in **1 Reactome pathway** (⚕ = disease pathway):

| Pathway (Reactome) | Evidence |
| --- | --- |
| [Anchoring of the basal body to the plasma membrane](https://reactome.org/content/detail/R-HSA-5620912) | curated |

### Molecular function & processes (GO — experimentally supported) {#go}

**Biological process:** positive regulation of bicellular tight junction assembly.

## Clinical significance {#significance}

**Uncertain significance** — review status Single submitter *(criteria provided, single submitter)*, last evaluated 2022-08-22.

**Submitter consensus:** unanimous (1/1 Uncertain significance).

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Labcorp Genetics (formerly Invitae), Labcorp | Uncertain significance | criteria provided, single submitter | clinical testing | 2022-08-22 |

## Associated conditions {#conditions}

[nephronophthisis](https://sugi.bio/atlas/disease/nephronophthisis/).

**Reported phenotype names (ClinVar):** Nephronophthisis, Juvenile Nephronophthisis.

## Similar variants {#similar}

Related NPHP1 variant pages (same residue, condition, or type): [NPHP1 p.Arg325His](/variant/nphp1-p-arg325his), [NPHP1 p.Arg325=](/variant/nphp1-p-arg325), [NPHP1 c.1270-1G>A](/variant/nphp1-c-1270-minus-1g-a), [NPHP1 c.1270-2A>G](/variant/nphp1-c-1270-minus-2a-g), [NPHP1 c.143+1G>C](/variant/nphp1-c-143-plus-1g-c), [NPHP1 c.144-1G>A](/variant/nphp1-c-144-minus-1g-a), [NPHP1 c.1716+1G>T](/variant/nphp1-c-1716-plus-1g-t), [NPHP1 c.329+1G>A](/variant/nphp1-c-329-plus-1g-a).

### Data sources & attribution {#sources}

ClinVar (NCBI — public domain, built 2026-10-14); gnomAD v4.1 (Broad Institute, built 2026-10-14); AlphaMissense (Cheng et al. 2023, © Google DeepMind — CC BY 4.0, built 2026-01-27); REVEL (Ioannidis et al. 2016 — ODbL, built 2026-07-13); SaProt (Su et al. 2023 — MIT, built 2026-10-14); SpliceAI (Illumina — free for non-commercial use, built 2026-10-13); CADD (Rentzsch et al. 2019, University of Washington — free for non-commercial use, built 2026-10-10); Conservation (phyloP/phastCons/GERP) (UCSC hg38 470-way mammal (Hiller Lab) + Ensembl Compara, built 2026-07-12); gnomAD Non-coding Constraint (Gnocchi) (Chen et al. 2024, Broad Institute — CC0, built 2026-10-11); gnomAD Regional Missense Constraint (Broad Institute — CC0, built 2026-10-13); Pangolin (Zeng & Li 2022 — CC BY 4.0, built 2026-10-11); Repeat regions (UCSC — RepeatMasker, TRF, segmental duplications, built 2026-10-11); ClinGen (ClinGen, built 2026-09-22); UniProt (CC BY 4.0); Reactome / GO (CC BY 4.0, built 2026-09-23); MaveDB (per-record license, built 2026-10-11); CIViC (CC0, built 2026-09-22); Orphanet (Orphanet, built 2026-06-12)

*Primary record: NCBI ClinVar (variation 1015180). Classifications reflect these databases as of the page's build date and may change. Free reference use — not medical advice; consult the primary submitters and a clinician.*